Re: BGP Path Preference in EIGRP PE-CE protocol

Hi,

I know that there is a long list of BGP best path selection criteria, but I
am unable to understand why R8 is selecting R3 as the best-path out of the
two

R8#sh ip bgp vpnv4 all 9.9.1.1
BGP routing table entry for 9:9:9.9.1.1/32, version 67
Paths: (2 available, best #2, table ABC)
Flag: 0x800
  Advertised to update-groups:
        1
  Local
    9.9.7.7 (metric 2) from 9.9.9.9 (9.9.9.9)
      Origin incomplete, metric 5, localpref 100, valid, internal
      Extended Community: SoO:78:78 RT:9:9 Cost:pre-bestpath:128:156160
        0x8800:32768:0 0x8801:9:130560 0x8802:65281:25600 0x8803:65281:1500
      Originator: 9.9.7.7, Cluster list: 9.9.9.9
      mpls labels in/out 22/27
  Local
    9.9.38.3 from 0.0.0.0 (9.9.8.8)
      Origin incomplete, metric 158720, localpref 100, valid, sourced, best
      Extended Community: SoO:78:78 RT:9:9 Cost:pre-bestpath:128:158720
        0x8800:32768:0 0x8801:9:133120 0x8802:65282:25600 0x8803:65281:1500
      mpls labels in/out 22/nolabel

Is it because it is locally sourcing the path while redistributing EIGRP
into BGP under the "address-family ipv4 VRF_A"?

Same is the case on R9

R9#sh ip bgp vpnv4 all 9.9.1.1/32
BGP routing table entry for 9:9:9.9.1.1/32, version 43
Paths: (2 available, best #1, no table)
Flag: 0x4800
  Advertised to update-groups:
        1 2
  Local, (Received from a RR-client)
    9.9.7.7 (metric 2) from 9.9.7.7 (9.9.7.7)
      Origin incomplete, metric 5000000, localpref 100, valid, internal,
best
      Extended Community: SoO:78:78 RT:9:9 Cost:pre-bestpath:128:156160
        0x8800:32768:0 0x8801:9:130560 0x8802:65281:25600 0x8803:65281:1500
      mpls labels in/out 26/27
  Local, (Received from a RR-client)
    9.9.8.8 (metric 3) from 9.9.8.8 (9.9.8.8)
      Origin incomplete, metric 158720, localpref 100, valid, internal
      Extended Community: SoO:78:78 RT:9:9 Cost:pre-bestpath:128:158720
        0x8800:32768:0 0x8801:9:133120 0x8802:65282:25600 0x8803:65281:1500
      mpls labels in/out 26/22

I am totally lost :-(

Please help as my exam is next week and I am going totally bonkers with this

Thanks,
Malik
On Sun, Feb 27, 2011 at 5:27 PM, Malik Nouman Ahmad <djmalik_at_gmail.com>wrote:

> Hi,
>
> I am stuck in a bit of a puzzle.
>
> ---R9(RR)---
> / \
> R8(PE) ----- R7 (PE)
> | |
> R3(CE) ----- R1 (CE)
>
> - All routers have Lo0 with format 9.9.X.X/32 where X is the router number
> - PE-CE protocol is EIGRP under VRF A
> - PEs and RR have MP-BGP configured and CEs have EIGRP configured between
> them i.e. CEs have backdoor link
>
> R8s routing table has
> D 9.9.3.3/32 via 9.9.38.3
> B 9.9.17.0/24 via 9.9.7.7
> B 9.9.1.1/24 via 9.9.7.7
>
> R7s routing table has
> D 9.9.1.1/32 via 9.9.17.1
> B 9.9.38.0/24 via 9.9.8.8
> B 9.9.3.3/24 via 9.9.8.8
>
> R3's routing table has
> D 9.9.1.1/32 via 9.9.13.1
> D 9.9.17.0/24 via 9.9.13.1
>
> R1's routing table has
> D 9.9.3.3/32 via 9.9.13.3
> D 9.9.38.0/24 via 9.9.13.3
>
> My aim is that the RR reaches 9.9.1.1/32 and 9.9.17.0/24 through
> R9->R8->R3->R1. If R8 is down, then it can go directly R9->R7->R1. R8
> prefers BGP routes for 9.9.1.1/32 over the EIGRP routes from R3 and
> therefore is not loading it into its BGP table
>
> I am unable to do it, please help me
>
> Thanks,
> Malik

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Received on Sun Feb 27 2011 - 17:52:08 ART