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Bronze

NX-OS and BGP Backdoor

Hello!

I'm trying to configure BGP Backdoor on my Nexus 5548TP switches. I have BGP peerings established, however in this case, I have a DR facility and I only want some EIGRP routes preferred over the BGP learned routes. In this case, we have a couple vendors that have VPNs to both locations. I want the primary path to always be preferred and if that disappears from routing table, use the BGP learned route. I have an eBGP session with my firewall which is advertising the routes in question, so the AD is 20, which is fine for interfaces hanging off the firewall, but the other routes i want them to have AD of 200 so my EIGRP route is preferred. I've tried using a route-map on NX-OS for this without much luck.

NX-OS v 5.2(1)N1(4)

DR-CORE1(config-route-map)# router bgp 65107

DR-CORE1(config-router)# address-family ipv4 uni

DR-CORE1(config-router-af)# network 3.3.3.3/32 ?

  <CR>

  route-map  Apply route-map to modify attributes

DR-CORE1(config-router-af)# network 3.3.3.3/32 route-map ?

  WORD                             Route-map name (Max Size 63)

  test1 (no abbrev)                Known route-map name

DR-CORE1(config-router-af)# network 3.3.3.3/32 route-map test1 ?

  <CR>

DR-CORE1(config-router-af)# network 3.3.3.3/32 route-map test1

DR-CORE1(config-router)# route-map test1

DR-CORE1(config-route-map)# set ?

  as-path             Prepend string for a BGP AS-path attribute

  comm-list           Set BGP community list (for deletion)

  community           Set BGP community attribute

  dampening           Set BGP route flap dampening parameters

  extcomm-list        Set BGP extcommunity list (for deletion)

  extcommunity        Set BGP extcommunity attribute

  forwarding-address  Set the forwarding address

  interface           Output interface

  ip                  Configure IP features

  ipv6                Configure IPv6 features

  level               Where to import route

  local-preference    BGP local preference path attribute

  metric              Set metric for destination routing protocol

  metric-type         Type of metric for destination routing protocol

  nssa-only           OSPF NSSA Areas

  origin              BGP origin code

  tag                 Tag value for destination routing protocol

  vrf                 Set the VRF for next-hop resolution

  weight              BGP weight for routing table

1 REPLY
Hall of Fame Super Silver

NX-OS and BGP Backdoor

It's tricky given that BGP's AD is always going to beat out EIGRP's all other things being equal. Most of the things you can do with BGP route-maps involve making one BGP route preferred over another.

You could inject the preferred path as a static route (AD = 1) to the firewall using an ip sla operation and having the static route track that. Once the ip sla operation fails, the static route is withdrawn and then the BGP-learned route (AD = 20) will take precedence.

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