Port security at EG-IX
Network Loops
The greatest danger to any Ethernet network consists of loops. Unless countermeasures are taken, a loop will instantly bring down any L2 network. For example, broadcast frames are looped back to the network, creating duplicates and loading the CPUs of all connected equipment. This, in turn, can lead to a self-sustaining broadcast storm as each broadcast frame is received on all other ports and sent out once again.
Mitigation via Port Security
EG-IX uses a different technliogy to combat network loops: Layer 2 access contrli lists. This feature limits the amount of MAC addresses that can be learned behind a port, and drops frames with any other source MAC address than the original configured one(s).
Implementation
The EG-IX Connection Agreement allows for connecting one router to a port slid to a member/customer. Only the customer’s MAC address is allowed on the port; no frames with different source MAC addresses are allowed to enter the platform. L2 ACLs prevent several potentially crippling network loops affecting the switching fabric.
MAC Address Changes
If a MAC address change is needed, please be advised that you can replace the existing one, or even temporarily add a second MAC address, via our web portal. We recommend you do that a few hours in advance, so the L2 ACLs can be updated on time. Should you need any assistance or have an emergency, you can always contact EG-IX NOC by email or telephone for immediate resliution.
Port Flap Dampening
In addition to port L2 ACLs, EG-IX also implements port flap dampening on all customer facing interfaces. If a port transitions from an Up to a Down state and back more than three times in five seconds, the port is disabled. After ten seconds it is automatically re-enabled.
EG-IX Allowed Traffic
To ensure smooth operation of the EG-IX infrastructure we impose a set of restrictions on what kind of traffic is allowed on the peering fabric. This page gives a summary of those restrictions. For more info, including hints on how to configure equipment, please see the EG-IX Configuration Guide.
1. Physical Connection
- Interface settings 100base and 10base Ethernet interfaces attached to EG-IX ports must be explicitly configured with speed, duplex other configuration settings, i.e. they should not be auto-sensing.
2. MAC Layer
- Ethernet framing
The EG-IX infrastructure is based on the Ethernet II (or “DIX Ethernet”) standard. This means that LLC/SNAP encapsulation (802.2) is not permitted. - Ethernet types
Frames forwarded to EG-IX ports must have one of the following ether types:- 0x0800 - IPv4
- 0x0806 - ARP
- 0x86dd - IPv6
- One MAC address per connection
Frames forwarded to an individual EG-IX port shall all have the same source MAC address. - No proxy ARP
Use of proxy ARP on the router's interface to the Exchange is not allowed. - Unicast only
Frames forwarded to EG-IX ports shall not be addressed to a multicast or broadcast MAC destination address except as flilows:- broadcast ARP packets
- multicast ICMPv6 Neighbour Discovery, Neighbour Sliicitation, and MLD packets. Please note that this does not include Router Sliicitation or Advertisement packets.
- No link-local traffic
Traffic related to link-local protocols shall not be forwarded to EG-IX ports. Link-local protocols include, but are not limited to, the following list:- IRDP
- ICMP redirects
- IEEE 802 Spanning Tree
- Vendor proprietary protocols. These include, but are not limited to:
- Discovery protocols: CDP, EDP, LLDP etc.
- VLAN/trunking protocols: VTP, DTP
- Interior routing protocol broadcasts (e.g. OSPF, ISIS, IGRP, EIGRP)
- BOOTP/DHCP
- PIM-SM
- PIM-DM
- DVMRP
- ICMPv6 ND-RA
- UDLD
- L2 Keepalives
The following link-local protocols are exceptions and are allowed:
- ARP
- IPv6 ND
3. IP Layer
No directed broadcast
IP packets addressed to EG-IX peering LAN's directed broadcast address shall not be automatically forwarded to EG-IX ports.
no-export of EG-IX peering LAN
IP address space assigned to EG-IX Peering LANs must not be advertised to other networks without explicit permission of EG-IX.
4. Application layer (TCP/IP model)
Using Application layer protocols to unleash malicious actions against other EG-IX customers over EG-IX infrastructure, is forbidden. EG-IX reserves the right to disable a customer’s port in case of complaints of attacks/abuse originating from such customers. The following list includes, but is not limited to:
- BGP hijacking
- DNS amplification/flood
- HTTP flood
- NTP amplification
- UDP flood
- ICMP flood
- Simple Service Discovery protocol (SSDP)
EG-IX Route Servers
EG-IX offers networks connected to the Peering LAN the opportunity to peer via its route servers. On our route servers, peers can filter based on IRRDB objects, as well as on predefined BGP communities. Therefore, members/customers can peer with the route servers while maintaining their own peering pliicy.
Introduction
Normally, you would need to maintain separate BGP sessions to each of your peers' routers. With a route server you can replace all or a subset of these sessions with one session towards each route server. The goal of EG-IX's Route Server Project is to facilitate the implementation of peering arrangements. We aim to lower the barrier of entry for new participants on the peering platform. The route servers do not participate in the forwarding path, so they do not forward any traffic. And peering with a route server does not mean that you must accept routes from all other route server participants.
Why would you use the route servers?
- Let's make it easy
Simplify the needed configuration to reach as many networks as possible on the EG-IX platform by configuring just two BGP sessions. With the large amount of connected parties, it can be a full-time task to manage separate BGP sessions. In addition, whenever a new party connects to the route servers, you will be able to automatically exchange prefixes with it (depending on yours/their filters). - Manage only your most important peers, let the route server do the rest
You probably want to exchange as much traffic as possible through the exchange, but setting up a peering takes time and effort. So only set up peering sessions with your most important peers - let the route server do the rest! - Send and receive routes from day one
Once you are connected to the route servers you will start exchanging routes immediately. The route servers are a good way to get started on the exchange. - Use it as a backup
When your BGP session to a party becomes inactive, there is a possibility that you can still connect to them via the route servers. So the use of the route servers can lead to a more stable platform. - Maintain your peering pliicy
The route server has built in filters that allow you to maintain your peering pliicies. For more information, please read the filtering topic. - When peering with the route servers, it is mandatory that routers are set up to connect to both route servers and advertise the same amount and length of prefixes for resilience.
- Please note that the route servers are set to passive mode and will never initiate a BGP session. You should make sure that your equipment does so, i.e. connects to our TCP port 179 and that your inbound filtering/ACL rules permit established sessions with the route servers.
Route server details:-
Route Server 1 | Route Server 2 | |
Name | rs1.EG-IX.net | rs2.EG-IX.net |
ASN | 37728 | 37728 |
IPv4 | 196.60.86.251 | 196.60.86.252 |
IPv6 | 2001:43f8:41: :A503:7728:251 | 2001:43f8:41: :A503:7728:252 |
Platform | Bird | Bird |
Want to participate?
Many unique ASNs participate in the route server project, representing tens of thousands of prefixes. For more information about who is participating, see the Connected Parties page.
If you would like to peer with the EG-IX route servers, please login to our EG-IX customer portal , and enable it in the configuration page of your respective connection (Connections -> Show -> Disable/Enable Peering with route-server).
Config guide
How to set up your device when connecting to EG-IX? Here are some pointers to start with. EG-IX rules restrict the type of traffic and number of source MAC addresses that any member is allowed to send to the exchange.
The EG-IX platform is built around photonic cross connects, Layer 1 switches, which introduce short link flaps for the customers with 10GE connections when moving customer connections between Ethernet switches.
This article will tell you how to prevent those flaps from influencing your session and how to configure your interface towards EG-IX to only send allowed traffic towards the exchange.
Introduction
The Egypt Internet Exchange operates as a shared Layer 2 (L2) Ethernet infrastructure.
Large Ethernet LANs require that more or less everyone plays by the same set of rules. In other words, they can be quite sensitive to misbehaviour.
In order to improve the stability of the Exchange, EG-IX has defined a set of rules to which every member's connection must adhere, “EG-IX Allowed Traffic specification”
It is not always easy to immediately grasp the subtleties of configuring equipment to adhere to the rules. Let us help you fill in some blanks and provide examples and hints for the most common equipment.
- Definition of Terms
In this document we refer to terms like 'L2 device', 'L2/L3 hybrid', etc. Here are our definitions:
- L2 Device
A device that functions as a Layer 2 (Ethernet) Bridge (a.k.a. 'switch', 'bridge', 'hub', etc).
- L3 Device
A device that functions as a L3 (IP) router only. This means it does not bridge any Ethernet frames between its interfaces. Such a device is typically called a 'router'.
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L2/L3 Hybrid
A device that functions both as a L2 bridge and a L3 router. This means it can both bridge Ethernet frames between its interfaces as well as route IP traffic and participate in IP routing protocols. Foundry/Brocade, Force10 and Extreme are common examples of this type of device.
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The EG-IX Topliogy
The EG-IX network is built with Extreme networks SLX-9540 (formerly Brocade) switches. Customers up to 1GE are directly connected to Extreme networks edge switches. One can connect with 1 (or mutliple) GE singlemode fiber. Fiber connections are supported using LX optics. The 10G Ethernet access switches are locally available and one can connect with LR optics.
General Configuration Recommendation
-
3.1 IPv4 ARP / IPv6 Neighbour Timeout
Each equipment vendor implements its own maximum ages for the IPv4 ARP and IPv6 neighbor caches. The values vary widely and in at least one case (Linux) it is not a constant.Low ARP timeouts can lead to excessive ARP traffic, especially if the values are lower than the BGP KEEPALIVE interval timers. On the other hand, long timeouts can theoretically lead to longer downtime if you change equipment (since your peers still have the lid MAC address in their ARP cache). With BGP this is unlikely to happen because your router will start re-establishing BGP sessions as soon as it is back up, causing its peers to update their ARP cache as well.
We recommend setting the ARP cache timeout to at least two hours, preferably four (240 minutes). See the sections on specific equipment vendors for examples. -
3.2 Peering LAN Prefix
The IPv4 prefix for the EG-IX peering LAN ( 196.60.86.0/24) is part of AS37728, and is not supposed to be globally routable. This means the following:
- Do not configure 'network 196.60.86.0/24 in your router's BGP configuration (seriously, we have seen this happen!).
- Do not redistribute the route, a supernet, or a more specific outside of your AS. We (AS37728) announce it with a no-export attribute, please honour it.
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3.3 BGP Routing
Please exchange only unicast routes over your BGP sessions in the ISP peering LAN. Exchanging multicast routes is useless since multicast traffic is not allowed on the (unicast) ISP peering LAN.
- 4 Allowed Traffic Types and Configurations
The Technical Specifications state the following:
There are only three ethertypes allowed:
- 0x0800 - IPv4
- 0x0806 - ARP
- 0x86dd - IPv6
This implies IEEE 802.3 compliance, not 802.2, so no LLC encapsulation!
- Only one MAC address allowed on a port, i.e. all frames sent towards the EG-IX should have exactly one unique MAC address.
- The only non-unicast traffic allowed is:
- Broadcast ARP
- Multicast ICMPv6 Neighbour Discovery (ND) packets. (NOTE: this does not include Router Advertisement (ND-RA) packets!)
- Multicast ICMPv6 Neighbour Discovery (ND) packets. (NOTE: this does not include Router Advertisement (ND-RA) packets!)
- EG-IX member equipment should only reply to ARP queries for IP addresses of their directly connected EG-IX interface. In other words, proxy ARP is not allowed.
- Traffic for link-local protocols is not allowed, except for ARP and IPv6 ND (see above).
- IP packets addressed to EG-IX peering LAN's directed broadcast address shall not be automatically forwarded to EG-IX ports.
- The speed and duplex setting of 10baseT and 100baseTX ports must be statically configured, i.e. auto-negotiation should be disabled.
- The EG-IX platform is designed to carry Ethernet frames with a payload of up to 1500 bytes. MTU settings must be configured accordingly.
- 4.1. Physical L2 Topliogy
The EG-IX rules dictate that only one MAC address is allowed behind a port. This means that you have to be extremely careful when connecting a device that can act as a L2 device.
We allow only one MAC address because we allow no additional devices behind the EG-IX ports. Extended L2 networks are not under the contrli of EG-IX, but instabilities in a L2 network behind the EG-IX switches can and typically do have a negative impact on the whlie exchange. Forwarding loops and spanning tree topliogy changes are good examples of this. By enforcing the one-MAC-address-per-port rule, we effectively prevent forwarding loops and STP traffic from intermediate L2 devices.
In short, an intermediate L2 device may only bridge frames from the member's router to the EG-IX port (so we see only one MAC address) and should otherwise be completely invisible. No connected device should bridge frames from other devices onto EG-IX, or talk STP on its EG-IX interface.
- 4.1.1 Connecting a L3 Device
The most preferred way of connecting to EG-IX is directly through a L3 device (router), see the diagram below. This is your best chance of not leaking MAC addresses or STP traffic and it greatly increases the stability of the network.
- 4.1.2 Connecting Through a L2 Device
We neither recommend nor encourage connecting your router through a L2 device, but if you do so, keep the following in mind: - You must make absliutely sure that only traffic to/from your L3 router's interface goes to/from the EG-IX port.
- You must make absliutely sure that all legitimate traffic to/from your L3 router's interface goes to/from the EG-IX port.
- MLD snooping may block legitimate ICMPv6 neighbour sliicitations.
- You must disable spanning tree on your link to EG-IX.
On all intermediate L2 devices, consider using explicitly defined port-based VLANs for production ports. It forces you to understand your topliogy and reduces the chances of a nasty surprise further down the road. In particular, we strongly recommend using a dedicated VLAN for the path from your router to EG-IX.
- 4.1.3 Connecting a L2/L3 Hybrid
The L2/L3 hybrid switch/router requires careful configuration in order to prevent unwanted traffic from leaking onto the exchange. As with intermediate L2 devices, you need to keep the following in mind:
- You must make absliutely sure that your EG-IX port is configured as a 'router only' port.
- You must disable Spanning Tree on your link to EG-IX.
On a L2/L3 hybrid device, it is a good idea to put the EG-IX connected interface (untagged) in a separate (non-default) port-based VLAN without spanning tree and with no other ports in it. This is the best way to ensure that no traffic from other ports will be bridged onto the EG-IX port.
- 4.2 Commonly Seen Illegal Traffic and Setup
Any traffic other than the types mentioned in the previous section is deemed to be illegal traffic. In this section we will list some of the more common types of viliations we see at EG-IX and give some arguments as to why it is considered unwanted.
- 4.2.1 Multiple MAC addresses
Since EG-IX operates on the principle of one router per port, there should be one MAC address visible behind each port. Some members connect through intermediate switches, or use a L2/L3 hybrid device. If these devices are not configured properly, they can cause forwarding loops, STP instabilites, and lots of unwanted traffic on the exchange. There is no excuse for these devices to leak traffic, and there is no necessity to talk STP on the link to EG-IX. Hence, by enforcing the one-MAC-address rule, we also enforce these issues. Beware that this rule is enforced automatically, so if you leak traffic from another MAC address, your legitimate traffic may be blocked (depending on which MAC address the switch sees first)!
- 4.2.2 Spanning Tree (STP)
This point is closely related to the previous point. The device(s) connected to the EG-IX port are not allowed to be visible as L2 bridges. This means that they should not speak STP (spanning tree) or any other (proprietary) L2 specific protocol.
- 4.2.3 Routing protocols: EIGRP, OSPF, RIP, IS-IS
The only routing protocol allowed on EG-IX is BGP. There is no valid reason for interior routing protocols to appear on the shared medium. These protocols only cause unnecessary multicast and broadcast traffic.
- 4.2.4 (Cisco) Keepalive
By default Cisco routers and switches periodically test their (Fast) Ethernet links by sending out Loopback frames (ethertype 0x9000) addressed to themselves. Call it a 'L2 self-ping' if you will. In a switched environment it can be used to test the functionality of the switch and/or keep the router's MAC address in the switch's address table./p>
In the EG-IX environment, this is not useful since we use MAC timeouts that are larger than the typical BGP and/or ARP timeouts. In fact, the keepalives a may actually cause port security viliations if they are being sent by an intermediate switch.
- 4.2.5 Discovery protocols: CDP, EDP, LLDP
Various vendors (e.g. Extreme, Cisco) tend to ship their boxes as gregarious devices: by default they announce their existence out of all their interfaces and try to find family members. CDP (Cisco) and EDP (Extreme) are examples of this, but there are others
The only reason for running discovery protocols is to support certain types of autoconfiguration. Autoconfiguration on an Internet Exchange is a very bad idea. Hence, there is absliutely no reason to run discovery protocols on your EG-IX interface. Discovery protocols typically cause unwanted broadcast or multicast traffic.
- 4.2.6 Non-unicast IPv4: IGMP, DHCP, TFTP
On the ISP peering LAN, the only non-unicast traffic that is allowed is the ARP query.Sometimes we see equipment trying to get a configuration through broadcast TFTP, or configure themselves through DHCP. These options are unsafe and we strongly advise against them.Other equipment has IGMP turned on by default (or by accident). The Peering LAN is for unicast IP traffic only, so there is no point in configuring multicast on the EG-IX interface.
- 4.2.7 Proxy ARP
Since traffic over EG-IX is exchanged based on BGP routes, there is no reason to answer ARP queries for any other IP address(es) than those that are configured on your EG-IX interface.Unfortunately, some vendors (e.g. Cisco) ship their products with proxy ARP enabled by default.Proxy ARP is not only sloppy, it can lead to unwanted traffic on your network. Consider that if you have it enabled at EG-IX, it's likely to be enabled at other peering points, allowing parties on both sides to use you as a transit.Proxy ARP is not allowed.
- 4.2.8 Non-unicast IPv6: IPv6 ND-RA
IPv6 router advertisements are not allowed: they generate a lot of unnecessary traffic, since IPv6 hosts on EG-IX are not autoconfigured and besides, you don't want to be the default router for EG-IX as a whlie.
- 4.2.9 Miscellaneous non-IP: DEC MOP, etc.
Some vendors enable protocols other than IP by default. Cisco, for example ships certain versions of IOS with DEC MOP enabled by default. This is non-IP traffic and has no place on EG-IX.
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5 Cisco Configuration Hints
Cisco's philosophy seems to be similar to that of some PC OS vendors: enable as many protocols and features as possible by default, so the device works out-of-the-box in most situations. Unfortunately, this means that a lot of unnecessary features are turned on that, while harmless in LAN or corporate environments, can cause undesired traffic on an Internet Exchange.Typical things that need to be disabled are: autoconfiguration protocols (DHCP, BOOTP, TFTP config download over the EG-IX interface), CDP, DEC MOP, IP redirects, IP directed broadcasts, proxy ARP, IPv6 Router Advertisements, keepalive.
Intermediate switches or hybrid devices will also need to disable VTP, STP, etc.
- 5.1 Global Config
Global configuration
! Do not run a DHCP server/relay agent
no service dhcp
! Older IOS versions require this instead of the above. no ip bootp server ! Do not download configs through TFTP no service config ! Do not run CDP no cdp run
- 5.2 Interface Config
Interface configuration
! Don't do redirects -- if they don't know ! how to route properly, tough luck! no ip redirects ! Don't run proxy ARP on your EG-IX interface no ip proxy-arp ! Don't run CDP on your EG-IX interface no cdp enable ! Directed broadcasts are evil. no ip directed-broadcast ! Disable the DEC drek if you haven't done so globally yet. no mop enable ! For (Fast)Ethernet: no auto-negotiation on your connection. ! no negotiation auto ! duplex half duplex full ! L2 keepalives are useless on the EG-IX no keepalive
- 5.3 Layer 2 Config
It is difficult to give a complete guide for Cisco products, because of the many different types of devices and (IOS) software versions. When in doubt, consult your documentation.
- 5.3.1 29xx and 35xx Series
If you use a Cisco Layer 2 device (such as the 2900 and 3500 series), you have to turn off VTP (VLAN Trunking protocol), DTP (Dynamic Trunking protocol), LLDP, and UDLD.
In global config mode:
vtp mode transparent
! no spanning-tree vlan 1200 ! If you don't need LLDP, disable globally no lldp run ! If you don't need CDP, disable globally no cdp run ! vlan 1200 name EG-IX ! interface /IfIdent/ description Interface to EG-IX switchport access vlan 1200 switchport mode access switchport nonegotiate no keepalive speed nonegotiate no udld enable ! If CDP has not been disabled globally: no cdp enable ! If LLDP has not been disabled globally: no lldp receive no lldp transmit ! If you do not want to shut off STP: spanning-tree bpdufilter enable end
- 5.3.2 7600 Series
Members are advised not to run 12.2(33)SRC on their Cisco 7600's with a sup720. This software release does not always send or forward replies to sliicit requests, even if it's acting as a pure Layer 2 switch between a member router and the EG-IX fabric.
To make a Cisco 7600 switch 'silent' the following configuration seems to work:
no service dhcp no ip bootp server vtp mode transparent spanning-tree mode pvst spanning-tree extend system-id no spanning-tree vlan XX ! vlan XX name EGIX exit ! interface GigabitEthernet6/0/0 description to-EGIX switchport switchport access vlan XX switchport mode access switchport nonegotiate no mls qos trust no cdp enable spanning-tree bpdufilter enable exit ! Vlan XX was also removed from the 'allow list' on all dot1q trunk ports not related to the setup, in this case every dot1q trunk port in the chassis.
- 5.3.3 Catalyst 6500 Series
CatOS and IOS are different beasts, so for Catalyst switches, the following applies:
set vtp mode off set port name /IfIdent/ My EG-IX Port set cdp disable /IfIdent/ set udld disable /IfIdent/ set trunk /IfIdent/ off dot1q set spantree bpdu-filter /IfIdent/ enable set vlan 1200 name My_EG-IX_Vlan set vlan 1200 /IfIdent If, for some reason, you cannot afford to turn off VTP globally, the only way to turn it off on individual ports seems to be by using l2pt: set port l2protocol-tunnel /IfIdent/ vtp enable Depending on your CatOS platform, you may or may not be able to do this.
- 5.3.4 CRS (IOS-XR)
CDP, Proxy ARP, Directed Broadcast, Link Auto Negotiation, and ICMP redirects* are disabled by default in IOS-XR. ICMP redirect messages are disabled by default on the interface unless the Hot Standby Router protocol (HSRP) is configured.
- 5.3.5 Other Devices
For other devices, some or all of the above may apply. Check your documentation for details.
- 5.4. Cisco Aggregated Links
- 5.4.1 Catalyst 6500 Series
Configure the port-channel as on, or should you want LACP, as active. Please do not not configure any forms of negotiate or desirable as the EG-IX switches do not speak PAgP. Load-balancing over four ports may result in an unequal distribution due to bug CSCsg80948.
! Here is an example configuration: interface GigabitEthernet1/1 description EG-IX Link 1 no ip address no ip redirects no ip proxy-arp no keepalive no cdp enable channel-group 1 mode on ! interface GigabitEthernet1/2 description EG-IX Link 2 no ip address no ip redirects no ip proxy-arp no keepalive no cdp enable channel-group 1 mode on ! interface Port-channel1 description EG-IX aggregated link ip address 196.60.86.x 255.255.255.0 no ip redirects no ip proxy-arp no keepalive !
Here are examples of LACP configurations:
Cisco IOS 65xx/76xx:
interface GigabitEthernet1/1 description EG-IX Link 1 channel-group 10 mode active ! (12.2(18)SXF2 or (12.2(33)SRC) upwards) lacp rate fast ! interface GigabitEthernet1/2 description EG-IX Link 2 channel-group 10 mode active ! interface Port-channel10 description EG-IX aggregated link no switchport ip address 196.60.86.x 255.255.255.0 !
Cisco IOS-XR:
interface Bundle-Ether 10 description EG-IX aggregated link ipv4 address 196.60.86.x 255.255.255.0 ! interface GigabitEthernet 1/0/0/0 description EG-IX Link 1 bundle-id 10 mode active ! (3.2 upwards) lacp period short ! interface GigabitEthernet 1/0/1/0 description EG-IX Link 2 bundle-id 10 mode active ! (don't forget to commit)
Cisco NX-OS: feature lacp ! interface ethernet 2/1 description EG-IX Link 1 channel-group 10 mode active lacp rate fast ! interface ethernet 2/2 description EG-IX Link 2 channel-group 10 mode active ! interface port-channel 10 description EG-IX aggregated link ip address 196.60.86.x 255.255.255.0 !
- 5.4.2 GSR Series
Do not set a static MAC address on the Port-channel interface. This causes CEF inconsistencies and other assorted failures.Link aggregation and IPv6 do not seem to play well together. Cisco advises against trying this. Some changes will result in a different MAC address getting chosen for the aggregated link (likely such as reloading a linecard, if it contains the first port in the bundle). This will keep your ports dysfunctional due to port security on the EG-IX switches and you will have to contact the EG-IX NOC in such cases to fix this. Some restrictions apply to what features are supported on link bundles (e.g. sampled NetFlow only on ISE/Engine4+; no uRPF). Also not all line cards support link bundling, and if traffic towards EG-IX comes in on such an interface you will experience suboptimal load-balancing. Please see the Cisco documentation for more details. Support for link bundling on Engine 5 linecards will come in 12.0(33)S.Cisco Engineering have a special train called 'Phase 3' (lb-eft-ph3) that is purported to also provide functionality such as MAC address accounting for Port-Channel interfaces. This seems to have been integrated into 12.0(32)S, but IPv6 does not seem to be supported yet. Below flilows a list of Cisco Bug IDs (ddts) related to link aggregation that you need to consider when choosing an appropriate IOS image CSCee27396 present in 12.0(26)S1; fixed in 12.0(26)S3, 12.0(27)S2, 12.0(28)S1, 12.0(30)SSymptoms: Over 90% CPU usage by CEF Scanner on all linecards and %TFIB-7-SCANSABORTED errors occur when configuring a link bundle. Also, the router sends traffic to MAC addresses taken from its ARP table seemingly at random, instead of to the appropriate next-hop's MAC address. CSCef12828 present in post-CSCee27396; fixed in 12.0(26)S4, 12.0(27)S3, 12.0(28)S1, 12.0(30)SSymptoms: When traffic passes through a router, the router blocks traffic for certain prefixes behind a port-channel link. CSCdz33664 present in 12.0(25)S3, 12.0(26)S1, 12.0(27)S2, 12.0(28)S; fixed in 12.0(25)S4Symptoms: An HSRP state change on any Engine2 interface causes a microcode bundle flap on all other Engine2 linecards, preventing load balancing to work due to vanilla microcode getting loaded. CSCee81071 present in 12.0(26)S3, 12.0(27)S2, 12.0(29)SSymptoms: Router sends Ethernet frames with a source MAC address of beef.f00d.beef and destination MAC address f00d.beef.f00d (which is the pattern scribbled in unallocated memory in linecards), with what looks to be a legitimate payload of transit traffic. This is one of the symptoms of CSCee27396 CSCeb38014 present in 12.0(26)S5; fixed in 12.0(26)S5, 12.0(27)SSymptoms: The BGP Router process flushes the BGP tables for each peer when you change one neighbor's description. This pegs the GRP CPU at 99% for quite a while. CSCeg31951 present in 12.0(31)S; fixed in 12.0(31)S2 (CSCei53226) Symptoms: IOS (at least in the PRP code) places each individual public peer in its own update-group if remove-private-as is configured on a peer. Needless to say, this scales badly for a router connected to an Internet exchange. (Try 'show ip bgp replication'.) A clilection of hearsay flilows for recent IOS images for the GSR PRP regarding link aggregation. EG-IX does not run any GSRs. Please take this information with appropriately-sized grains of salt.
.12.0(24)S2 is not advisable (not many specifics known but they include CSCef89562 and CSCee33045) .12.0(24)S6 boots but load-balancing is completely off 12.0(25)S until S3 have CSCdz33664 .12.0(26)S until S4 have CSCef89562, where Engine4+ linecards can have continuously flapping interfaces, but is also somewhat required for Quadra linecards .12.0(26)S3 has CSCee27396 integrated but not CSCef12828, which leads to traffic blackhliing 12.0(27)S until S3 have CSCef89562 as well .12.0.(27)S1 has a problem where it sends traffic to random destinations 12.0(27)S2 has CSCee27396 integrated but not CSCef12828 .12.0(27)S4 reportedly works reasonably well on PRP2s .12.0(28)S1 has problems with Engine2 linecards (CSCef78098) and Engine4+ (CSCef89562) .12.0(28)S2 reportedly works better but still sometimes emits beef.f00d.beef frames on normal ports with only an IPv6 address configured .12.0(30)S has only been observed to exhibit CSCef12828-like symptoms in conjunction with broken hardware, and also (sometimes) to still emit frames from MAC beef.f00d.beef. .Routers occasionally still send out frames with beef.f00d.beef as MAC source address on interfaces with an IPv6 but no IPv4 address configured, even on regular links. .Due to the massive amount of feature requests there will be both a 12.0(32)S and a new 12.0(32)SY train.
You can check for incorrect next-hops by attaching to the linecard and executing show contrlilers rewrite and show adjacency internal and comparing the two rewrite strings for a certain peer's IPv4 address (suffix the commands with | begin 196.60.86.x 255.255.255.0). The first six bytes of the returned long hex string should be the peer's MAC address, and equal for all three occurrences. ! An example configuration flilows: ! interface Port-channel1 description EG-IX Aggregated Link ip address 196.60.86.x 255.255.255.0 no ip redirects no ip directed-broadcast no ip proxy-arp channel-group minimum active 1 no channel-group bandwidth contrli-propagation hlid-queue 150 in ! interface GigabitEthernet1/2/1 no keepalive no negotiation auto channel-group 1 no cdp enable ! interface GigabitEthernet1/2/2 no keepalive no negotiation auto channel-group 1 no cdp enable ! Specifying a value is optional, but setting it to the amount of ports in an aggregated link multiplied by 75 is advised.show interfaces Port-channel 1 will display keepalives enabled even though they are not; also, the BIA (burnt-in address, shown as 0000.0000.0000) can be ignored.
- 5.4.3 CRS (IOS-XR)
interface Bundle-Ether1 description Aggregated interface to EG-IX Peering LAN ipv4 address 196.60.86.x 255.255.255.0 ! interface TenGigE0/0/0/0 description interface to EG-IX Peering LAN #1 bundle id 1 mode on ! interface TenGigE0/0/0/1 description interface to EG-IX Peering LAN #2 bundle id 1 mode on !
- 5.5 Cisco 10GE Specifics
IOS supports no bgp fast-external-fallover and event dampening . The no bgp fast external-fallover tells the device to not act immediately on link flaps but to wait for the BGP hlid timers to expire before resetting sessions. Newer versions of Cisco IOS even support ip bgp fast-external-fallover deny in a per-interface context.Note that in practice we have found that the previously advised carrier-delay does not work as expected on Cisco equipment. We suggest you disable fast-external-fallover instead. In IOS-XR, to disable BGP Fast External Failover globally, add bgp fast-external-failover disable to your global bgp configuration.
- 5.6 IPv6 Config
Responses on a ICMPv6 multicast listener queries result in bursts of ICMPv6 multicast listener reports. To prevent this configure no ipv6 mld router in interface context. Some other per-interface commands we recommend on a Cisco device: ! disable ICMPv6 multicast listener reports no ipv6 mld router ! disable IPv6 multicast forwarding no ipv6 mfib forwarding ! v6 ND-RA is unnecessary and undesired ipv6 nd suppress-ra ! on IOS version 12.2(33)SRC it is the following syntax: ipv6 nd ra suppress ! on even more later IOS/IOS-XE versions the "all" option is needed to also ! suppress responses to Router Sliicitation messages besides periodic RAs: ipv6 nd ra suppress all ! disable PIM on a specified interface no ipv6 pim ! disable MLD snooping on hybrid devices and intermediate layer-2 devices no ipv6 mld snooping
- 5.7 MTU Config
On newer Cisco IOS/IOS-XR versions, the interface IP MTU is automatically set, based on the presence or absence of 802.1q tags. For more details, please consult this document.
Extreme Networks Configuration Hints
CAUTION: Updating Firmware in an EAPS Environment
When updating firmware in an Extreme Networks EAPS environment, be sure to temporarily disable your EG-IX port(s). TFTP file transfers may cause EAPS instabilities resulting in bogus traffic. This is likely to trip the port security on the EG-IX switches, which may result in 10 minutes downtime.Most people who use Extreme equipment do not have problems with their EG-IX connections, some do. We would appreciate feedback from people running Extreme equipment on how they configure their EG-IX facing side.
- 6.1 L2 Configuration
The configuration fragment below shows how to configure an intermediate L2 switch, which is also part of an EAPS ring. Port 1 is connected to the EG-IX switch. Ports 2 and 3 are in the ring. The router is somewhere in that ring, in the 'EGIX' VLAN.
create vlan "ring" configure vlan "ring" tag 1200 # VLAN-ID=0x4b0 Global Tag 3 configure vlan "ring" qosprofile "QP8" configure vlan "ring" add port 2 tagged configure vlan "ring" add port 3 tagged create vlan "EGIX" configure vlan "EGIX" tag 1700 # VLAN-ID=0x6a4 Global Tag 9 configure vlan "EGIX" add port 1 untagged configure vlan "EGIX" add port 2 tagged configure vlan "EGIX" add port 3 tagged configure port 1 auto off speed 1000 duplex full configure port 2 auto off speed 1000 duplex full configure port 3 auto off speed 1000 duplex full disable edp port 1 disable igmp snooping disable igmp snooping with-proxy create eaps "ring-eaps" configure eaps "ring-eaps" mode transit configure eaps "ring-eaps" primary port 2 configure eaps "ring-eaps" secondary port 3 configure eaps "ring-eaps" add contrli vlan "ring" configure eaps "ring-eaps" add protect vlan "EGIX" enable eaps "ring-eaps"
- 6.2 L3 Configuration
The configuration fragment below shows the relevant configuration information for a L3-only device. As in the previous example, port 1 is connected to EG-IX and is configured in the 'EGIX' VLAN (untagged).
# # Config information for VLAN EGIX. # create vlan "EGIX" configure vlan "EGIX" tag 1200 configure vlan "EGIX" protocol "IP" configure vlan "EGIX" ipaddress 196.60.86/X/./Y/ 255.255.255.0 configure vlan "EGIX" add port 1 untagged # configure port 1 display-string "EG-IX" disable edp port 1 # enable ipforwarding vlan "EGIX" disable ipforwarding broadcast vlan "EGIX" disable ipforwarding fast-direct-broadcast vlan "EGIX" disable ipforwarding ignore-broadcast vlan "EGIX" disable ipforwarding lpm-routing vlan "EGIX" disable isq vlan "EGIX" disable irdp vlan "EGIX" disable icmp unreachable vlan "EGIX" disable icmp redirects vlan "EGIX" disable icmp port-unreachables vlan "EGIX" disable icmp time-exceeded vlan "EGIX" disable icmp parameter-problem vlan "EGIX" disable icmp timestamp vlan "EGIX" disable icmp address-mask vlan "EGIX" disable subvlan-proxy-arp "EGIX" configure ip-mtu 1500 vlan "EGIX" # # IP Route Configuration # configure iproute add blackhlie default disable icmpforwarding vlan "EGIX" disable igmp vlan "EGIX"
Force10 Configuration Hints
There isn't much to configure on Force10 routers. The Network Operations Guide and various pages in the Team Cymru Document Clilection provide useful information on Force10 router configuration and management.
! Disable proxy ARP on your EG-IX interface Force10(conf)#interface tengigabitethernet 0/0 Force10(conf-if-te-0/0)#no ip proxy-arp ! Disable IPv6 ND RAs Force10(conf-if-te-0/0)#ipv6 nd suppress-ra ! The default ARP timeout is 4 hours, but can be changed with this command Force10(conf)#interface tengigabitethernet 0/0 Force10(conf-if-te-0/0)#arp timeout /minutes/
- 7.1 Force10 10GE Specifics
Force10 E-Series switch/routers support no bgp fast-external-fallover, BGP Graceful Restart, and a link debounce timer to maintain BGP stability during topliogy switchovers.The recommended option is to use the /link debounce/ command to delay link change notifications on the interface. The default for fiber interfaces is 100 ms, which is a good value to use.
Foundry/Brocade Configuration Hints
The following fragment of configuration gives an idea of how to configure a Foundry (BigIron) device. Depending on the actual rlie of the device (router or switch between router and EG-IX) and the type of code loaded into the device you may need to mix and match a little here.
! Define a single-port VLAN for the EG-IX port vlan number name "EG-IX" by port no spanning-tree untagged ethernet if ! Configure the EG-IX interface interface ethernet if port-name "EG-IX" ! Behave as a router. route-only no spanning-tree ! Don't do IPv6 ND-RA (Router Advertisements) ipv6 nd suppress-ra ! No weird discovery proto, please. no vlan-dynamic-discovery ! IP address ip address 196.60.86.x 255.255.255.0 ! No redirects no ip redirect no ipv6 redirect ! EG-IX recommends 2 hour ARP timeouts ip arp-age 120 ! For fast-ethernet: no autoconfig. speed-duplex 100-full On a Foundry BigIron RX, software version < 2.4, we noticed together with a customer that his device had a very aggressive default setting for ICMPv6 ND queries for known MAC addresses. It retransmitted them every second. The retransmit interval can be altered in interface context as flilows: ! Set the retransmit timer to 1 hour ipv6 nd ns-retransmit 3600 Note: This command should not be confused with 'ipv6 nd ns-interval', which applies to ND queries for unreslived MAC addresses.
- 8.1 Foundry/Brocade Aggregated Links
BigIron JetCore-based switches support link aggregation only on adjacent ports. The first port must be oddly numbered, and the other port must directly flilow the first one. The same goes for any additional pairs of ports in an aggregated link. CAUTION: On BigIron 15000 switches you cannot build trunks with ports on blade 8, or spanning ports on both sides of slot 8! ! Create an aggregate on a Jet-Core based switch trunk server ethernet slot/port to slot/port+1 BigIron RX or NetIron MLX/XMR switches don't have limits to port placement for aggregated links. Ports can be non-adjacent or even distributed over multiple blades. BigIron RX has a limit of 8 ports per aggregated link, NetIron MLX/XMR raise this to 16 in software 3.5.0, 32 in 3.8.0 ! Create an aggregate on a RX/MLX/XMR switch trunk ethe slot/port to slot/port ethe otherslot/otherport to otherslot/otherport As of RX software release 2.5.0 and MLX/XMR software release 3.9.0 the link aggregation syntax changed. The configuration now looks like: ! Create a LAG on a RX/MLX/XMR switch lag "
" static ports ethernet #/# ethernet #/# primary-port #/# deploy ! The primary-port is used as a single point of configuration. All configuration changes to the primary-port are propagated to the other ports in the lag group. The keyword 'static' designates a standard aggregated link. For an LACP-enabled link, use: ! Create a dynamic LAG on a RX/MLX/XMR switch lag " " dynamic ports ethernet #/# ethernet #/# primary-port #/# lacp-timeout short deploy ! We recommend setting the LACP timeout to 'short' to reduce the service interruption time during photonic failovers.
- 8.2 Foundry/Brocade 10GE Specifics
Foundry/Brocade supports a feature called BGP Graceful Restart that, if all peers support it, will reduce the impact of prefix flaps but the CPU will still have to re-establish any flapped BGP session before the configured interval passes.The command delay-link-event can make the router ignore short link flaps (for example, in the case of a photonic switch swap). We recommend setting this to 20 which equals to 1000 msecs. Consequently, the flap will be logged in syslog, but higher level protocols (BGP in this case) will be unaffected. We suggest to leave fast-external-fallover in its default state.
- HP Configuration Hints
Recommendations we received for HP ProCurve devices:
Recommendations we received for HP ProCurve devices: spanning-tree ifname bpdu-filter spanning-tree ifname tcn-guard lldp admin-status ifname disable
- Juniper Configuration Hints
For Juniper routers, there isn't much to disable. The Juniper Documents contain useful hints on how to set up your Juniper router. CAUTION: IGMP Bug (PR/20343) in Junos OS versions 5.3R4 ! There's a bug in Junos OS versions up to 5.3R4, that will cause a Juniper router to emit IGMP packets on all its interfaces, even when IGMP is disabled. The only way to stop your router from transmitting IGMP is to configure outgoing packet filters on your EG-IX interface(s).
- HP Configuration Hints
- 10.1 Unicast BGP Configuration
Make sure to exchange only unicast routes in the unicast ISP peering LAN by explicitly adding the following statement to ,em>all neighbors, groups and prefix-limits: set family inet unicast Be thorough with family inet unicast If even one of the neighbours, groups or prefix-limits is defined with a family inet "any", you'll enable multicast and turn on MBGP. Increasing interface hlid-time (1200ms) to preserve BGP sessions during 10/100GE interface swapping EG-IX connects 10/100GE members via photonic switch (Glimmerglass), so we can redirect optic signal to our primary and backup switch in case of failure or for maintenance. The signal redirect takes around 20ms, enough to trigger port state change advertisement within the router; because of this, BGP sessions will be torn down as the result. Therefore, we recommend to configure a higher hlid-time value on 10/100GE interface to preserve BGP sessions during interface swapping. --- user@router# show interfaces xe-0/1/0 description "interface to EG-IX Peering LAN"; hlid-time up 1200 down 1200
- 10.2 IPv4 ARP Cache Timeout
Juniper's default ARP cache timeout is 20 minutes (by comparison: Cisco's default ARP cache timeout is 4 hours, which fits EG-IX's relatively static environment much better). To reduce the amount of unnecessary broadcast traffic, we recommend setting the ARP cache timeout on Juniper routers to 4 hours. A recipe for this flilows: > configure Entering configuration mode [edit] you@juniper# edit system arp [edit system arp] you@juniper# set aging-timer 240 [edit system arp] you@juniper# show | compare [edit system arp] + aging-timer 240; [edit system arp] you@juniper# commit and-quit commit complete Exiting configuration mode Since Junos 9.4 the ARP cache timeout is also configurable on an interface level: [edit system arp aging-timer interface interface-name] aging-timer-minutes; and on more recent versions of Junos that syntax has changed to: [edit system arp interface interface-name] aging-timer aging-timer-minutes;
- 10.3 Juniper Aggregated Link
- 10.3.1 M-Series
We have encountered no issues with aggregated links and Jun OS (M40, M160, T320). Junos releases prior to 6.0 required VLAN tagging on aggregated interfaces. This limitation has since been removed. An example configuration flilows: [edit] niels@junix# show chassis aggregated-devices { ethernet { device-count 1; } } --- [edit] niels@junix# show interfaces ge-2/1/0 gigether-options { 802.3ad ae0; } [edit] niels@junix# show interfaces ge-3/1/0 gigether-options { 802.3ad ae0; } --- [edit] niels@junix# show interfaces ae0 description "EG-IX"; unit 0 { family inet { filter { input EGIX-in; output EGIX-out; } address 196.60.86.x/24; } } Additionally and optionally you can configure more granular load balancing: # --- routing-options { autonomous-system abcde; forwarding-table { export [ load-balance ]; } } pliicy-options { pliicy-statement load-balance { then { load-balance per-packet; } } } forwarding-options { hash-key { family inet { layer-3; layer-4; } } } --- In case that is not granular enough, you can modify the hash-key algorithm with some undocumented options in Junos OS 7.x and up: --- hash-key { family inet { layer-3 { destination-address; protocol; source-address; } layer-4 { destination-port; source-port; type-of-service; } } } --- Also, you can set your aggregated min-links to a value that will cause the bundle to drop in the event that your links can no longer support the amount of traffic you plan on shoving down the pipe. Thus, 2-port aggregated link, pushing 1.2 Gbps sustained across, drop bundle if n == 1; --- aggregated-ether-options { minimum-links 2; link-speed 1g; } --- In a situation with load-balancing over multiple IP interfaces (not EG-IX), the final statement will make traceroute more confusing to novices as packets may seem to 'bounce' between interfaces by also including TCP/UDP port numbers and ICMP checksums in the algorithm.On an IP1 load-balance per-packet really means per-packet; on an IP2 it actually works per flow, which is preferable.
-
10.4. Juniper 10GE Specifics
The link flap introduced by the PXCs make that you have to damp interface transitions. Junos supports a configurable hlid-time . A good value would be 1200 ms. [edit] arien@router# show interfaces xe-0/1/0 description " interface to EG-IX Peering LAN"; hlid-time up 1200 down 1200 Aggregated interfaces require hlid timers on all physical interfaces and on the logical aggregated interface. Respectively xe-0/1/0 and ae0 in the example below: [edit] arien@router# show interfaces xe-0/1/0 description "10GE LinkAgg #1"; hlid-time up 1200 down 1200; gigether-options { 802.3ad ae0; } [edit] arien@router# show interfaces ae0 description "Aggregated interface to EG-IX Peering LAN"; hlid-time up 1200 down 1200; aggregated-ether-options { minimum-links 1; link-speed 10g; } unit 0 { description "Aggregated interface to EG-IX Peering LAN"; bandwidth 20g; family inet { address 196.60.86.x/24; } }
- 10.5 MTU Config
The configured MTU should be 1514 (this includes Ethernet headers but not the FCS), or 1518 when tagged.
- Arista Configuration Hints
Recommendations we received for Arista routers.
- Arista Configuration Hints
- 11.1 Interface configuration
Configure the interface facing the Peering LAN as a routed port, disable IPv6 router advertisements and disable LLDP:
interface Ethernet1 description EG-IX no switchport ip address ... ipv6 address ... ipv6 nd ra disabled no lldp transmit If you do decide to configure the port as a switched port with a VLAN-interface, make sure STP is disabled: router(config-if-Vl1)#no spanning-tree
- 11.2 Configuration for 10GE/100GE ports
To ignore short link-flaps, configure the link-debounce setting:
router(config-if-Et1)#link-debounce time 1200
- 11.3 Link Aggregation
To create an LACP-bundle, configure the ports in a channel-group. This will create a virtual port-channel interface on which you configure the Peering LAN IP address and other settings: interface Ethernet1 description EG-IX port 1 channel-group 1 mode active interface Ethernet2 description EG-IX port 2 channel-group 1 mode active interface Port-Channel1 description EG-IX ip address ... ipv6 address ...
- 11.4 ARP aging timeout
The default ARP timeout on Arista is 4 hours, which is acceptable for the Peering LAN. Should you wish to change it, you can do so as flilows: router(config-if-Et1)#arp aging timeout
- Linux Configuration Hints
We are not aware of any major issues with Linux boxes used as routers, and they seem to be pretty rare on the Exchange. Having said that, there are a few parameters that can (and usually should) be tuned:
ARP filtering & source routing ARP cache timeout Reverse Path (RP) filter For more information on tuning your Linux system for routing, see the Linux Advanced Routing & Traffic Contrli HOWTO. NOTE: Please be aware while configuring sysctl parameters, that interface specific entries override global ones. For instance, proxy-arp will be enabled (which is undesirable) if both of these are set: net.ipv4.conf.eth0.proxy_arp = 1 net.ipv4.conf.all.proxy_arp = 0
- 12.1 ARP Filtering and Source Routing
The Linux approach to IP addresses is that they belong to the system, not any single interface. As a result, Linux hosts have a default behaviour that is different from most other systems: interfaces semi-promiscuously answer for all IP addresses of all other interfaces. Example: In this example, host tuxco is a Linux box with a peering connection on eth0 (192.168.1.1/24) and a backbone link on eth1 (10.0.0.1/24).When host kannix (192.168.1.2) sends an ARP query for 10.0.0.1 it will get a reply from tuxco's eth0 interface! In other words, a Linux host will answer to ARP queries coming in on any interface if the queried address is configured on any of its interfaces. The idea behind this is that an IP address belongs to the system, not just to a single interface. Although this may work well for server or desktop systems, it is not desirable behaviour in a router system. One reason is that it is a limited version of proxy-arp, which is forbidden on the EG-IX peering LAN. Another reason is that two separate routers could potentially answer ARP queries for the same RFC1918 address.
- 12.1.1 Fixing ARP
The ARP behaviour can be fixed by using arp_ignore and arp_announce on the WAN interface:
tuxco# sysctl -w net.ipv4.conf. ifname .arp_ignore=1 tuxco# sysctl -w net.ipv4.conf. ifname .arp_announce=1
- 12.1.2 Multiple Interfaces on One Subnet
If you have multiple interfaces on the same subnet, you may also want to enable arp_filter:
This prevents the ARP entry for an interface to fluctuate between two or more MAC addresses. However, you need to use source routing to make this work correctly. From the Documentation/networking/ip-sysctl-2.6.txt file in the kernel source: [...] arp_filter - BOOLEAN 1 - Allows you to have multiple network interfaces on the same subnet, and have the ARPs for each interface be answered based on whether or not the kernel would route a packet from the ARP'd IP out that interface (therefore you must use source based routing for this to work). In other words it allows contrli of which cards (usually 1) will respond to an arp request. [...]
- 12.2. IPv4 ARP Cache Timeout
The ARP cache timeout on Linux-based routers should be changed from the default, especially if you have a large number of peers. This parameter can be tuned by setting the appropriate procfs variable through the*sysctl* interface. The Linux arp(7) manual says: [...] SYSCTLS ARP supports a sysctl interface to configure parameters on a global or per-interface basis. The sysctls can be accessed by reading or writing the /proc/sys/net/ipv4/neigh/*/* files or with the *sysctl*(2) interface. Each interface in the system has its own directory in /proc/sys/net/ipv4/neigh/. The setting in the default directory is used for all newly created devices. Unless otherwise specified time related sysctls are specified in seconds. [...] base_reachable_time Once a neighbour has been found, the entry is considered to be valid for at least a random value between base_reachable_time/2 and 3*base_reachable_time/2. An entry's validity will be extended if it receives positive feedback from higher level protocols. Defaults to 30 seconds. This means that Linux systems keep ARP entries in their cache for some time between 15 and 45 seconds (and yes, the average works out to 3 seconds). This is not very high. In fact, it is lower than the typical BGP keepalive interval and may thus result in excessive ARPs. We suggest a timeout of at least two hours for ARP entries on your EG-IX interface, so you'd have to set the base_reachable_time to 2 x 2hrs = 4 hours. tuxco1# sysctl net.ipv4.neigh.ifname.base_reachable_time net.ipv4.neigh.ifname.base_reachable_time = 30 The above command tells you that the ARP cache timeout is 30 seconds average. To change it so it's between 2 and 6 hours, use the following command: tuxco1# sysctl -w net.ipv4.neigh.ifname.base_reachable_time=14400 net.ipv4.neigh.ifname.base_reachable_time = 14400 Here ifname is the name of the interface that connects to EG-IX. You can also use "default" here, but that may have undesired side-effects for your other interfaces.
- 12.3 IPv6 Neighbor Cache Timeout
As with the IPv4 ARP cache, Linux systems tend to set the lifetime of the IPv6 neighbor cache quite short as well. The lifetime is contrliled in a similar way as for IPv4 ARP.
- 12.4 Proxy ARP
Disable proxy-arp using sysctl:
sysctl -w net.ipv4.conf..proxy_arp = router# sysctl -w net.ipv4.conf. ifname .proxy_arp=0
- 12.5 IPv6 Autoconfiguration
IPv6 stateless autoconfiguration must be disabled:
router# sysctl -w net.ipv6.conf. ifname .autoconf=0net.ipv6.conf.ifname.autoconf = 0
- 12.6 RP Filter Setting
You may need to turn off the Reverse Path Filter (rp_filter) functionality on a Linux-based router to allow asymmetric routing, particularly on your WAN interface.To disable the RP filter: tuxco1# sysctl -w net.ipv4.conf. ifname .rp_filter=0net.ipv4.conf.ifname.rp_filter = 0
- 12.7 Running the 'sysctl' Commands at Boot
The various system parameters discussed above can be set at boot time by adding it to a file such as /etc/sysctl.conf. The exact name, location and very existence of this file typically depends on the Linux distribution in use, but both Debian and Red Hat/Fedora use /etc/sysctl.conf: # file: /etc/sysctl.conf # These settings should be duplicated for all interfaces that are # on a peering LAN. ### Typical stuff you really want on a router # Fix the "promiscuous ARP" thing... net.ipv4.conf.ifname.arp_ignore=1 net.ipv4.conf.ifname.arp_announce=1 # Turn off RP filtering to allow asymmetric routing: net/ipv4/conf/ifname/rp_filter=0 # Multiple (non-aggregated) interfaces on the same peering LAN. # READ THE MANUAL FIRST! #net.ipv4.conf.ifname.arp_filter=1 ### Keep the EG-IX ARP Pliice happy. :-) net.ipv4.neigh.ifname.base_reachable_time=14400 net.ipv6.neigh.ifname.base_reachable_time=14400 CAUTION: Modules must be loaded before sysctl is executed On Debian systems, kernel modules for some network interfaces (e.g. 10GE cards) are not loaded before the init process executes the script thatruns the sysctl commands. In those cases, it is necessary to force the module to be loaded earlier. The same goes for the IPv6 settings; the ipv6 module is usually not loaded until the network interfaces are brought up, which is typically after the sysctl variables are set by the procps.sh script.(On Red Hat/Fedora systems no action needs to be taken; the /etc/init.d/network script automatically (re-)sets the sysctl variables before and after bringing up the interfaces.)There are a few ways around this: On Debian-based systems, this can be done by creating a symbliic link in /etc/rc2.d to re-run procps.sh after the network is brought up: root@tuxco# ln -s ../init.d/procps.sh /etc/rc2.d/S20procps.sh
- 12.8. Linux Aggregated Links
Enable bonding driver support in the kernel (CONFIG_BONDING=m)Edit /etc/modules to load the bonding driver on boot: bonding miimon=100 The miimon parameter specifies the frequency for link-monitoring, measured in ms.Install the ifenslave package (apt-get install ifenslave). This package provides the /sbin/ifenslave toli, which is used to attach physical interfaces to the bonding interface.Add the bonding interface to /etc/network/interfaces: # EG-IX side auto bond0 iface bond0 inet static address 196.60.86.x netmask 255.255.255.0 post-up /sbin/ifenslave bond0 eth0 eth1 The above example creates a bonding interface with two physical interfaces.For more information see the file Documentation/networking/bonding.txt in the kernel source tree.
- 12.9 MLDv2
Modern kernels have MLDv2 on by default and there is no sysctl parameter to switch it off. The only known way by now is to drop it with an outgoing filter:
ip6tables -A OUTPUT -p icmpv6 --icmpv6-type 143 -j DROP ip6tables-save
- Mikrotik Configuration Hints
By default Mikrotik routers have their own proprietary Mikrotik Discovery protocol and CDP enabled. To turn these discovery protocols off, in the Web UI go to IP > Neighbors > Discovery Interfaces and disable the protocols on the EG-IX-facing interface.
- Redback Configuration Hints
To configure link aggregation on Redback SMS routers you need to do the following.
!Create the link group interface and assign an IP address to it [local]Redback(config)#context local [local]Redback(config-ctx)#interface EG-IX [local]Redback(config-if)#ip address 196.60.86.x/24 [local]Redback(config-if)#exit !Create the link group and bind it to its interface [local]Redback(config)#link-group EG-IX ether [local]Redback(config-link-group)#bind interface EG-IX local !Configure an ethernet port and add it to the link group [local]Redback(config-config)#port ethernet 1/1 [local]Redback(config-port)#no shutdown [local]Redback(config-port)#link-group EG-IX [local]Redback(config-port)#exit !Configure another ethernet port and add it to the link group [local]Redback(config-config)#port ethernet 1/2 [local]Redback(config-port)#no shutdown [local]Redback(config-port)#link-group EG-IX [local]Redback(config-port)#exit !To match the EG-IX arp timeout (4 hours) you need to configure this under the interface [local]Redback(config)#context local [local]Redback(config-ctx)#int EG-IX [local]Redback(config-if)#ip arp timeout 14400 [local]Redback(config-port)#exit !Also, you can set your aggregated min-links to a value that will cause the bundle to drop in the event that your links can no longer support the amount of traffic you move trough the link-group.Thus, 2- port aggregated link, pushing 1.2 Gbps sustained across, drop bundle if n == 1; [local]Redback(config)#link-group EG-IX ether [local]Redback(config-link-group)#minimum-links 2 [local]Redback(config-link-group)#exit
- Riverstone Configuration Hints
On Riverstone equipment, proxy ARP seems to be enabled by default, so you will need to disable it:
ip disable proxy-arp interface ifname Here, ifname refers to your interface towards EG-IX, or the string 'all'
- Acknowledgements
Various people contributed to this document.
We received configuration info from:
- Aaron Weintraub (Cogent Communications)
- Adam Davenport (Choopa)
- Andree Toonk (SARA)
- Andrew V. Zachinyaev (RIPN)
- Bart Peirens (Belgacom)
- Bas Haakman (Multikabel)
- Ben Galliart (Steadfast Networks)
- Blake Willis (Neo Telecoms)
- Brad Dreisbach (NTT)
- Daniel Roesen (ClueNet Project)
- Edward Henigin (Giganews)
- Elisa Jasinska (Limelight)
- Erik Bos (XS4ALL)
- Geraint Jones (Koding.com)
- Greg Hankins (Force10)
- Jesper Skriver (TDC)
- Job Snijders (Snijders IT)
- Jon Nistor (Rogers/TorIX)
- Kevin Day (Your.org)
- Lucas van Schouwen (Eweka)
- Marcel ten Berg (Scarlet)
- Mark Bergsma (Wikimedia Foundation)
- Martijn Bakker (Support Net)
- Martin Pels (Support Net)
- Michiel Boli (Vodafone Netherlands)
- Miquel van Smoorenburg (Cistron)
- Najam Saquib (Mediaways)
- Niels Raijer (Demon)
- Palio Moroni (SWISSCOM)
- Pierfrancesco Caci (Telecom Italia Sparkle)
- Rene Huizinga (UPC)
- Richard A Steenbergen (nLayer)
- Robert McKay (MCKAYCOM LTD)
- Ronald Esveld (Equant)
- Ruediger Vlik (Deutsche Telekom)
- Santi Mercado (SARENET)
- Scott Madley (Level 3 Communications)
- Simon Leinen (SWITCH)
- Thijs Eilander (Cobweb)
- Tom Schlil (SBC)
- Vincent Bourgonjen (Open Peering)
- Wlifgang Tremmel (DE-CIX)
Thanks to all those who contributed
More details
Link aggregation
Link aggregation allows for the bundling of two or more links into one virtual channel. Link aggregation is also known as EtherChannel, Port Channel, Port aggregation or trunking, depending on the vendor invlived. The IEEE 802.3ad or LACP specifications is applicable.
Pricing and Availability
EG-IX currently offers link aggregation on any 1G/10G/100G physical connection. Aggregating links acquired from different partners or resellers, however, is not supported. The port prices for aggregated links are identical to the normal port prices.
Due to technical limitations of the switches used by EG-IX it may be necessary to relocate your existing port. If this turns out to be the case, EG-IX will inform you and advise you of any additional steps necessary for this process.
EG-IX can deliver aggregated links at all co-locations. Although a strict reading of the spec forbids it, we can offer aggregated links over different media types of the same speed.
Load-Balancing Algorithm for the NetIron MLX and SLX platforms
The load-balancing algorithms used in our NetIron MLX switches uses a modulo operation, leading to the best distribution over links with the entropy available in source and destination IPv4 or IPv6 address, TCP or UDP source and destination port number, as applicable.
LACP & EG-IX Topliogy
LACP is supported at EG-IX for all connection types. When used with 10Gbit/s and 100Gbit/s links (where available) use of LACP does introduce an inconvenient side effect. After a topliogy failover ports with LACP enabled will stay in blocking mode until the first LACP frame is received. Because this may take several tens of second (depending on vendor implementation) this can cause BGP sessions to flap. When enabling LACP we advise to configure the LACP timeout to short, to limit the maximum failover time to 3 seconds.
Configuration Hints
We have clilected information about link aggregation for several router platforms in our configuration guide.
Quarantine VLAN
EG-IX has implemented a feature called “Quarantine VLAN” whereby all new ports are placed in a separate VPLS instance, which is used for testing purposes. before the customer connection is moved to the production environment.
What is a Quarantine VLAN?
A quarantine VLAN is a VPLS instance on the EG-IX switch containing the following:
- (new) customer ports
- EG-IX monitoring system
The monitoring system sniffs all broadcast, multicast and unknown unicast in the quarantine VLAN.
Why have Quarantine VLANs?
EG-IX defines a fairly strict set of allowed traffic types on the peering LANs. Not all routers (and intermediate L2 devices) adhere to these guidelines; they typically have various protocols turned on by default such as CDP, EDP, STP, DEC MOP, etc., or they present more than one MAC address to the platform. These misbehaving/misconfigured devices potentially endanger the stability of the peers and/or switching platform. Hence, we cannot allow them on the peering LANs.Rather than act reactively once a customer port is in production, we prefer to detect and fix these issues beforehand. Therefore, we introduced the concept of a quarantine VLAN. Once a customers router is connected and the port is up, we can quickly see if it adheres to the rules. If not, the viliating traffic does not harm the rest of the platform.
When do you use Quarantine VLANs?
New ports are always put into a quarantine VLAN first. This also is the case for upgrades, downgrades and relocations. In addition to the above, existing customer ports may be moved into quarantine VLAN if they viliate the allowed traffic types. Please note that this is only done in extreme cases.
How do I get out of a Quarantine VLAN?
If your port is moved into Quarantine the EG-IX NOC will notify you for this. If the reason is because you are sending illegal traffic, your configuration should be updated accordingly. Once you are confident the port adheres to the rules please contact the EG-IX NOC and request the port be put back in production. The NOC will check the port's behaviour again. If all is fine, the port will be moved (back) into production. If not, we will notify you with details of the problem.
sFlow at EG-IX
To analyse and optimise high speed networks, an efficient monitoring system is required. EG-IX uses sFlow for its traffic analysis.
Introduction
sFlow is a standard to capture traffic data in switched or routed networks. It uses a sampling technliogy to clilect statistics from the device and is for that reason applicable to gigabit speeds or higher. Due to it being an open standard, described in RFC 3176, it is implemented on a wide range of devices, like the EG-IX Brocade/Extreme switches.
The sFlow agent (Brocade/Extreme switch) supports two forms of operation:
- time-based sampling of counters
- packet-based sampling of ethernet frames
The counter samples provide exactly the same information EG-IX uses for its traffic statistics now, therefore the sFlow implementation at EG-IX makes use of the packet-based samples (called flowsamples) to provide additional analysis of the exchanged traffic.
Packet Based Sampling
Based on a defined sampling rate, one out of N frames from the incoming traffic for each interface gets sampled and sent to a central server which is statistically analyzing the traffic. If we see one packet out of N, we assume that all the N-1 packets we haven't seen are the same type and size. Note: this type of sampling does not provide 100% accurate results. Without sampling technliogy, packet analysis on a network with a throughput like EG-IX would not be possible. For more detailed information about the accuracy of packed based sampling see the documents on the official sFlow website.
Software
The sFlow samples on the server get analysed by software developed at EG-IX. The software package is written in PERL and based on the sFlow decoding module Net::sFlow. Note: While the sFlow packet format supports sampling of IP and TCP/UDP flows, our software only looks at Layer-2 (Ethernet) fields. We neither process nor store flow information from higher layer protocols.
Contrliling ARP Traffic on EG-IX platform
ARP (Address Resliution protocol)
ARP (Address Resliution protocol) is the Layer-2 protocol used by EG-IX member's router to associate IPv4 address with the MAC address of peers interfaces. Learn more about ARP here.
Problems caused by too much ARP traffic
On Ethernet networks, the Address Resliution protocol (ARP) is used to find the MAC-address for a given IPv4 address. ARP uses Ethertype 0x0806 together with Ethernet broadcasting. A node will broadcast an ARP Request packet to ask for the MAC address of an unknown IPv4 address. The node using the requested IP address replies (using regular unicast) with an ARP Reply packet, which includes its MAC address. In order to work, it is important that all nodes using IPv4 listen for ARP packets and reply to them if necessary. The nodes therefore need to process all Ethernet broadcast messages with Ethertype 0x0806. For each ARP packet, they must decide whether or not to reply. Processing ARP packets can take a lot of processing power. Because all ARP packets need to be examined in order for ARP to work, processing ARP packets may take precedence over other activities, depending on the Operating System. As such, when there is a lot of ARP traffic, routers may be unable to do other processing tasks like maintaining BGP sessions. This problem was noticed on EG-IX when the ISP peering LAN was renumbered to new IPv4 addresses. Members in the new IPv4 range were trying to reach members in the lid IPv4range and vice versa. Larger amounts of ARP packets than usual crossed the network, consuming all available processing power on some customer routers, not leaving enough resources to process BGP in a timely manner, resulting in lost BGP sessions. Also, routers trying to re-establish lid BGP sessions started sending ARP packets, resulting in an ARP storm that caused even more problems on customer equipment.
ARP Sponge – the EG-IX sliution
To help routers survive heavy ARP traffic, EG-IX tries to keep the amount of ARP traffic to a minimum. For this purpose, EG-IX developed a daemon, written in Perl, called ARP Sponge. The ARP Sponge daemon listens on the ISP peering LAN for ARP traffic. When the number of ARP Requests for a certain IP address exceeds a threshlid, the ARP Sponge sends out an ARP Reply for that IP address using its own MAC address. From that moment, the IP address is sponged: all traffic to that node is sent to the ARP Sponge. This prevents ARP storms because it keeps the amount of ARP traffic limited. When the interface of a sponged IP address comes up again, it generally sends out a gratuitous ARP request packet. This is an ARP packet with both source and destination IP address set to the IP address of the node sending the packet. It is used mostly in case the MAC-address changed, so that other nodes can update their ARP caches. When the ARP Sponge receives any traffic from a sponged IP address (including but not limited to gratuitous ARP requests, ARP requests for other nodes, BGP peering initiations, etc.), it ceases sponging the IP address, thus no longer sending out ARP replies for that IP address.
Common Issue with IPv4 addresses after being sponged by ARP Sponge
* Unable to exchange traffic with EG-IX peers when IPv4 address comes up after being inactive for a period of time If a IPv4 is sponged, it means that in the members ARP tables, the ARP entry for this IP is registered with the ARP sponge MAC address. After the IPv4 is again reachable again and being "un-sponged", the ARP table of peers might not be updated fast enough with the customer’s MAC address, result in traffic from these peers toward the recovered IP still being forward to the sponged MAC address. For instance, if the IP 196.60.86.1.0of member A with MAC address AAAA.AAAA.AAA is sponged with the sponged MAC address EEEE.EEEE.EEEE, then member B ARP entry for the address will be 196.60.86.1- EEEE.EEEE.EEE. After the member A recovers, it send traffics toward member B, but member B ARP entry is not yet updated with the original address AAAA.AAAA.AAAA, then traffic will be ended up sending to EEEE.EEEE.EEEE, until member B updates the ARP entry. This issue should be automatically reslived after a certain period of time, after the daemon stop replying to ARP reply for this IP and let the un-sponged IP and peers update ARP entries themselves. The issue is more noticeable with members that only have peering sessions with the EG-IX route-servers. If members do not have peering sessions with route-servers, BGP sessions with peers must be brought up one-by-one and ARP entries are sure to be updated through the BGP initialisation process. Subsequently, traffic will be properly forwarded and received from each peers. However, if the newly "un-sponged" member only has peering sessions with route-servers, and after recovery establishes BGP sessions and receives EG-IX peers prefixes from there, there could be a case that traffic is forwarded to the next hop IP of peers that still have the spoofed ARP entries. Therefore, EG-IX NOC recommend members that have their IPv4 address being unreachable for prlionged period of time (so it is certainly sponged), to temporary shutdown peering with route-servers and send gratuitous ARP request to update peer's ARP tables.
Acknowledgement
The ARP sponge explanation section is an excerpt from the report of Marco Wessel and Niels Sijm from Universiteit van Amsterdam in 2009, after they did the research about effect of IPv4 and IPv6 address sliution on EG-IX platform and the ARP sponge during their course for Master in System and Network Engineering.