Subject: [AAA-WG]: Load Balancing

From: Patrice Calhoun <[email-masked]>
Date: Fri, 9 Feb 2001 08:48:27 -0800 (PST)

All,

One of the resolutions at the interim meeting was to use pearson's hash for
load balancing purposes:

	3. The base spec will include text on load balancing across multiple 
	   proxies, and will document Pearson's hash, and use the NAI as the 
	   seed. The hash algorithm can be found in draft-ietf-dhc-loadb-03.txt.

I have been thinking about this alot more, and even tried to put this in the
I-D to see what would fall out, and I am not sure how it would be used. Unlike
DHCP, Diameter nodes do some capabilities exchange, so a client knows whether
a particular request should be forwarded to a next hop or not, based on its
supported extensions.

The hash, as I understand it, would allow a node to hash the NAI and use the
result to identify the next hop. However, doing this will now require that a
separate hash table exist for server+extension. So all servers with the NASREQ
extension would be in one hash, and the same servers MAY also be present in
the Accounting and Mobile IP hash table.

This seems unnecessarily complex, but I wanted to find out from the WG what
people think. Does the above complexity justify a good load balancing
algorithm? Is this something that we really want to support (or recommend) in
the Diameter protocol?

Thanks,

PatC

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From: Barney Wolff <[email-masked]>
Date: Fri, 9 Feb 2001 21:35:11 -0500

Much as I sympathize with the desire to have a particular user's
requests always hit the same server, I believe that's an internal
matter for the organization running the server farm.  If I had to
do that, I'd put a private proxy in front of the farm and then
the hash algorithm is nobody's business but mine.

In other words, I think we're succumbing to the Second System Effect
here, perhaps better known these days as Feeping Creaturism.

Barney