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ERA-IX Peering LAN Route Servers


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Full Mesh BGP Peering

Computer networks use route reflectors. To ease peering between many routers. When a network BGP network without route reflectors will require N*(N-1)/2 BGP sessions to remain in full-mesh topology. Or even twice as many if all networks operate both IPv4 and IPv6.

A network with 3 routers will require just 3*(3-1)/2 = 3 BGP sessions, but a network with 19 routers will require 19*(19-1)/2 = 171 BGP sessions in a full-mesh topology!

As it would be incredibly difficult to maintain this amount of bilateral peering sessions, a route-reflector can be set up to distribute the routes. In the case of an internet exchange this route-reflector is commonly known as a route-server.


Route Server BGP Peering

When a route-server is utilized, all members can peer and announce their routes to the central route-server. The route-server will take care of filtering the routes and distributing the remaining, validated routes to the other members.

ERA-IX provides two route-servers for redundancy, these route-servers are hosted on two seperated physical machines to ensure continuity.

Peering in the route-server model and setting up direct (bilateral) peering sessions are not exclusive, they can be used to complement each other.

Route-Server filtering

By default, our route-servers are configured with the following filtering policy

  • Drop invalid IRR routes, routes announced to our route-servers must be properly administered in their relevant IRR.
  • (ROV) Drop Invalid, when a route does not match it's ROA, the route is dropped. Routes which do not have a ROA or match their ROA are accepted.
  • PeeringDB Never via Route Servers, routes matching ASNs set up with Never via route servers on peeringDB are dropped by the route-servers. Make sure this is disabled if you peer with route-servers.

Peering LAN Route-servers

Name ASN IPv4 Address Max-routes (IPv4) IPv6 Address Max-routes (IPv6)
Route Server 1 206221 185.1.240.1 300000 2001:7f8:12a::1 100000
Route Server 2 206221 185.1.240.254 300000 2001:7f8:12a::254 100000

Configuring Route-server Peering

To get started with our route-servers you will have to configure BGP sessions towards our route-servers. With default policy in place, the following (example) BGP configuration can be adapted to work inside your network:

ERA-IX route-server configuration example

router bgp 64512
  neighbor era-ix-ipv4 peer group
  neighbor era-ix-ipv6 peer group
  neighbor era-ix-ipv4 remote-as 206221
  neighbor era-ix-ipv6 remote-as 206221
  neighbor era-ix-ipv4 description era-ix
  neighbor era-ix-ipv6 description era-ix
  no neighbor era-ix-ipv4 enforce-first-as
  no neighbor era-ix-ipv6 enforce-first-as
  neighbor era-ix-ipv4 send-community large
  neighbor era-ix-ipv6 send-community large
  neighbor era-ix-ipv4 maximum-routes 300000
  neighbor era-ix-ipv6 maximum-routes 100000
  neighbor 185.1.240.1 peer group era-ix-ipv4
  neighbor 185.1.240.254 peer group era-ix-ipv4
  neighbor 2001:7f8:12a::1 peer group era-ix-ipv6
  neighbor 2001:7f8:12a::254 peer group era-ix-ipv6
  !
  address-family ipv4
    neighbor era-ix-ipv4 prefix-list export-prefixes out
  !
  address-family ipv6
    neighbor era-ix-ipv6 activate
    neighbor era-ix-ipv6 prefix-list export-prefixes out

The most important statements (some of which might be unique):

  • no enforce-first-as This statement disables the check on the first AS in the AS-PATH. If you do not set this, inbound updates will be ignored and you will see zero prefixes from our route-servers.
  • send-community large This statement enables sending communities to our route-servers, allowing you to use them for traffic-engineering.

We recommend applying explicit and strict import and export route filtering, in the example import filtering has been left out. Route-maps and prefix-lists can be used to achieve the desired effect.

Enforcing Policy

Peering with route-servers does not have to mean you lose all control of your peering policy!
With route-servers you remain in control about who your routes are exported to. To learn more, visit our BGP Communities documentation.