Eric Hidle on 13 Sep 2004 22:32:02 -0000

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Re: [PLUG] Bonding GRE tunnels

There's a subtle difference between load balancing and trunking. In fact, I
am now having a big discussion on IRC about it :) Load balancing is done
route by route, so once a route is cached, it will always use one pipe or
the other, but never both. Trunking is different in that it uses round-robin
to distribute frames across two interfaces, independent of routing
information. In my case, routing would be static and determined by the
underlying GRE tunnels. The bonding would see the two tunnel interfaces and
round-robin between them.

I cannot bond the two Ethernets together because they don't go to the same
place - they are over two different ISPs. The only thing I have that ends up
at the same place is the GRE tunnel. Basically what I need to do is 802.3ab
at the IP layer instead of the MAC layer. If I did have two connections to
the same ISP, and their router supported 802.3ab, I could theoretically set
up, with their cooperation, MAC-layer bonding between my router and theirs,
and everything would be happy. Unfortunately that is not the case, yet...

----- Original Message ----- 
From: "Mark M. Hoffman" <>
To: <>
Sent: Monday, September 13, 2004 6:25 PM
Subject: Re: [PLUG] Bonding GRE tunnels

> Hi Eric:
> * Eric Hidle <> [2004-09-13 17:53:04 -0400]:
> > Ok, so everyone knows you can bond two Ethernet interfaces if you want
> > bandwidth... here's the bugger - does anyone think it would be possible
> > bond two GRE tunnels between two locations. I have two places each with
> > DSL connections and it would be great to be able to bond the GRE tunnels
> > between them for aggregated bandwidth...
> >
> > Any ideas?
> Heh, I was just reading the Linux Advanced Routing HOWTO (1) the other
day.  Since
> the load-balancing stuff works at the device/interface level, why not do
it the other
> way around: bond the two together and then tunnel over that?
> (1) Just in case you haven't seen it:
> Regards,
> -- 
> Mark M. Hoffman
> Philadelphia Linux Users Group         --
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