Primary Interface

Unanswered Question
Jun 30th, 2010


I've read the documentation however I'm still a little confused as to what & how the primary interface is used for. It appears that the IP associated with this interface is registered with the CM. In my instance I require the IP associated with Gi2/0 to be registered with the CM and by changing the primary interface I can change this however I'm not sure how this affects WCCP traffic etc. Please see below for my current config.

My Data Centre config is as follows:

2 x Cisco 4507R Core switches

2 x          OE7341

WAE1 is connected to Core1 & WAE2 is connected to Core2. A L2 EtherChannel exists betwen the cores

I'm using WCCP with L2 redirection and IP Forwarding as egress to a HSRP address. Currently Primary Interface is GigabitEthernet 1/0; default gateway is on the same subnet as the primary interface. GigabitEthernet 2/0 is the management interface with static routing in case Gi1/0 goes down.

Currently I can see all redirected WCCP traffic coming in & out of Gi1/0 which I presume is normal with Gi2/0 sitting idle.

Should I re-configure in a way that WCCP traffic comes in via Gi1/0 but returns via Gi2/0... how do I achieve this configuration? Default gate on the Gi2/0 interface?

Thanks in advance for any replies.



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Zach Seils Thu, 07/01/2010 - 06:17

Hi Craig,

As you mentioned, the primary interface is the interface that is used for communication with the Central Manager.  It is also used by the CIFS AO for pre-positioning and by the SSL AO for communication with peer devices.

WCCP choses the lowest IP address to bind to, so you can only influence the interface it uses by configuration of an IP address.

If you want to dedicate interface gi2/0 for management, you should leave the primary-interface set to gi1/0 and set the "Management IP" to the IP address of interface gi2/0.  The "Management IP" is configured on the Activation page for the device in the Central Manager.


craig-allen Fri, 07/02/2010 - 03:57

Hello Zach,

Thanks for the clarification!

How do I re-set the 'Management IP' if the WAE is already registered to the CM? Do I presume correctly I would need to de-register and register again with correct IP?

With regards to the WCCP config; I understand about the ingress redirection in terms of the lowest IP used for registration. Should I leave it as default with traffic being forwarded to default gateway on Gi1/0 interface or is it best tohave ingress on Gi1/0 and then egress on Gi2/0?

Basically I'm just trying to understand the best setup for WCCP using both the Gi1/0 & Gi2/0 ethernet ports



Zach Seils Tue, 07/06/2010 - 06:22


You should be able to change the management IP address while you are registered with the CM.  It may take a couple of cycles to update, but it should update on its own.

With regards to WCCP, you should use a single interface for both ingress/egress traffic.  If you need to use multiple interfaces for redundancy, consider using the Standby Interface of PortChannel features.




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