[nsp] Etherchannel and intermediate switches

[Matyas Szilard]

Hi!

It could be done with restrictions. If you use dynamic channel configuration
with PAGP and  use Cisco switches for A and Z. I think it can't work because
PAGP use dest. multicast  MAC that cannot flood  by cisco switches, but sent
to the supervisor. Thus, switch A and Z absorb PAGP. I think if you use  not
cisco switches for A and Z the dinamic channel configuration works. If you
use static channel configuration the A and Z switches can be cisco. There
are other restrictions such as if you make a link between switch A and Z the
MAC addresses are confused. If you dont't use link between switch A and Z
the configuration works, but there is a problem. The failover mechanism
cannot work. Suppose that link between Switch C and Switch Z go down.
Switch B can't realize that one of his channel link not operational, because
there is link between Switch B and Switch F. Switch B forward frames to
Switch Z in the future too and that frames what used that link are lost, and
broadcast frames(for example: arp req.) that use that link too. I think this
configuration is not a good choice!

szicsu

----- Original Message ----- 
From: "Sam Stickland" <sam_ml at spacething.org>
To: "Cisco Nsp" <cisco-nsp at puck.nether.net>
Sent: Tuesday, September 09, 2003 5:28 PM
Subject: [nsp] Etherchannel and intermediate switches


> Hi,
>
> Does Fast Etherchannel work if there are intermediate switches in the way,
> if each channel is guaranteed a separate path?
>
> e.g. Switches A and Z are joined by two channels to create a 200Mbit/s
link.
>
>
>      +------- Switch B -------+
>      |                        |
> Switch A                 Switch Z
>      |                        |
>      +------- Switch C -------+
>
> Are the MAC addresses of B and C going to confuse the port aggregation
> protocol?
>
> Sam
>
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