From: Mike Kraus \(mikraus\) (mikraus@cisco.com)
Date: Sat Jul 14 2007 - 10:07:17 ART
Two things I would add.
1)
Having Auto on one side of a link and 100/full on the other is not a
supported configuration. When you set the port speed/duplex, this
disables negotiation. As a result, the side set at Auto doesn't
negotiate the duplex and defaults to 100/half. Obviously the duplex
mismatch will cause problems. (Note: some NIC drivers overcome this,
but in general this is bad practice.) So, only set the port speed to
full duplex if the other side is also hard set to full duplex. This
being the case, I'd only set the port speed/duplex if you are told to do
so. (100/half to Auto should always function correctly).
3)
I see the "channel-protocol" as a safe guard. If you define the
channel-protocol first, it will not let you enable an invalid
negotiation mode. (Try entering "channel-protocol" lacp followed by
"channel-group 1 mode desirable", it should give a channel protocol
mismatch). Aside from that, I haven't seen any application for it
either. Maybe a question like "Ports 23 & 24 in the future will be using
Etherchannel, but you want to ensure that only PAgP is supported once it
is enabled"?
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Capt.Spock
Sent: Saturday, July 14, 2007 6:32 AM
To: Antonio Soares
Cc: ccielab@groupstudy.com
Subject: Re: 3 Questions about the Switching Topic
> I have these 3 questions and i would appreciate your inputs:
>
> 1) When nothing is said about speed/duplex settings, should we
> configure anything ? I usually do not configure anything, everything
> is left as default but i'm unsure if in the lab i will miss points for
this.
I AGREE.
2) When you are told to dynamically negotiate an ISL trunk, should we
narrow
> down the encapsulation mode with "switchport trunk encapsulation isl"
> or leave it in auto ?
I would do leave auto but in real life I would do manual config as
habit.
3) When configuring EtherChannels, in which circumstances should we use
the
> "channel-protocol" command ? I really do not understand the purpose of
> this command. When we configure an EtherChannel, we only have 3
> options: on, pagp or lacp. There is no mechanism to dinamically choose
> either pagp or lacp so i do we need this command ?
I would do only if the req specifies some thing like..MAKE SURE or else
no extra commands.
This is to ensure that the etherchannel group can only run the
etherchannel protocol specified by the channel-protocol command. The
channel-group interface configuration command does not override the
etherchannel protocol command.
This archive was generated by hypermail 2.1.4 : Sat Aug 18 2007 - 08:17:40 ART