Re: Etherchannel or VIPa ? ?


"JW" <janwillem.delange@xxxxxxxxxxxxxxxxx> wrote in message
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"Steve Greatbanks" <steve_greatbanks@xxxxxxxxxxx> schreef in bericht
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"JW" <janwillem.delange@xxxxxxxxxxxxxxxxx> wrote in message
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Hi,
I am trying to find out what provides the best availability and
reliability.

I have two ethernet adapters connected through two different Cisco
(6500) switches.
It looks that Etherchannel requires a connection through 1 switch, or
the (NIB) primary / backup adapter option.
Last option does not provide load balancing.

Virtual Ethernet seems a good alternative, but requires three
ip-adresses in the same subnet.

Any goo ideas or possibilities on AIX 5.3 and Cisco 6500 ?

Something we do is to use a set of stacked Ciscos (3750). You can
etherchannel across
the stack and get redundancy without "wasting" an adapter as a backup
that will never get used.
You need to use the "classic" etherchannel mode (non-LACP) to allow the
etherchannel to
survive a switch failure.
Don't know if you can stack 6500s.



Steve,
Sounds Oké, two adapters really in use and good failover
If this works on 3750 it should be Oké on 6500 also.
With "classic" you mean two equivalent roles for the adapters, and No
primary/secondary I assume?
Rather a sort of creating a link aggregation with twice the bandwidth?
Jan Willem

By "classic" I mean the default ("standard") etherchannel mode which does
not use LACP.
When you make an etherchannel (smitty etherchannel), you don't want the
802.3ad or "round robin" mode. You need to define a channel group on
the switch stack (so you explicitly define which ports constitute the
etherchannel).
As you note, you get the redundancy benefits because your NICs are in
multiple
physical switches, and the stack can survive switch failures, and you get to
use all
of your NICs so you get all of the available bandwidth. You can still use a
backup
adapter in addition to this, but we didn't see the benefit.


.

Relevant Pages

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