RE: real world QOS issue

From: Tony Schaffran \(GS\) (groupstudy@cconlinelabs.com)
Date: Tue Mar 11 2008 - 17:32:34 ARST


Actually, I just caught a fundamental problem with your sample config.
 
If you do not specify match-any or match-all in your class-map, the default
is match-all which means that a packet would need to match kazaa, bittirent
and access-list 101 to be in class junk. No packet would match that
criteria.
 
You need to configure a class-map match-any junk with your criteria and then
the packet that matches any one of them would be flagged for drop in your
policy-map.
 

Tony Schaffran

Network Analyst

CCIE #11071

CCNP, CCNA, CCDA,

NNCDS, NNCSS, CNE, MCSE

 

www.cconlinelabs.com

Your #1 choice for online Cisco rack rentals.

 

 

  _____

From: Joseph Brunner [mailto:joe@affirmedsystems.com]
Sent: Tuesday, March 11, 2008 1:04 PM
To: 'Edward Balow'; groupstudy@cconlinelabs.com; 'groupstudy'
Subject: RE: real world QOS issue

I have had issues (perhaps someone can elaborate)

 

Where say you are doing this.

 

access-list 101 remark edonkey

access-list 101 permit tcp 10.1.1.0 0.0.0.255 any eq 4672

 

Class-map junk

Match protocol kazaa

Match protocol bittorent

Match access-group 101

 

Policy-map inbound

Class junk

Drop

 

Int F0/0

Service-policy input drop

 

Dropping TCP 4672 DOESN'T WORK. but if you do this.

 

 

Class-map junk_mark

Match protocol kazaa

Match protocol bittorent

Match access-group 101

 

 

Policy-map inbound

Class junk_mark

Set dscp cs1

 

Int F0/0

Service-policy input inbound

 

Then (now I marked it with dscp, cause it's going to be natted to different
ip's outbound.. and we cant match ip source so easily,

But we can match dscp)

 

Class-map junk

Match dscp cs1

 

Policy-map outbound

Class junk

Drop

 

Interface s0/0/0

Service-policy output junk

 

IT WORKS!

 

ALL TCP to 4672 and the other stuff that was MARKED CS1 inbound on F0/0 is
DROPPED.

 

It was another policy dropping CS1 out of F0/0 that killed my clients sites.

 

So my question is.

 

What causes the DROP option to ONLY work when traffic is LEAVING an
interface????

(I had this happen a lot last year with my policies to "drop all images from
a url, but permit the site itself) the traffic had to be dropped on router
egress to work!!!

 

Thanks,

 

Joe

 

 

  _____

From: Edward Balow [mailto:ebalow@hotmail.com]
Sent: Tuesday, March 11, 2008 1:55 PM
To: Joseph Brunner; groupstudy@cconlinelabs.com; 'groupstudy'
Subject: RE: real world QOS issue

 

Why bother to mark stuff you want to drop? You're marking at the edge. Why
would you want traffic you're eventually going to drop to eat up internal
resources before being dropped at distribution? Don't mark it as anything,
just drop it.

> From: joe@affirmedsystems.com
> To: groupstudy@cconlinelabs.com; ccielab@groupstudy.com
> Subject: RE: real world QOS issue
> Date: Tue, 11 Mar 2008 14:41:47 -0500
>
> Yeah, duh, I'm dumb...
>
> (no wonder I'm going for 3 more stars, so I can learn something)
>
> What I did in my little qos world was use CS1/Scavenger as a place to put
> stuff I wanted to drop anyway (like kazaa, bittorrent, etc)
>
> So what is the recommended dscp for stuff you REALLY do want to drop, even
> if there is NO congestion...
>
> Thanks,
>
> Joe
>
> -----Original Message-----
> From: Tony Schaffran (GS) [mailto:groupstudy@cconlinelabs.com]
> Sent: Tuesday, March 11, 2008 1:24 PM
> To: 'Joseph Brunner'; 'groupstudy'
> Subject: RE: real world QOS issue
>
> You would normally not drop scavenger class unless you are experiencing
> congestion.
>
>
> Tony Schaffran
> Network Analyst
> CCIE #11071
> CCNP, CCNA, CCDA,
> NNCDS, NNCSS, CNE, MCSE
>
> www.cconlinelabs.com
> Your #1 choice for online Cisco rack rentals.
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Joseph Brunner
> Sent: Tuesday, March 11, 2008 9:45 AM
> To: 'groupstudy'
> Subject: real world QOS issue
>
> Can anyone tell me why Sungard (and I know several of you guys work for
> them) would mark data from their websites with CS1 ???!?!?!?!?
>
>
>
> What are you thinking? That is the scavenger class in many books and it's
> frequently used in the real world to mark JUNK (to be dropped later).
>
>
>
> Just today I solved an issue where a client couldn't get to a few big
firm's
> website. Turns out they are all hosted on Sungard.
>
> I had to temporarily disabled the scavenger class's drop setting
>
>
>
> policy-map somepolicy
>
> class scavenger
>
> drop
>
>
>
> interface f0/0
>
> service-policy output somepolicy
>
>
>
> Take this capture image from example law firm, www.shearman.com
> <http://www.shearman.com/>
>
>
>
> http://img364.imageshack.us/my.php?image=shearmanyo5.jpg
>
>
>
>
>
> Can anyone explain this!!!
>
>
>
> Thanks,
>
>
>
> Joe
>
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  _____

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