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ovt Bronze
Bronze

Hierarchical QoS with IPSec

Hi!

Could anybody help me understand the following example taken from cisco.com (DMVPN SRND) and mentioned there as a "best practice":

class match-any voice

...

class match-any mission-critical

...

! Other classes

policy-map my-policy

class voice

priority percent 20

class mission-critical

priority percent 40

class other

bandwidth ...

class class-default

fair-queue

policy-map my-shaper

class class-default

shape average 256000

service-policy my-policy

interface fa0/0

service-policy output my-shaper

Shaping is used here because not all bandwidth of fa0/0 is available (ISP polices our traffic). Inside the shaper voice and mision-critical classes should have priority treatment.

Unfortunately it simply doesn't work (IOS 12.4(5)). ALL traffic classes are shaped equally. ALL packets (voice, data, etc.) go to the shaper buffers in FIFO order (!), delayed there (!) and then processed by the inner policy-map (my-policy). Policy-map my-shaper has no idea about priorities of classes in the inner policy-map (my-policy). This is not good for voice, to say the least.

I've verified this with IPSec (DMVPN) and without IPSec configured, so this is not an IPSec problem, it is the QoS problem.

Can anybody tell me is this a bug or feature? Are there workarounds?

Also, does anybody know why is "match protocol" not working with IPSec qos-preclassify feature ("match access-group" works well)? So far as I know "match protocol icmp" doesn't mean that NBAR (which is not supported with IPSec) must be used by the router to classify traffic. In this simple case the router can classify traffic by Protocol field in the IP header, right? Am I mistaken?

Thx,

Oleg Tipisov,

REDCENTER

1 REPLY

Re: Hierarchical QoS with IPSec

Hello Oleg,

I assume the second post with nearly the same content answered most of your questions.

Just to note: "match protocol" with any protocol mentioned IS using NBAR. You are right one could detect ICMP by other means than NBAR on a router, but the command "match protocol icmp" is instructing the router to use NBAR for protocol classification.

As you already know it is currently not supported with IPSec and therefore can not be used in your environment.

Hope this helps! Please rate all posts.

Regards, Martin

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