nanog mailing list archives

Re: Anycast provider for SMTP?


From: Larry Sheldon <larrysheldon () cox net>
Date: Thu, 18 Jun 2015 21:18:07 -0500

On 6/18/2015 16:40, Jonas Björk wrote:

On Jun 18, 2015, at 11:29 PM, Larry Sheldon <larrysheldon () cox net> wrote:

On 6/18/2015 16:25, Jonas Björk wrote:

Because clients will switch to unicast for renewal. Also clients will stay
with the current server forever, so you might have a bad distribution of
load between the servers. If one server was down everyone will switch to
the other and never go back until forced.

Why wouldn't they go back to the nearest server when it comes back online?

Been awhile, but it seems like they try to "renew" the lease they have, with the server that holds it.

The clients speak unicast with one single ip-helper which address is shared by all the servers.
They can't choose which ever server to talk to.

One of us is confused (and it may well be me) but I thought the ip-helper address was only useful in the initial grope-in-the-dark for a server that is not on the local Ethernet broadcast domain.

Thereafter the negotiations (I thought) are between the client and the responding server and forever after until a failure-to-renew occurred.

--
sed quis custodiet ipsos custodes? (Juvenal)


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