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New Member

CSS 11501 multiple IPs


We have a CSS setup with only one ethernet port(eth1) ,one arm configuration.

This port is ingress aswell as egress for loadbalancing traffic.

It takes in client request from various sources and load balances to services on the same network.

For E.g is VIP and it load balances to servers located at and

Due to high network traffic we are looking to increase the ehternet links capacity.

I understand we cannot do etherchanneling with css.

So is it possible to connect another ethernet link (eth2) on the same vlan and recieve

client traffic on it for a new VIP for e.g as well as keeping on eth1

Or STP will block this port eth2 thinking its a loop?

Any solution?

Many Thanks


Cisco Employee

Re: CSS 11501 multiple IPs

That won't work.

You need to either replace your fastethernet with a Gig link if you're not already using gig interface.

You can then keep your design.

Or you need to split ingress and egress traffic and therefore get rid of one-armed design.


New Member

Re: CSS 11501 multiple IPs

Hi Giles

Thanks for answering ..

About the split ingress and egress design..

Do I just need to configure another eth interface and assign the same vlan to it. Will that split the ingress and egress traffic. or Do i need to do something else.

Much Appreciated.

interface e1

bridge vlan 2

interface e2

bridge vlan 2

Cisco Employee

Re: CSS 11501 multiple IPs

That can be enough if on the switch side, the interfaces are not connected to the same vlan.

So, if you have cat6k======CSS with both link in vlan 2 on css and both link in vlan 2 on cat6k, spanning tree will block one of the link and you did not solve anything.

If you can put the clients in vlan X on the cat6k and the servers in vlan 2, you can then keep the css interfaces (both of them) in vlan 2.

The css will bridge vlan x and vlan 2.

This is ok.


New Member

Re: CSS 11501 multiple IPs

Thanks Gilles.

I will do just that.. i.e put clients in differnt vlan and servers in differnt vlan..