Routing
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Routing

question on auto bandwidth

‎08-15-2014 04:53 PM

Hi,

 

Can you help me. I don't know why the lsp did not switch to secondary path. I have two streams of IPv4 traffic come in the router (see the configuration below). One stream will go to to_bravo. Other will go to to_titanic.

Each stream is 6Gig. I expect the stream of to_bravo will switch to secondary path because maximum-bandwidth is only 3 Gig. But it did not. I don't know why? Thanks for your help.

 

routing-options {

    static {

        route 22.1.1.0/24 {

            lsp-next-hop to_bravo;

        }

        route 33.1.1.0/24 {

            lsp-next-hop to_titanic;

        }

    }

}

protocols {

    rsvp {

        interface all;

        interface em0.0 {

            disable;

        }

    }

    mpls {

        statistics {

            file mpls.stats;

            interval 60;

            auto-bandwidth;

        }

        label-switched-path to_titanic {

            to 10.255.176.57;

            auto-bandwidth {

                adjust-threshold 10;

                minimum-bandwidth 1m;

                maximum-bandwidth 6g;

            }

            primary path1;

            secondary path2;

        }

        label-switched-path to_bravo {

            to 10.255.176.161;

            auto-bandwidth {

                adjust-threshold 20;

                minimum-bandwidth 1m;

                maximum-bandwidth 3g;

            }

            primary path1;

            secondary path2;

        }

        path path1 {

            100.1.1.2 strict;

        }

        path path2 {

            100.2.2.2 strict;

        }

        interface all;

        interface em0.0 {

            disable;

        }

    }

 

Sincerely,

Tet

 

4 REPLIES 4
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Routing

Re: question on auto bandwidth

‎08-20-2014 10:05 AM
Hi Tet,

The value of "maximum-bandwdith" is used as a ceiling limit when the LSP is re-signalled after the auto-bw computation. Meaning that even if the auto-bw computation yields the utilization as 4g or 6g, the LSP will be signaled with bandwidth-requirement of nor more than 3g.

You can check the same using

show mpls lsp name to_bravo extensive

If the re-signalled LSP is successful, then there would be no reason for LSP to switchover.

Regards
Surya
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Routing

Re: question on auto bandwidth

‎08-21-2014 03:59 AM

The mpls statistics allows the collecting of LSP statistics.

The auto-bandwidth will make your LSP resignal itself every 86400 seconds (default value but can be adjusted with adjust-interval keyword).

If the statistitics determine that your flow is 4G then the new LSP will be resignalled and reserve 4G. Another example: if the statistitics determine that your flow is 7G  then the new LSP will be resignalled and reserve only 6G. This is the purpose of the keyword maximum-bandwidth 6g.

In any case a LSP is policed and traffic is dropped or redirected should the flow exceed the value of reserved bandwitdh.

 

Also a secondary path is just an alternative path in case the primary path cannot be up because of link or router failures. In any case it is related to flow capacity or policing.

 

 

 

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Re: question on auto bandwidth

‎08-21-2014 07:11 AM

>>> In any case a LSP is policed and traffic is dropped or redirected should the flow exceed the value of reserved bandwitdh.

 

I am afraid to state that the above is incorrect. The bandwidth constraint included in RSVP path T-Spec object is used only for reservation and not for data policing. You would need COS to implement the policing on the data.  

 

Regarding the max-bw, please refer below:

 

http://www.juniper.net/techpubs/en_US/junos13.2/topics/usage-guidelines/mpls-configuring-automatic-b...

 

Regards

Surya

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Re: question on auto bandwidth

‎08-21-2014 07:47 AM

 

This is what I wanted to write. Sorry for my poor english. Replace "in any case" with "under no cirumstances" in the sentence you quoted.

 

« Under no circumstances a LSP is policed and traffic is dropped or redirected should the flow exceed the value of reserved bandwidth »

 

I think now this sounds better.