I have a lab where I'm connecting a Cisco CSR1000V and a Nexus 9000 switch. These devices are connected back to back. Relevant configuration is:


interface Port-channel1
mtu 9216
interface Port-channel1.1000
encapsulation dot1Q 1000
 ip address
vrrp 1 ip
vrrp 1 priority 150
vrrp 1 track 1 decrement 70
interface GigabitEthernet2
mtu 9216
no ip address
speed 1000
channel-group 1

Nexus 9K:

interface Vlan1000
ip address
interface port-channel1
switchport mode trunk
mtu 2916
spanning-tree port type normal
ip route
interface Ethernet1/1
switchport mode trunk
mtu 2916
channel-group 1

Connection is between router G2 and Nexus E1/1. Problem is, they can't talk to each other. The Router is master in vrrp status. Interfaces look good:


Port Channel 1:

Router Port channel 1

The Nexus switch shows the same interface status:


Nexus E1/1

Port Channel 1:

Nexus po1

So, all looks up but can't ping switch from router:

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to, timeout is 2 seconds:
Success rate is 0 percent (0/5)

At this point I can't tell if the issue is on the CSR or in the Nexus switch. Any help would be appreciated.


  • 1
    Please, never use images for text. Simply copy the text and paste it into the question using the Preformatted-text option ({}). Also, you cannot connect a layer-3 port channel to a layer-2 port channel, and VRRP is pointless with a single router.
    – Ron Maupin
    Jul 1, 2020 at 23:05
  • 1
    Have you created VLAN 1000 on the Nexus? Type show spanning-tree vlan 1000
    – Ron Trunk
    Jul 2, 2020 at 12:16
  • I'd start by correcting your interface-to-port-channel configurations. Your screenshots indicate each side of the port-channel has two members, but your config pastes show only one. Additionally, your CSR1000V side has traffic but N9K has no traffic. Without knowing more, we cannot rule out a cabling mistake. Enabling LLDP and LACP, and verifying the connectivity between devices, would be good next steps. Jul 2, 2020 at 14:08

1 Answer 1


Thank you all for your comments. The original topology has two routers and two Nexus switches where I wanted to enable features like VRRP on the L3 level and vPC on L2 among others. However, as issues on both layers started piling up, I downsized features and connections until I came with the a poin-to-point issue that triggered this post.

But as Jeff noted, the Po1 had two members because I forgot to shutdown the connection to the second Nexus switch, so once I turned it down pings were successful.

At this point I guess it's time for me to go back to the drawing board and review all settings. But now I had connectivity between the router and the switch.

Thanks again!

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