1

I have following Setup

R1 --- R2 --- R3 --- R4 --- R5

The same network is being advertised from R1 and R5. There is some difference in delay between the two paths R1-R2 and R4-R5. So the route from R1 is being viewed as the preferred path by R3 who learnes about both routes. This is the topology output of R3:

R3#show ip eigrp topology 172.16.244.0/24 | include from|Composite metric|Total delay|Originating router|tag is|Minimum bandwidth
  172.27.0.1 (GigabitEthernet0/1), from 172.27.0.1, Send flag is 0x0
      Composite metric is (3285401600/3284746240), route is Internal
        Minimum bandwidth is 1000000 Kbit
        Total delay is 50121250000 picoseconds
        Originating router is 172.16.244.2
        Internal tag is 20
  172.26.0.1 (GigabitEthernet0/0), from 172.26.0.1, Send flag is 0x0
      Composite metric is (3286056960/3285401600), route is Internal
        Minimum bandwidth is 1000000 Kbit
        Total delay is 50131250000 picoseconds
        Originating router is 172.16.244.3
        Internal tag is 20

As you can see, both the routes have a route-tag of 20. On R4, i have following route-map configuration:

R4#show running-config | section route-map
route-map VPNMAIN permit 10
 match tag 25
 set metric 1000000 10 255 1 1500
route-map VPNMAIN permit 20
R4#show running-config | s r e
router eigrp LAN
 !
 address-family ipv4 unicast autonomous-system 1
  !
  topology base
   distribute-list route-map VPNMAIN in 
   distribute-list route-map VPNMAIN out 
  exit-af-topology
  network 172.16.0.0 0.15.255.255
  eigrp default-route-tag 20
 exit-address-family

So i want to catch all routes with a route-tag of 25 and manipulate the metric to a better value. What i want to achieve is, that R3 prefers routes from R5 if they come with a route-tag 25. Im not really sure on which direction (in or out) i have to map the distribute list to achieve what i want. Back to topic. I change the route-tag on R5:

R5#configure terminal  
Enter configuration commands, one per line.  End with CNTL/Z.
R5(config)#router eigrp LAN
R5(config-router)#address-family ipv4 unicast autonomous-system 1
R5(config-router-af)#eigrp default-route-tag 25
*Sep 22 14:20:45.147: %DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 172.19.0.2 (GigabitEthernet0/0) is resync: default route tag configured
R5(config-router-af)#end

but nothing seems to change on R3. The new route-tag is visible, but the metric are still tha same.

R3#show ip eigrp topology 172.16.244.0/24 | include from|Composite metric|Total delay|Originating router|tag is|Minimum bandwidth
  172.27.0.1 (GigabitEthernet0/1), from 172.27.0.1, Send flag is 0x0
      Composite metric is (3285401600/3284746240), route is Internal
        Minimum bandwidth is 1000000 Kbit
        Total delay is 50121250000 picoseconds
        Originating router is 172.16.244.2
        Internal tag is 20
  172.26.0.1 (GigabitEthernet0/0), from 172.26.0.1, Send flag is 0x0
      Composite metric is (3286056960/3285401600), route is Internal
        Minimum bandwidth is 1000000 Kbit
        Total delay is 50131250000 picoseconds
        Originating router is 172.16.244.3
        Internal tag is 25

Something i observed. The route-map doesnt seem to match anything. Not sure if this is normal that there are no matches if used as distribute lists:

R4#show route-map 
route-map VPNMAIN, permit, sequence 10
  Match clauses:
     tag 25 
  Set clauses:
    metric 1000000 10 255 1 1500
  Policy routing matches: 0 packets, 0 bytes
route-map VPNMAIN, permit, sequence 20
  Match clauses:
  Set clauses:
  Policy routing matches: 0 packets, 0 bytes

What am I missing? How can i achieve my goal? I work with the default K-Values (Bandwith & Delay)

4
  • this is possibly not an answer, but there is cisco docs that says to use offset-list feature. refs: ciscopress.com/articles/article.asp?p=1613547&seqNum=2 and cisco.com/c/en/us/support/docs/ip/…
    – Effie
    Sep 22 at 15:51
  • I read about the offset command. But as far as i understand it, it can only be used to make a path worse and not better. Quote: "An offset-list value of 20 on R4 increases the Composite Metric for the path R2-R4 by 20 on R2"
    – Mario Jost
    Sep 22 at 18:44
  • my gut feeling says that option "make path better" should be strictly forbidden, because it will break distance vector computation. it still may allow setting a better metric for a specific link. that second link i think has an example where delay is changed. is there something preventing setting offset on R2 or on R3, or delay on R1?
    – Effie
    Sep 22 at 19:25
  • We dont control the network from R1 to R2. This is in the hands of our provider. We want to be able to switch to our own Network (FlexVPN) if needed routing wise. We control R3, so maybe the plan would be to do something there. I was planing on manipulating the routes on R4 because this is our Hub router that connects to all the branch locations. I thought it would be best to adjust the metric there so it gets announced already as "better" path to our core network (R3, that is).
    – Mario Jost
    Sep 22 at 20:17

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