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Re: 3550 & Etherchannels posted 12/27/2004
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Tim,

Thanks for the good wishes - had a great day with the family! All the best to you, yours and the other highly intelligent, generous and motivated folks who populate this list!

Re PAgP - U got it! I think the critical factor is that the "on" and "off" modes do not send negotiation frames.

Bob Sinclair
CCIE #10427, CCSI 30427, CISSP
www.netmasterclass.net

----- Original Message ----- From: "ccie2be" <ccie2be@xxxxxxxxxx>
To: "Bob Sinclair" <bsin@xxxxxxx>; "Group Study" <ccielab@xxxxxxxxxxxxxx>
Sent: Monday, December 27, 2004 8:28 AM
Subject: Re: 3550 & Etherchannels



Hey Bob,

Merry Christmas. I hope you had a great holiday.

Thanks for getting back to me.

So, basically on a 3550, PagP doesn't do anything automatically and
therefore, if you want an ehterchannel between 2 3550's, both sides

have to be configured.

However, if we're talking about other models Cat's, for example, 6500 or
5000, then PagP will automatically create an etherchannel if only side is
configured correctly.

Is that what you're saying?

Thanks, Tim
----- Original Message ----- From: "Bob Sinclair" <bsin@xxxxxxx>
To: "ccie2be" <ccie2be@xxxxxxxxxx>; "Group Study" <ccielab@xxxxxxxxxxxxxx>
Sent: Monday, December 27, 2004 8:14 AM
Subject: Re: 3550 & Etherchannels



Tim,

Unlike most Cisco switches I have worked with over the years, the default
channel mode on the 3550 is "off", which cannot be set directly, but is
the
absence of other channel mode configurations.

The following PAgP modes should result in a channel:

Desirable-Desirable
Desirable-Auto

Note that "on" is not a PAgP mode, but a static, no-negotiate setting.
Very
unlike the trunking modes!

For real fun, practice with the LACP modes (Active and Passive) and look
into its "hot-standby" feature.

HTH,

Bob Sinclair
CCIE #10427, CCSI 30427, CISSP
www.netmasterclass.net


----- Original Message ----- From: "ccie2be" <ccie2be@xxxxxxxxxx>
To: "Group Study" <ccielab@xxxxxxxxxxxxxx>
Sent: Monday, December 27, 2004 8:01 AM
Subject: 3550 & Etherchannels



> Hey guys, > > I had the impression that PagP could be used to automatically create a
L2
> Etherchannel by just configuring one side of the link,
>
> but I couldn't get it to work.
>
> Here's the topology:
>
> Cat-1 ----- Cat-2
>
> Both 3550's are connected to each other via 3 links
>
> fa0/13 --- fa0/13
> fa0/14 --- fa0/14
> fa0/15 --- fa0/15
>
> and each interface starts out with the default configuration
>
> I used the command on Cat-1, channel-group 1 mode desirable, on all 3
> interfaces.  But, until I also configured Cat-2 the
>
> etherchannel wouldn't come up.
>
> Do both sides of an etherchannel always have to be configured for the
> etherchannel to come up?
>
> If not, how should etherchannel be configured on one side so that the
> other
> side comes up?
>
> If so, what's the point of PagP?
>
> TIA, Tim
>
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