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Beginner

WAN router connections to leaf switches and routes "anomalies"

Hello,

we are setting up a small dc using Nexus 9000 series switches (9332PQ as spine and 2x9372TX + 2x9396PX as leaf)

below a quick design:

 

Untitled.jpg

 

 

WAN router is connected to the border leaf switches with 2 L3 point-to-point links and with 2 different BGP sessions.

Leaf01 and Leaf02 are configured with vPC and the IP fabric underlay has been configured with iBGP + IGP (OSPF) (https://www.cisco.com/c/en/us/td/docs/switches/datacenter/pf/configuration/guide/b-pf-configuration/IP-Fabric-Underlay-Options.pdf)

 

Looking at Leaf01 all seems good:

 

 

leaf01# sh ip bgp 
BGP routing table information for VRF default, address family IPv4 Unicast
BGP table version is 51, Local Router ID is 10.2.1.21
Status: s-suppressed, x-deleted, S-stale, d-dampened, h-history, *-valid, >-best
Path type: i-internal, e-external, c-confed, l-local, a-aggregate, r-redist, I-injected
Origin codes: i - IGP, e - EGP, ? - incomplete, | - multipath, & - backup

   Network            Next Hop            Metric     LocPrf     Weight Path
*>e0.0.0.0/0          10.0.51.2                                      0 ASNXYZ i

the default route is received via the correct interface/peer.

 

 

But on leaf02:

 

leaf02# sh ip bgp 
BGP routing table information for VRF default, address family IPv4 Unicast
BGP table version is 54, Local Router ID is 10.2.1.22
Status: s-suppressed, x-deleted, S-stale, d-dampened, h-history, *-valid, >-best
Path type: i-internal, e-external, c-confed, l-local, a-aggregate, r-redist, I-injected
Origin codes: i - IGP, e - EGP, ? - incomplete, | - multipath, & - backup

   Network            Next Hop            Metric     LocPrf     Weight Path
* e0.0.0.0/0          10.0.51.6                                      0 ASNXYZ i
* i                   10.2.1.21                         100          0 i
*>i                   10.2.1.21                         100          0 i

even if i've got the eBGP route, the preferred is the one received via iBGP (and route reflectors).

should not be preferred the eBGP route? 

 

 

Also moving forward and looking at leaf03 (for example):

 

leaf03# sh ip bgp 
BGP routing table information for VRF default, address family IPv4 Unicast
BGP table version is 7, Local Router ID is 10.2.1.23
Status: s-suppressed, x-deleted, S-stale, d-dampened, h-history, *-valid, >-best
Path type: i-internal, e-external, c-confed, l-local, a-aggregate, r-redist, I-injected
Origin codes: i - IGP, e - EGP, ? - incomplete, | - multipath, & - backup

   Network            Next Hop            Metric     LocPrf     Weight Path
* i0.0.0.0/0          10.2.1.21                         100          0 i
*>i                   10.2.1.21                         100          0 i

I've got the default route from only 1 next-hop (leaf01) instead of two (leaf01 and leaf02). Is that behavior correct?

Shouldn't be something like:

   Network            Next Hop            Metric     LocPrf     Weight Path
* i0.0.0.0/0          10.2.1.22                         100          0 i
*>i                   10.2.1.21                         100          0 i

Thanks, kind regards

 

 

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