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Why we configure bandwidth value to a interface?

DuJin0509
Level 1
Level 1

Hello everyone,

Why we configure bandwidth value to a interface ? Is it possible to utilize this value to rate limit ?

If I adjust the bandwidth for a one gig ethernet interface from 1000 to 10, what is the real transit capacity for this interface now?

Thank you very much.

1 Accepted Solution

Accepted Solutions

Mark Malone
VIP Alumni
VIP Alumni

Hi

the bandwidth statement is only for the actual IGP routing protocol to calculate the correct metric , it does  not effect the bandwidth of the physical interface

http://www.cisco.com/web/techdoc/dc/reference/cli/nxos/commands/l2/bandwidth__interface.html

Usage Guidelines

The bandwidth command sets an informational parameter to communicate only the current bandwidth to the higher-level protocols; you cannot adjust the actual bandwidth of an interface using this command.

View solution in original post

3 Replies 3

Mark Malone
VIP Alumni
VIP Alumni

Hi

the bandwidth statement is only for the actual IGP routing protocol to calculate the correct metric , it does  not effect the bandwidth of the physical interface

http://www.cisco.com/web/techdoc/dc/reference/cli/nxos/commands/l2/bandwidth__interface.html

Usage Guidelines

The bandwidth command sets an informational parameter to communicate only the current bandwidth to the higher-level protocols; you cannot adjust the actual bandwidth of an interface using this command.

Thank you for your help.

Joseph W. Doherty
Hall of Fame
Hall of Fame

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Posting

Why we configure bandwidth value to a interface ? Is it possible to utilize this value to rate limit ?

As already noted by Mark, setting the bandwidth statement informs other protocols of the amount of logical bandwidth, and whatever it's set to doesn't normally impact the available physical bandwidth.  For example, routing protocols might use the bandwidth setting for metric calculation.  Interfaces will often use it for link loading percentage computations.

I think I recall some of the later IOSs support percentage based policing.  If they do, they might use the bandwidth setting.

If I adjust the bandwidth for a one gig ethernet interface from 1000 to 10, what is the real transit capacity for this interface now?

Again, if you're changing the bandwidth statement, and there are not QoS statements using it, the only difference you might see is on the interface's bandwidth loading stats.  I.e. for the same actual bandwidth usage, it should show a percentage 100 times larger.

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