From: Huan Pham (pnhuan@yahoo.com)
Date: Thu Nov 13 2008 - 18:41:21 ARST
Pavel,
You're correct! Thanks for the correction. I did not notice that, even if I
try to put class-default in front of other, it's automatically listed last. I
was just discussing the general "oder of operation" in QoS using a MQC
policy-map.
Cheers,
--- On Fri, 11/14/08, Pavel Bykov <slidersv@gmail.com> wrote:
From: Pavel Bykov <slidersv@gmail.com>
Subject: Re: FR-DE in class-map
To: huan@huanlan.com
Cc: "backbone systems" <backbone.systems@gmail.com>, "Cisco certification"
<ccielab@groupstudy.com>
Date: Friday, November 14, 2008, 6:30 AM
Huan Pham, your statement would be true if the class was not class-default.
"class-default" is a system class and cannot be deleted or put ahead of other
classes.
Also, it can never have a match statement - it will always match everything.
This is easy to test - it can not be even created:
Router(config)#class-map class-default
% class-default is a well-known class and is not configurable under class-map
Therefore having classes under it would not have any point. So you have to
remember that "class-default" is an IMPLICIT class at the end, just like deny
statement at the end of every ACL, prefix list and AS-PATH ACL, deny clause at
the end of every in every route-map etc. But it does not deny all, it MATCHES
ALL.
P.S.: you can also create a class-map with "match any" statement that would
match anything and therefore class-default would not receive any packets. But
you still can never get rid of class-default.
Note: all above is true for MQC
On Thu, Nov 13, 2008 at 1:35 PM, Huan Pham <pnhuan@yahoo.com> wrote:
Hi,
Whenever a policy-map is binded to an interface, traffic leaving or comming to
that interface (depending on the policy-map applied outbound or inbound) will
be examined in the order of classes in which they are listed. Whenever
traffic gets a positive match on a class, action takes place, then traffic
will not be matched again the next class.
In your case, class X will not be marked with DE. All other traffic will be
marked.
However, if you change the order of classes in your policy-map, i.e.
policy-map X
class class-default
set fr-de
class X
! no action
then all traffic will be positively matched again class class-default, so ALL
will be marked with DE, including traffic that normally matches class X
itself.
If you do "show policy-map interface" in this case, you wont see any traffic
hitting class X at all.
Whether getting marked with DE bit will be dropped before other traffic in
the core is another story. If your Frame-Relay provider trust your marking and
implements such a dropping policy, then the answer is YES.
If they do not implement a dropping policy based on DE, then, all traffic is
treated the same: John Chamber's or Level1 engineer's!
On Thu, Nov 13, 2008 at 6:41 AM, backbone systems <
backbone.systems@gmail.com> wrote:
> For the following config,
>
> class-map X
> match access-group 101
>
> policy-map X
> class X
>
> class class-default
> set fr-de
>
> map-class frame-relay Y
> service-policy output X
>
>
> int ser1/0
> frame-relay interface-dlci 501
> class Y
>
> Now my question is that wen it comes to droping of traffic ....the
> traffic in the class-default is DE marked ...wat policy will be
> followed for the traffic in "class X"...will it not be droped
before
> all the other traffic?For the class X there is not set statement..
>
> thanks
>
>
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-- Pavel Bykov ------------------------------------------------- Stop the braindumps! http://www.stopbraindumps.com/Blogs and organic groups at http://www.ccie.net
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