Class-based Shaping

Unanswered Question
Mar 4th, 2009

Hello All

Just wanted to confirm if I can use shaping to restrict bandwidth for incoming traffic with "service policy in" ? As far as I know, with GTS bandwidth restriction is possible only for outbound traffic, and i'll have to use policing (CAR) to do inbound bandwidth limitation.. right ?

With my scenario, i'm trying to restrict EoIP traffic for guest users going to internet through a POP over WAN.. scenario is like this

LOC A - WLC - ROUTERA - P2P - ROUTER B - Anchor - Internet

which is the best point to apply traffic shaping in this scenario, to restrict both incoming and outgoing traffic, so that my WAN P2P link allows only 1.5 Mbps of traffic through it (both directions)

I have this problem too.
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adamclarkuk_2 Wed, 03/04/2009 - 08:30

In my humble opinion, it is never worth shaping/policing once you already have the traffic. Always mark inbound and police / shape outbound on an interface.

sblavanya Wed, 03/04/2009 - 09:25

Hello Adam

Thanks for the response.

what do you mean by "it is never worth shaping/policing once you already have the traffic" ?

issue here is forward traffic to internet is from Location A and return traffic comes back from Location B, where the internet exit point is..

and.. will service policy input, with shaping work on inbound direction ?

Joseph W. Doherty Wed, 03/04/2009 - 09:40

Unclear what you're trying to accomplish. If you control both routers A & B, best solution might be to shape outbound on both those routers and limit traffic to 1.5 Mbps.

PS:

You can't use a shaper inbound, only a policer.

sblavanya Wed, 03/04/2009 - 09:58

Hello Joseph

I'm basically trying to restrict guest traffic through EoIP, across WAN. browsing traffic is now open, and traverses across the WAN, over IP 97.. I'm trying to cap this traffic to 1.5 Mbps , for both outbound and inbound..

So, I cannot use a Class based shaper for restrictig inbound traffic right ?

we didnt want to do outbound shaping, because the routers already have too many classes, and the customer doesnt want to add one more class for GUEST traffic.. Would a normal GTS work here ?

Joseph W. Doherty Wed, 03/04/2009 - 12:02

"So, I cannot use a Class based shaper for restrictig inbound traffic right ? "

Correct, but you can use a class based policer. Again, keep in mind, a downstream policer will not insure the upstream bandwidth is capped. You only fully control bandwidth downsteam of the policer (or shaper).

"we didnt want to do outbound shaping, because the routers already have too many classes, and the customer doesnt want to add one more class for GUEST traffic.. Would a normal GTS work here ? "

Not 100% sure, but I thought GTS would shape all traffic, and you only want to cap some traffic? Also, there's no policy on the interface now? (I.e. not sure GTS is supported with something like CBWFQ.)

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