BGP and EIGRP Routing Preference

Answered Question
Mar 6th, 2014
User Badges:

Under a branch scenario with both MPLS w/ BGP and Gre Tunnels with EIGRP and EIGRP within the branch LAN, how can we influence path selection to prefer the MPLS route, which redistributes all remote networks from BGP->EIGRP which then is propagated down to the branch LAN as EIGRP 170 routes. Under the current scenario, all traffic traverses the GRE tunnel which sees the same paths as EIGRP 90 Internal routes. We would prefer to not modify AD anywhere in the environment or introduce BGP onto the L3 switching. If possible we'd like to keep the current routing topology.


   Mutual Redist              Native EIGRP

-----HUB A-----         ------VPN HUB----

          ^

BGP CLOUD                  GRE Tunnel

          ^

-----MPLS------          -----EIGRP-----

     Router                         Router

     Mutual Redist               Native EIGRP

         |                                   |

         |                                   |

         --------------------------------

              LAN SWITCH EIGRP

Correct Answer by Jon Marshall about 3 years 5 months ago

If you do not want to modify the AD or run BGP then some other possible solutions -


1) if the IPs from the remote site(s) are summarisable then advertise a summary via the GRE tunnels.


2) on the LAN EIGRP router configure another EIGRP AS and then reconfigure the L3 switch to peer with this new AS. Then redistribute the routes received from the GRE tunnel into the new AS. You would probably also need to modify the metric either with a delay on the L3 switch connection to the LAN EIGRP router or using offset lists.


3) if you are simply trying to use the GRE tunnels if the BGP router fails then you could simply not run EIGRP between the L3 switch and the LAN EIGRP router and just have a floating static default route on the L3 switch pointing to the EIGRP router.


However 3) does not work if you want failover on a per remote site basis.


Just some suggestions.


Jon

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (1 ratings)
Loading.
Correct Answer
Jon Marshall Thu, 03/06/2014 - 08:31
User Badges:
  • Super Blue, 32500 points or more
  • Hall of Fame,

    Founding Member

  • Cisco Designated VIP,

    2017 LAN, WAN

If you do not want to modify the AD or run BGP then some other possible solutions -


1) if the IPs from the remote site(s) are summarisable then advertise a summary via the GRE tunnels.


2) on the LAN EIGRP router configure another EIGRP AS and then reconfigure the L3 switch to peer with this new AS. Then redistribute the routes received from the GRE tunnel into the new AS. You would probably also need to modify the metric either with a delay on the L3 switch connection to the LAN EIGRP router or using offset lists.


3) if you are simply trying to use the GRE tunnels if the BGP router fails then you could simply not run EIGRP between the L3 switch and the LAN EIGRP router and just have a floating static default route on the L3 switch pointing to the EIGRP router.


However 3) does not work if you want failover on a per remote site basis.


Just some suggestions.


Jon

cdall1979 Thu, 03/06/2014 - 09:03
User Badges:

Jon, thanks I was leaning towards summaries into the branch from the rest of the network and also summaries into the HUB sites as well, leaving the MPLS as preferred for the remote branches. Thanks!

Peter Koltl Sat, 03/08/2014 - 13:39
User Badges:
  • Silver, 250 points or more
  • Community Spotlight Award,

    Member's Choice, March 2016

You can turn all your internal EIGRP routes to external by using

redistribute connected

instead of

network A.B.C.0

command.

Actions

This Discussion