[c-nsp] Redistributed EIGRP Route Preferred over EBGP?

[Bruce Pinsky]

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Chris Mason wrote:
> Hi,
> 
> I have a DMVPN setup running EIGRP between the HUB and SPOKES. The HUB
> is then running E-BGP back to the core.
> The HUB and SPOKES are all within the same EIGRP AS so the routes
> being learnt are internal EIGRP routes.
> 
> I have remote sites which have a primary and secondary router with
> EIGRP being used on the secondary router.
> The primary router will be advertising the same prefixes via BGP.
> 
> On the HUB, I am redistributing the EIGRP learnt routes into BGP.
> In the scenario below I am also learning the same prefix via BGP for
> the sites primary circuit.
> 
> Based on the following output I would expect the BGP learnt route to
> be preferred over the EIGRP redistributed route as I am setting a
> weight of 64000 on the BGP route.
> The EIGRP route will have a weight of 32768 because it is locally redistributed:
> 
> Router# show ip bgp vpnv4 vrf VPN-A 172.31.254.105/32
> BGP routing table entry for 65222:400:172.31.254.105/32, version 125981
> Paths: (2 available, best #2, table VPN-A)
>  Advertised to update-groups:
>        2    3    5    8
>  100 65000 65116
>    172.31.235.1 from 172.31.235.1 (172.16.0.33)
>      Origin incomplete, metric 0, localpref 100, weight 64000, valid, external
>      Extended Community: RT:65222:400
>      mpls labels in/out /nolabel
>  Local
>    172.31.238.166 from 0.0.0.0 (172.31.235.254)
>      Origin incomplete, metric 297372416, localpref 100, weight
> 32768, valid, sourced, best
>      Extended Community: RT:65222:400
>        Cost:pre-bestpath:128:297372416 (default-1850111231) 0x8800:32768:0
>        0x8801:44:12928000 0x8802:65281:284444416 0x8803:65362:1400
>      mpls labels in/out /nolabel
> 
> I can't work out why we are preferring the EIGRP path to the BGP path?
> Does anyone have any ideas or am I missing something obvious?
> 

If I understand you correctly, an internal EIGRP route is being preferred
in the RIB over an eBGP route.  That would make sense as EIGRP has an admin
distance of 20 and eBGP has an admin distance of 170.

In the output you show above, the redist'd EIGRP route is preferred in BGP
but that has no bearing on whether the eBGP route is preferred over an
EIGRP route.

Or am I missing something in your explanation?


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bep

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