[bdNOG] Automatic update of Next Hops in Routing Policies for Internet bound traffic in interior routers.

Thu Nov 21 18:47:31 BDT 2013

Hello everyone,

Please view this email in plain text with mono-spaced fonts because it has a text based diagram.
Please take a look at it. Generally, Policy Routing is done in Distribution Routers (DR) to send
Internet bound traffic from a specific prefix to appropriate Border Router (BR) so that upward and
downward traffic uses the same upstream SP. When prefixes are moved from one BR to another BR due to
business requirements, Network Admin needs to manually update Next Hop information in Policy Routing
configurations in all DRs. If the number of prefixes and/or the number of DRs increases, this
becomes cumbersome. Is there any way (vendor specific and/or vendor independent) to automate these
updates?

192.168.0.0/26--------\       <OSPF>
192.198.1.64/26-------(DR1)------|
192.200.2.128/25------/          |
                                  |   ---(BR1)->  <eBGP Adv. 192.168.0.0/24 to upstream A>
192.168.0.64/26-------\          |  /
192.198.1.0/26--------(DR2)-----[SW]----(BR2)->  <eBGP Adv. 192.200.2.0/24 to upstream B>
192.200.2.64/26-------/          |  \
                                  |   ---(BR3)->  <eBGP Adv. 192.198.1.0/24 to upstream C>
192.168.0.128/25------\          |
192.198.1.128/25------(DR3)------|
192.200.2.0/26--------/

(DR)=Distribution Router, (BR)=Border Router, [SW]=Switch.

With thanks and best regards,

ANIRUDDHA BARUA
Email: aniruddha.barua at colbd.com, cto at colbd.com