Page 376 of Internet Routing by Halabi

From: Angelo De Guzman (ghie_pogi@xxxxxxxxx)
Date: Tue Aug 27 2002 - 09:22:36 GMT-3


   
Hi to All,

  R10 ------R7
    | /
    | /
    | /
    R5

R10 and R7 in AS 1.
R5 in AS 3

   My objective is for R10 to prefer the path to R7
going into AS 5. I'm only allowed to change the metric
to make this work. The link between R5 and R10 will
only be used when R5 to R7 link fails.

Here's my Config.

R5

router BGP 3
   network 172.16.220.0 mask 255.255.255.0
   neighbor 172.16.20.1 remote-as 1
   neighbor 172.16.20.1 route-map setmetric out
   neighbor 192.68.6.2 remote-as 1
   neighbor 192.68.6.2 route-map setmetric1 out
   no auto-summary

route-map setmetric permit 10
  set metric 100

route-map setmetric1 permit 10
  set metric 50

These are the sh ip bgp for R7 and R10

R10#sh ip bgp
BGP table version is 3, local router ID is 192.68.11.1
Status codes: s suppressed, d damped, h history, *
valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network Next Hop Metric LocPrf Weight
Path
*> 172.16.220.0/24 172.16.20.2 100 0 3 i
* i 192.68.6.1 50 100 0 3 i
*> 192.68.11.0 0.0.0.0 0 32768 i

R7#sh ip bgp
BGP table version is 7, local router ID is 192.68.9.2
Status codes: s suppressed, d damped, h history, *
valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network Next Hop Metric LocPrf
Weight Path
* i172.16.220.0/24 172.16.20.2 100 100 0 3
i
*> 192.68.9.1 50 0 3
i
*>i192.68.11.0 192.68.6.2 0 100 0 i

Why does R10 still prefers the link between R10 and
R5. Eventhough the network 172.16.220.0/24 has a
metric of 100.
Thanks,
Angelo



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