Configuration BGP in Cisco Switch

[khalilsoltani47714]

I am looking for an order at the Configuration level BGP in switch Cisco which allows you to check if the

neighbor is UP or down.

to ensure link redundancy between two link configure with bgp, i need command to check link is up or down

[Giuseppe Larosa]

Hello @khalilsoltani47714 ,

can you provide the switch model and IOS  / IOS XE or NX OS version ?

you can post

show version

what type of BGP session are you considering ?

for eBGP there is support of eBGP fall-over from long time on directly connected neighbors.

On the switch you should use a routed port and not an SVI + a L2 access port because the first will react to port failure in the correct way, the SVI can stay up if the L2 VLAN is permitted over a trunk port for example causing issues.

Edit:

for iBGP look at the following document

https://community.cisco.com/t5/networking-documents/quot-bgp-neighbor-fall-over-command-overview/ta-p/3154490

Hope to help

Giuseppe

[khalilsoltani47714]

@Giuseppe Larosa @paul driver 

I have a catalyst switch C9500 with connections to two Nexus 7004 switches with vpc between them and what feasible in a scenario at the same level Catalyst switch C9500 with two different physical interface to associate two different vlans and BGP configuration
between C9500 and both nexus 7004 vpc between them each with different paste in this scenario I don’t want to create channel port at level C9500 to vpc at level 7004

C9500 physical interfaces Te1/0/1 associates vlan 10 IP 10.10.10.1/30 to physical interface at switch level Nexus 7K1 eth3/20 associates vlan 10 IP 10.10.10.2/30

C9500 physical interfaces Te1/0/2 associates vlan 20 IP 10.10.20.1/30 to physical interface at switch level Nexus 7K1 eth3/21 associates vlan 20 IP 10.10.20.2/30

[Giuseppe Larosa]

Hello @khalilsoltani47714 ,

ok we have understood one Cat 9500 connected to two Nexus with a vPC.

>>

C9500 physical interfaces Te1/0/1 associates vlan 10 IP 10.10.10.1/30 to physical interface at switch level Nexus 7K1 eth3/20 associates vlan 10 IP 10.10.10.2/30

C9500 physical interfaces Te1/0/2 associates vlan 20 IP 10.10.20.1/30 to physical interface at switch level Nexus 7K1 eth3/21 associates vlan 20 IP 10.10.20.2/30

is Cat 9500 in the same BGP AS as the two Nexus or in a difffent one?

it is important now to clarify if you have two eBGP sessions on Te1/0/1 and Te1/&02 or two iBGP sessions as there are differences.

eBGP could provide benefits in your scenario.

Hope to help

Giuseppe

[khalilsoltani47714]

@Giuseppe Larosa 

Switch Catalyst C9500   AS is 65001

Two Nexus 7004 AS is 65003

in this scenario i do External BGP between Switch C9500 and both Nexus 7K

Each physical  interface on switch C9500 is associated with a vlan without using portchannel.
Both nexus with vpc but I used a new link level 3 for IBGP for example vlan 30 (10.10.30.0/30)
At the VPC level I excused this vlan 30 and 10.20
Does this feasible scenario ensure the redundancy of the links?

[Giuseppe Larosa · Accepted solution]

Hello @khalilsoltani47714 ,

your scenario with eBGP allows you to have both redundancy and load balancing

just add on the Cat 9500

router bgp 65001

! eBGP load balancing

maximum-paths 2

! Accept routes from both eBGP neighbors

neighbor 10.10.0.2 remote-as 65003

neighbor 10.10.20.2 remote-as 65003

! advertise some routes that are Cat9500 routing table by connected or by an IGP

network 172.16.20.0 mask 255.255.255.0

Correct that you have removed Vlan 10,20,30 from vPC on the Nexus.

Hope to help

Giuseppe

[khalilsoltani47714]

@Giuseppe Larosa 

Thanks for your feedback
Just one last question is there an option to BGP configuration when switching the link
Switch catalyst have two links to the two nexus 7K
Shutdown first link, the traffic basucle to the second links
An option to reduce decrease the switchover  time in EBGP and IBGP

[paul driver]

Hello

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@khalilsoltani47714 wrote:

I am looking for an order at the Configuration level BGP in switch Cisco which allows you to check if the

neighbor is UP or down.

to ensure link redundancy between two link configure with bgp, i need command to check link is up or down

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show ip bgp neighbors | in state