Solved: Re: BGP Between Nexus and IOS Stack

benolyndav · ‎12-16-2021

Hi

Please see attached, the x2 Nexus 5k Switches are configured has a VPC pair already VPC domain 10

I want to configure ibgp between the Nexus Switches and the IOS Sack, the IOS Stack is runing EBGP peering with ISP Router,

we have subnets Southbound of Nexus which I would like to advertise to the IOS Stack using IBGP

Ive been scratching my head with this lab and cant think of the best way to do this, ??? any help appreciated..

paul driver · ‎12-17-2021

Hello

The main thing to reiterate would be that the if you were to do this then the igbp connections into the cisco stack would need to be two separate physical routed interfaces and not within a vpc as running a layer 3 over the vpc wouldn’t be an appropriate design choice due to the vpc L2 functionality.

Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

View solution in original post

Richard Burts · ‎12-17-2021

I am a bit confused about this question. If there are networks southbound of the Nexus switches I would think that some Interior routing protocol (OSPF, EIGRP, etc) would be a better choice of how to advertise them. Why would you want to use IBGP for this?

HTH

Rick

benolyndav · ‎12-17-2021

Hi

Its a requirment for a new SDN project where we have to run BGP between nexus and the Stack.

Thanks

marce1000 · ‎12-17-2021

- I am confused about that too , note that nexus is data-center oriented, in that context I would advise static knowledge-based routes to the "dmz-perimeter-isp". Preferably with a firewall in between , or stated otherwise. 'Don't terminate BGP on the nexus'

M.

-- Each morning when I wake up and look into the mirror I always say ' Why am I so brilliant ? '
When the mirror will then always repond to me with ' The only thing that exceeds your brilliance is your beauty! '

benolyndav · ‎12-17-2021

HI

The IOS Stack where we peer using EBGP with ISP is a private wan(vrf) the IBGP is just to advertise new subnets into BGP and move away from statice routing,

Thanks

paul driver · ‎12-17-2021

Hello

The main thing to reiterate would be that the if you were to do this then the igbp connections into the cisco stack would need to be two separate physical routed interfaces and not within a vpc as running a layer 3 over the vpc wouldn’t be an appropriate design choice due to the vpc L2 functionality.

Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

pman · ‎12-17-2021

Hi,

IBGP between SW1 and STACK interfaces can be L3/SVI, if SVI so this VLAN is local to SW1-STACK only
IBGP between SW2 and STACK interfaces can be L3/SVI, if SVI so this VLAN is local to SW2-STACK only
IBGP between SW1 and SW2 interfaces can be L3/SVI, if SVI so this VLAN is local to SW1-SW2 only
Regarding the question of whether to establish the IBGP between SW1 and SW2 over the peer-link or a dedicated interface - depending on Nexus type and version https://www.cisco.com/c/en/us/support/docs/ip/ip-routing/118997-technote-nexus-00.html