One Armed Config for multiple C classes

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Sep 2nd, 2010
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I am trying to implement one armed config in the existing network for several c classes.  Do I need to configure multiple Circuit vlan IP addresses corresponding to different C classes or one Circuit VLAN IP is sufficient.

Can I configure VIP in a different C class than Circuit VLan IP.

I intend to use Source groups to get the traffic from servers back to CSS.

Many thanks in advance.


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Andrew Nam Thu, 09/02/2010 - 18:29
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Two options are all ok.

1. The CSS will allow you to create a secondary address on the circuit.

for example,

circuit VLAN2

ip address

ip address

2. You could also create another interface "circuit" on the CSS and assign it with  the new subnet IP. Then trunk the vlan to core network.

If you uses one arm mode, then you can use either source "groups" to get the traffic from servers back to CSS or PBR from switch.

You can configure VIP in a different C class than Circuit VLan IP. However, you need to control the routing tables of all other devices. Generally speaking, I would not recommend this setup to the customer.

virtualoffis Sun, 09/05/2010 - 03:02
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Thanks heaps..

I have done this part and also created multiple default gateways...per  class..this was required to get it going.

Another question...out of these multiple default gateways...CSS will use which to go to internet for CSS originated traffic. Is it like first one.

i have x.x.x.x y.y.y.y

where x and y are default gateways for 2 different C classes.

Thanks in advance..

Andrew Nam Sun, 09/05/2010 - 17:43
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it would load balance between them. However, the global config command "ip ecmp" governs this.

CSS11150(config)# ip ecmp ?
address             Choose among alternate paths based on IP addresses
roundrobin          Alternate between equal paths in a roundrobin

Perhaps, below link explains in detail for your question :


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