I have a question that How PBR works?

Answered Question
Jul 6th, 2009
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Hi.


I wonder that the PBR How it works at CCO as following:


"If the packets do not match any route map statements, then all the set clauses are applied."


the pbr works step-by-step. for example


route-map korea 10

match access-group 10

set ip precedence 30


route-map korea 20

match access-group 20

set ip precedence 31


route-map korea 30

match access-group 30

set ip precedence 32


and then Implicited Denied ,because of route-map rules. Right?

If packet is no match route-map rule,then the packet is processed normal switching not process.


but above statement. if the packet do not match any route-map statments, then all the set clauses are applied.

I can't understand above statement. if the packet do not match any route-map statement, the packet is just normal

processing, but the statement at cco says all set are applied.. <- Wrong Statement?


if right , Let me understand about this.

Thank you in advance

Correct Answer by Richard Burts about 7 years 11 months ago

Sung


The statement that you quote does not seem correct to me. I wonder if it is discussing some specific circumstance or perhaps is just an error in the documentation. A special circumstance might be something like an instance within the route map which does not have a match statement and has only a set statement like this:

route-map korea 40

set ip precedence 32

in this case there is no statement to match and all set statements are executed.


Perhaps if you post the link to where you find this statement we can help find out whether there is some special circumstance it is discussing or whether it is an error in documentation.


HTH


Rick

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Istvan_Rabai Mon, 07/06/2009 - 20:55
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Hi,

It may be some mistyping.


If the packet does not match any route-map statements, then it is routed per the contents of the IP routing table.


In this specific case the packets are routed per the IP routing table when the packets match any route-map statement.

This is because you only set the IP precedence of the packets, and you do not set either the ip next-hop or the outgoing interface.


Cheers:

Istvan

syjeon Mon, 07/06/2009 - 21:07
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yes, You are right.

the packet is setted the ip precendence value and processing next destination by referencing normal ip routing table.


the most thing I wonder is..

the statnement from cco, What is mean like below?


If the packets do not match any route map statements, then all the set clauses are applied


Correct Answer
Richard Burts Mon, 07/06/2009 - 22:01
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Sung


The statement that you quote does not seem correct to me. I wonder if it is discussing some specific circumstance or perhaps is just an error in the documentation. A special circumstance might be something like an instance within the route map which does not have a match statement and has only a set statement like this:

route-map korea 40

set ip precedence 32

in this case there is no statement to match and all set statements are executed.


Perhaps if you post the link to where you find this statement we can help find out whether there is some special circumstance it is discussing or whether it is an error in documentation.


HTH


Rick

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