2248 Fabric Extender Dual-Connected to Two Cisco Nexus 5548

[jahanzaib amin]

Dear Expert,

I am trying to deploying Dual-Connected to Two Cisco Nexus 5548 with 2248 Fabric Extender. But i am facing an issue when I create VPC between

5548 and 2248 then the Fex disappear and i couldn’t see the Fex in "Show Fex command". Further I have using Single connection from Each Nexus 5548 to both Fex 2248. (See attached Diagram).

But the issue is when I create VPC on nexus side the Fex is disappearing and I couldn’t see any output “show Fex". Kindly see my attached Configuration for both Nexus 5548 and suggest where the issue on config side is.

Further In attached design the both Nexus 5548 are active and can manage the FEX from any one so How i can make proper synchronization between them. Kindly provide some proper Cisco documentation guide to accomplish this task.

[Mandlenkosi Nkiwane]

I would change the configuration on either A or B so that the config is consistant on both 5548's.

Switch A

interface Ethernet1/2
  switchport mode fex-fabric
  fex associate 100
  channel-group 60

Switch B

interface Ethernet1/1
  switchport mode fex-fabric
  fex associate 100
  channel-group 60

If these are syncing configs, then you might have a mess in your hands..

I would rather have the same interface # on the same port-channel # on both switches...

HTH,

[jahanzaib amin]

Dear Folks,

Let me review your suggestion and reapply again to attach diagram scenario. But in this scenario how we can syn the both control plan of Nexus 5548? Because from any one of the NK5548 I can see the FEX interfaces of both Nexus 2248 so If i make changes from Nk5548-A then how the change will syn to NK5548-B?

Please advice.

Further I tried a lot to get some configration document regarding the dual connection (attached Diagram) but I could'nt find on cisco can you send me the link information for Dual Home connection VPC

Thanks,

Jehan

[Mandlenkosi Nkiwane]

First and foremost  you have to bring up the peer-link.

Secondly you need the following:

Switch A

switch-profile switch1
  sync-peers destination 10.10.10.2

Switch B

switch-profile switch1
  sync-peers destination 10.10.10.1

For your Switch B it seems you did not complete the config of the peer-link interfaces: You need to have it look like this:

interface Ethernet1/15
  description TO NK5548-A
  switchport mode trunk
  speed 1000
  cchannel-group 50 mode active

interface Ethernet1/16
  description TO NK5548-A
  switchport mode trunk
  speed 1000
  channel-group 50 mode active

HTH...

[jahanzaib amin]

Dears,

Thanks for point-out the issue. I will correct it and come back to you again.

Best Regard,

Jehan

[Steve Fuller]

Hi Jehan,

The following should get you working:

N5548-A

N5548-B

! feature lacp feature vpc feature fex ! vpc domain 55   role priority 8192   system-priority 8192   peer-keepalive destination 10.10.10.2   delay restore 150   auto-recovery ! interface Ethernet1/15   description TO NK5548-B   switchport mode trunk   speed 1000   channel-group 50 mode active ! interface Ethernet1/16   description TO NK5548-B   switchport mode trunk   speed 1000   channel-group 50 mode active ! interface port-channel50   switchport mode trunk   spanning-tree port type network   speed 1000   vpc peer-link !

! feature lacp feature vpc feature fex ! vpc domain 55   role priority 9192   system-priority 8192   peer-keepalive destination 10.10.10.1   delay restore 150   auto-recovery ! interface Ethernet1/15   description TO NK5548-A   switchport mode trunk   speed 1000   channel-group 50 mode active ! interface Ethernet1/16   description TO NK5548-A   switchport mode trunk   speed 1000   channel-group 50 mode active ! interface port-channel50   switchport mode trunk   spanning-tree port type network   speed 1000   vpc peer-link !

At this point you should be able to run the show vpc command and see that the peer status shows as "peer adjacency formed ok", the vPC keepalive status shows the peer as alive, the peer-link is up etc.

Once you have the vPC up and working then you can add the dual homed FEX as follows:

N5548-A

N5548-B

! fex 100   pinning max-links 1   description "FEX0100" ! interface port-channel60   switchport mode fex-fabric   fex associate 100   vpc 60 ! interface Ethernet1/1   switchport mode fex-fabric   fex associate 100   channel-group 60 ! fex 101   pinning max-links 1   description "FEX0101" ! interface port-channel61   switchport mode fex-fabric   fex associate 101   vpc 61 ! interface Ethernet1/2   switchport mode fex-fabric   fex associate 101   channel-group 61 !

! fex 100   pinning max-links 1   description "FEX0100" ! interface port-channel60   switchport mode fex-fabric   fex associate 100   vpc 60 ! interface Ethernet1/1   switchport mode fex-fabric   fex associate 100   channel-group 60 ! fex 101   pinning max-links 1   description "FEX0101" ! interface port-channel61   switchport mode fex-fabric   fex associate 101   vpc 61 ! interface Ethernet1/2   switchport mode fex-fabric   fex associate 100   channel-group 61 !

Because from any one of the NK5548 I can see the FEX interfaces of both Nexus 2248 so If i make changes from Nk5548-A then how the change will syn to NK5548-B?

By default the configuration is not synchronised between the two switches, but you have two options:

1. Manually apply the exact same configuration to both switches.
2. Use the configuration sync feature as described in the Configuration Synchronization Operations document.

As mentioned previously, from an operational and management standpoint it's probably best to maintain consistency of the interface you use to connect to the FEX i.e., if FEX 100 is connected to N5548-A eth1/1, then also connect it to eth1/1 on N5548-B. Strictly you don't have to do this if you manually apply the configuration to both switches, but you must have consistency if you use the configuration synchronisation feature.

My personal preference is to manually apply the configuration to both Nexus 5K rather than use config-sync. It's not a huge burden and I've seen and read of a number of issues with bugs in config-sync.

Regards

[Steve Fuller]

Hi,

The first thing you need to address is the fact that your peer-link is down. If you don't have the vPC peer-link operational then you'll never get other vPC working, including those to the FEX.

When I look through the configuration of NK5548-B I can see that you've created interface port-channel 50 and assigned the vpc peer-link command to this interface, but I don't see any physical interfaces configured as members of that port-channel i.e., with the channel-group 50 mode active command as you have configured on NK5548-A Ethernet 1/15-16.

Regards