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Date:      Thu, 8 Feb 2001 20:13:33 -0600 (CST)
From:      Chris Dillon <cdillon@wolves.k12.mo.us>
To:        Bill Paul <wpaul@FreeBSD.ORG>
Cc:        <hackers@FreeBSD.ORG>, <net@FreeBSD.ORG>
Subject:   Re: call for testers: port aggregation netgraph module
Message-ID:  <Pine.BSF.4.32.0102081944180.69135-100000@mail.wolves.k12.mo.us>
In-Reply-To: <20010208212509.E8D7D37B6AA@hub.freebsd.org>

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On Thu, 8 Feb 2001, Bill Paul wrote:

> http://www.freebsd.org/~wpaul/FEC/4.x/fec.tar.gz
> http://www.freebsd.org/~wpaul/FEC/5.x/fec.tar.gz
>
> This is a call for testers for a netgraph module that can be used
> to aggregate 2 or 4 ethernet interfaces into a single interface.
> Basically, it lets you do things like the following:

[snip]

> The fec module will work with *any* combination of interfaces, not
> just multiport ethernet cards, however the port failover mechanism
> will not work unless the interface supports ifmedia and is able to
> report the link status. Cards that use the fxp, de, xl, tl, rl,
> sis, dc, wb, ste, sf, vr, ti and sk drivers should work. Yes, that
> means you can aggregate RealTek cards and gigabit ethernet cards
> together.

Awesome!  I've been using channel bonding/port-failover on my NT
servers for at least a couple of years now.  One thing, though,
wouldn't the plural of 'fec' be 'feces'?  :-)

> The channel bonding is done using the Cisco fast etherchannel
> mechanism. The default hashing mechanism uses the MAC address,
> however you can select IP address hashing as well. IPv4 and IPv6
> address *should* work, though I must admit I've been using IPv4
> until now. If someone actually has a Cisco switch that implements
> fast ethetchannel, I'd be interested to know if it works with this
> module. At the moment, my test environment consist of two machines
> with multiport ethernet cards wired up using four crossover
> cables.

Apparently there is another way to do channel bonding with switches
that don't support Cisco's EtherChannel, since I'm doing it with
3COM's (piece of *hit) SuperStackII switches and I don't have
EtherChannel support enabled in Compaq's NT drivers for their Intel
NICs.

I will try this out on -stable at work, but the only switches I have
handy that support EtherChannel are some HP ProCurve 4000Ms.  Is there
any chance that the EtherChannel method would work on something like a
3COM SuperStackII 3300, which doesn't claim to support EtherChannel?

> Each link is checked once every second to see if the link is still
> up. An attempt to send a packet over a dead link will cause the
> packet to be shifted over to the next link in the bundle.

Apparently Compaq's NT driver (actually most likely Intel's, slightly
modified by Compaq) sends out a heartbeat packet from each interface
if there has been no incoming traffic on the interfaces within the
heartbeat period.  I haven't sniffed the heartbeat packet yet to
figure out if it is simply sent to a broadcast address (which it
appears to be, since the switch appears to forward it to all ports),
or if it is sending it from one interface addressed to another
interface, or even to the same interface.

[snip]

> The fec0 pseudo-interface will inherit the MAC address of the first
> real interface to be added to the bundle, and that same MAC address
> will be propagated to all subsequent interfaces that are added.

[snip]

Hmmm... The non-EtherChannel method apparently uses a different MAC
for each interface, since when I have looked at the forwarding tables
of my switches where I have two bonded channels from a server, each
port shows a different MAC address.  Any idea how that would work?
It would be really cool if you could choose either the EtherChannel
method or some other non-EtherChannel method that will work with other
switches, if we can figure out how it works.  :-)


-- Chris Dillon - cdillon@wolves.k12.mo.us - cdillon@inter-linc.net
   FreeBSD: The fastest and most stable server OS on the planet.
   For IA32 and Alpha architectures. IA64, PPC, and ARM under development.
   http://www.freebsd.org




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