Portchannel one side L3 interface and other side L2 interface

[raghav.rai]

Hi All,

Pleas refer the attached diagram. I have a requirement to create redundancy between a 6509 and an ASR-1k (which acts as a server) by having 2 physical links between them. Also I will have to use an IP from the existing vlan in 6509 (VLAN-100). Is it possible to bundle them using port-channel and then configure IP only at router end of the port-channel. Switch end of the port-channel will act as Layer-2 port channel as shown in the diagram.

Or is there any other good solution that you can suggest?

Thanks,

Raghavendra

[Julio E. Moisa]

Hi

Unfortunately, it is not possible, on portchannel both ends must be have the same configuration. Is this SVI 100 on the 6509 used for other role or just to connect with the ASR?

[raghav.rai]

Thank you Julio.

Yes, SVI 100 is used as default gateway for a set of users. One IP from vlan 100 subnet needs to be sued to extend connectivity to this ASR router. Is there any other option like creating BVI interface in ASR router ?

[raghav.rai]

Any other solution for this requirement ? How about BVI ? Can I terminate it on a BVI interface of ASR router?

[Jon Marshall]

I think your original solution should work fine although I have never used that setup with an ASR. 

I have used a similar setup in the past where the 6500 was running CatOS which meant you could not configure L3 physical ports so you configured a L2 etherchannel with the physical ports in a vlan and then have an SVI for that vlan on the 6500 just as you are proposing. 

The other end of the link was a L3 etherchannel and it worked fine.

Jon

[raghav.rai]

Thank you Jon.



We tried testing it in a GNS set-up but it didn't work. How about creating a BVI interface on the router will it work ?

[Jon Marshall]

Haven't tried that. 

What part did not work ie. did the etherchannel not come up or did it not pass traffic ?  

I have definitely used that setup before but it was between switches at both ends so it looks like Julio may well be right. 

Jon

[raghav.rai]

In GNS-3 port-channel itself is not coming up when we have IP address at one end. When it is Layer-2 at both the end and Layer-3 at both the end port-channel is coming up.

[Jon Marshall]

Did you set both ends to on ?

I know it works between switches because I have done it and advised people on this forum that it works and they have confirmed it so perhaps it is to do with the ASR. 

Apologies for misleading information.

Jon

[raghav.rai]

Hey No worries, your inputs will definitely help. I will try again by making it on at both the end

[axeleratorcisco]

Looking for a similar setup.

I have a Catalyst switch which I want to connect redundantly to two Nexus switches. The Nexus switches connect to a firewall cluster.

Is it possible to create an L3 port channel on the catalyst, a L2 VPC on the Nexus side, and extend the VLAN towards the firewall?

In essence i want 1 VLAN between the Catalyst and firewall. Whereby I can ping from the routed interface on the Catalyst, to the ip address on the firewall cluster.

Note: the setup looks just like the attached drawing in this post, only difference is I don't want to ping the SVI on the 6500, but I would like to ping the WAN MPLS router (which in my case is the firewall).