SUMMARY: Load balancing across ethernet interfaces [revisted]

From: Craig Faasen (
Date: Tue Mar 31 1998 - 00:15:20 CST

Summary of original question :
Looking for detailed information, particularly references to
documentation, on setting up manual or automatic load balancing across
multiple ethernet interfaces on the same network.

Summary of replies :
Only received one response, suggesting multi-port trunking with specific
reference to Quad FastEthernet adaptors :
> The qfe card from Sun will give you 4 100Mb/s interfaces in one
> slot. And this is the card you need if you want to trunk several
> 100Mb/s ports as one trunk line. You have to check that the switch
> is compatible with this. I know it works with Cisco switches.

Thanks to :
Birger Wathne

Current status :
>From the overall lack of responses and my own unsuccessful quests for
more information, it appears that there is not a lot of documentation
that addresses this rather obvious issue.

Simply to try and get a better feeling for what might and might not be
possible, I stuck a 2nd ethernet interface into a spare SPARCstation,
installed 2.6 and did the obvious :
- set up the 1st interface as normal, called the machine "host1"
- configured the 2nd interface with a unique ethernet address and an IP
  address on the same network, called it "host2"
- from a client, mounted file-systems on "host1" and "host2"
- moved a lot of data to and from the mounted file-systems.

I experienced the kind of behavior described in InfoDoc 15572, viz.
return packets going out through the interface in the cache and not
necessarily the interface they arrived on. Tried to force all return
packets to go out on the interface they came in on simply by disabling
interface groups (/kernel/drv/ip patch 105786-01 is installed), but
snoop still reported return packets going out on the other interface.

Would like to find out more about interface groups ... checked the
Archives and tried to locate information on the Net but once again
crashed and burned (there is a FAQ (228902) at entitled
"How do interface groups work", but I can't get in there and this FAQ is
not on the Sun sites in Germany). Sigh.

-- craig

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