WAAS placement query

Answered Question
Aug 25th, 2008

Dear All,

I wanted to clarify some concepts regarding WAAS placement.

Scenario:

We have a scenario with different vlans in a core switch with SVIs as gateway for hosts.

The core Switch is connected to core router interface using vlan1 since there are no routed ports in switch,all the vlans traffic is routed to the vlan1 to reach the router.

But some networks in the Switch are not in vlans and are by default in vlan1. The router interface has secondary ip addresses configured since its is acting as a geteway for these networks not in the vlans.

In short router interface which is connected to vlan1 of the switch is the only outgoing interface for the network.

Question:

Now in this mixed scenario where should the redirection be applied. Since router LAN interface is the gateway for other networks not in vlans and not the switch vlan1 SVI then we cannot apply redirection on SVI interface.

Is it possible to apply redirection on router LAN and WAN interfaces? IF yes then, can we put the WAAs box in vlan1 network? Will it optimized traffic for other vlans or for networks for which router has secondary ip addresses?

Waiting for any sort of help.Thanks

I have this problem too.
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Correct Answer by ropethic about 8 years 3 months ago

Customers repeatedly asked Cisco to change the requirement for a separate subnet / interface. the redirect exclude in was needed when using a separate interface to prevent optimized traffic from being redirected.

in 4.0.13 the requirement for extra subnet was removed and wae can now be placed on user vlan.

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ropethic Tue, 08/26/2008 - 04:04

if using an inline adapter on the WAE, then placement between router and switch with "inline vlan all" set on the inline interface will provide optimization for incoming traffic to the router.

A diagram of network would be helpful.

For WCCP you can create another vlan on the switch and have traffic redirected to this vlan. On the wae wccp router list 1 will point to the gateway of the new vlan svi.

Placing it on vlan 1 will work as well. user traffic is transparent and will be redirected to the WAE regardless of source / destination. Set ip wwcp 61 in on the router ether interface and ip wccp 62 on wan side.

I would rethink the use of numerous secondary addresses. The main negative in using secondary addresses is that it does not contain broadcasts and multicasts on that network. In most cases, the router and workstations can handle broadcasts from two or three subnets, but it is not a good idea to stack several subnets together on a single interface or the network will seem to slow down.

Tahir Ali Tue, 08/26/2008 - 05:49

one thing i forgot to ask is that my WAN have primary and redundant DMVPN tunnel towards branches with two SPs. Will it have any effect if I apply wccp 62 in on tunnel interfaces? Any asymetric routing issue?

ropethic Tue, 08/26/2008 - 08:35

WCCP not supported on tunnel interfaces for 6500 & 7600 interfaces. Other than that okay.

see below.

Cisco WAAS supports asymmetric routing through the use of sharing network interception and redirection configuration across WAN boundary routers within a location. If all routers that connect a location to the WAN are participating in the same WCCPv2 service groups or have the same list of WAEs configured as next-hop routers (in the same order), the same WAE will receive redirected traffic regardless of the WAN link that traffic was destined to or coming in from.

For instance, if a customer has two WAN connections - one going to provider #1 and another going to provider #2, WCCPv2 can be configured such that the routers participate in the same WCCPv2 service groups, and the WAEs can be configured to register with both of the routers. This also requires that the WCCPv2 redirection configuration be applied identically across each of the routers within the same location, i.e. use of 61/in on the LAN side on both routers and 62/out on the LAN side on both routers (or any valid combination of 61/62 in/out as long as they are identical amongst all routers within the location).

As traffic enters a WAN boundary router, it will determine which WAE to redirect the traffic to based on a hash of either the source IP (service group 61 in the network path) or destination IP (service group 62 in the network path). The allocated hash buckets are synchronized within the service group, and the hash value obtained at either router will be the same as it would be had the traffic been forwarded through the opposite router. In this way, traffic is always redirected to the same WAE every time, regardless of which WAN link is used, or which router the traffic was forwarded to or through. As such, Cisco WAAS provides support for environments where asymmetric routing may be encountered.

Tahir Ali Tue, 08/26/2008 - 09:41

Thanks very much for your help, it really cleared some issues in mind regarding WAAS integration.

Last question which wasn't answered in my first post is what difference does it have of having WAAS in seperate VLAN or in common vlan within the LAN network, except that we have some basic vlan benfits?

And

when do we put the redirect exclude in command. In one of the guide it had that command configured when WAAS was in separate VLAN,and we have both redirect 61 and 62 in IN direction.

In another book i read that when we use redirect in out direction we need to have this command. So why and when do we exactly need this command.

Correct Answer
ropethic Tue, 08/26/2008 - 11:54

Customers repeatedly asked Cisco to change the requirement for a separate subnet / interface. the redirect exclude in was needed when using a separate interface to prevent optimized traffic from being redirected.

in 4.0.13 the requirement for extra subnet was removed and wae can now be placed on user vlan.

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