Multilink issue

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Feb 18th, 2009
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hi all,

as we change bw on multilink interface it won't allow unless it is shutdown.

sometimes we get request from customer to increase bw of multilink which require downtime.

is there any work around ? if i don't put bw command is it good practice



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Giuseppe Larosa Wed, 02/18/2009 - 10:34
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Hello Mahesh,

I may have misunderstood.

When the customer asks for more bandwidth are you changing the bandwidth command ?

or more probably are you changing bandwidth in a policy-map applied to the multilink interface.

The first is useless from the point of view of the user.

bandwidth command is just there for routing protocols and Modular qos

The second if you are policing traffic makes the difference.

Or are you adding a new link to the bundle ?

May you explain in more detail what actions you apply to the multilink bundle.

Hope to help


mahesh-gohil Wed, 02/18/2009 - 20:33
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ya Giuseppe,

actually when we receive request bw upgrade or downgrade on existing multilink we change bw command and also qos (may be sometimes multiple qos).

only pain area is to change bw command we need to shut the link which is useless as per your guide.

actually i am thinking to configure BW command as some definite value (say 16mb or 20mb regardless of no. of link the multilink is part of ) at the first that next time for any changes i don't require to plan downtime.

does this have any effect if if qos is also configured on this link.

please guide


Giuseppe Larosa Thu, 02/19/2009 - 00:06
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Hello Mahesh,

if in QoS you use command like

priority percent

bandwidth percent

the interface command bandwidth provides the reference value for those percentages (actually the ref is max-reserverved-bw * bandwidth = 75% of bandwidth command)

So I understand why you change it.

so the best thing to do to minimize problems is:

to keep bandwidth command at an high value that reflects the actual speed and number of physical links.

when you receive a customer request to increase its bandwidth you go to

policy-map -> class-map

and you change the bandwidth percent here

this should be possible without shutting down the bundle

Hope to help


mahesh-gohil Thu, 02/19/2009 - 00:36
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Ok happy with your reply

Now what i am looking for is even if i add new link to this bundle there should not be any downtime activity just to minimise downtime at provider end.

can i go ahead to configure bw as some definite value (say 6 or 8 link which is supported at cisco in multilink ) so can i go for 12mb or 16mb bw command

thanks again



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