Eigrp routes.

Unanswered Question
Nov 17th, 2008

Hi,

I am reciving 1 Eigrp 10.1.1.0/22 route from 2 upstrem routes, as External Eigrp (redistributed by BGP into Eigrp).Now I like to preffer one route over other for my out bound traffic, How shell I achive this?.

I am thinking to change delay metric of Eigrp on upstream routers when redistributing from BGP to Eigrp and lower delay metric will win .


Any sugesstion?


Regards,

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Jon Marshall Mon, 11/17/2008 - 03:16

Mohammed


So at the moment they are both seen as equal cost. If so then yes you should modify the delay but be aware that delay is calculated on the egress interface that points upstream so you may want to do it on the router receiving the routes or if there are any intermediate routers on those -


http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0080094cb7.shtml#eigrpmetrics


Jon

mohammedrafiq Mon, 11/17/2008 - 03:31

Thanks Jon,

We only can do this on upstream (WAN) routersat HQ, the route recive is on our core 6500 sw at HQ, which redistribute into all LAN switch through EIGRP.so if we do on 6500 it will effect all the other routes,we only want to influence one route 10.1.1.0/22 which is our remote site and connected through two diffrent srevice provider.

Additonaly, we only can do on one WAN A router, cos its only recieving 10.1.1.0/22 route and other WAN B is recieving lot more, so we do not want to change there,the delay on WAN Bis 100, so we can do it on WAN A as 50.

Regards,

Jon Marshall Mon, 11/17/2008 - 03:36

Mohammed


You may also want to consider using an offset-list with an acl to just modify the route you are interested in.


Jon

csco10716389 Mon, 11/17/2008 - 03:38

U may take help of policy map for that particular route and exit interface.

mohammedrafiq Mon, 11/17/2008 - 03:43

Thanks,

Where can do this route minpulation on WAN router or Core 6500 ?


Regards,

csco10716389 Mon, 11/17/2008 - 04:00

U have to do on the WAN router running Eigrp process or if the BGP network is under your jurisdiction then u can manipulated the Incomming traffic using MED or ASprepend.

csco10716389 Mon, 11/17/2008 - 03:42


I mistaken,

U may take help of Route map for that particular route and exit interface.

Mohamed Sobair Mon, 11/17/2008 - 04:50

Mohammed,


Jon has provided a useful link to help, I would just add that to keep in mind the (Delay & Bandwidth) are considered Eigrp metric values only if other K values are not included in the metric, I mean (Reliability , Load , MTU).


However, an Eigrp adjacency neighbors are not performed if the Metric weights are not the same.


changing the Delay or Bandwidth should accomplish what you are looking for after calculating both.


HTH

Mohamed

Giuseppe Larosa Mon, 11/17/2008 - 05:58

Hello Mohammed,

you can take advantage of redistribution points of BGP into EIGRP.


You can build a two blocks route-maps


first block will use prefix-list or ACL to match routes that you want to increase seed metric


route-map modify_seed_BGP_to_EIGRP permit 10

match ip address 10

set metric bandwidth2 delay2 reliability2 loading2 mtu2


route-map modify_seed_BGP_to_EIGRP permit 20

! here routes with normal seed metric


then in the EIGRP process


router eigrp 100

default-metric bandwidth1 delay1 reliability1 loading1 mtu1

no auto-summary

red bgp your.aS route-map modify_seed_BGP_to_EIGRP


note: this more complex setup is needed only if you want to be selective and you want to influence outbound path only for a subset of routes.

Otherwise as Jon suggested you can simply increase the delay on C6500_2 interface to WAN router because cost is calculated outbound direction


Hope to help

Giuseppe


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