PAgP Silent/Non-silent Mode

peanutnoggin

TE,

Tell me if I’m reading this correctly. In the SWITCH foundation learning guide (p. 102), the characteristics of PAgP are Auto, Desirable, On, & “Non-silent”. I am very familiar with the Auto, Desirable, and On modes, but I hadn’t heard of the “Non-silent” option. The explanation is as follows:

“If a switch is connected to a partner that is PAgP-capable, configure the switch interface for non-silent operation. The non-silent keyword is always used with the auto or desirable mode. If you do not specify non-silent with the auto or desirable mode, silent is assumed. The silent setting is for connections to file servers or packet analyzers; this setting enableds PAgP to operate, to attach the interface to a channel group, and to use the interface for transmission”

Is this saying that you configure file servers and packet analyzers for silent mode because they are not going to send any PAgP messages every 30 seconds like the Cisco switch’s do? I guess I’m not sure of what the benefit of the silent/non-silent mode is. Any thoughts? Thanks.

-Peanut

chmorin

I just read that a few days ago. The feature allows you to use PAgP on devices like servers and other non-cisco hardware. The hardware is not capable of telling the switch "Hey, I'm using PAgP too!", so the cisco switch will create the etherchanel by default anyway unless you tell it that the other end is "non-silent".

By default, it will create the etherchannel regardless of the other end agreeing. If you say "non-silent" it will only create it if the other end is PAgP compliant.

The book goes on to say:

If you expect a PAgP-capable switch to be on the far end, you should add the non-silent keyword to the desirable or auto mode... If PAgP isn't heard on an active port, the port remains in the up state, but PAgP reports to the STP that the port is down.

Hopefully this helps you know when you should and should not use the non-silent addition to the command.

peanutnoggin

Thanks Chmorin,

I guess it's one of the "gee-whiz" command options... Just thought I'd get someone else's take on it... Have you (or anyone) used the non-silent in production? Is it any additional benefits to using it? Thanks again.

-Peanut

chmorin

To me it seems like they got it backwards. You should label when things are silent on the other end, not non-silent. But oh well, it still achieves the same goal.

peanutnoggin

My thoughts exactly... That's why I didn't understand the benefit of it