[181214] in North American Network Operators' Group
Re: Anycast provider for SMTP?
daemon@ATHENA.MIT.EDU (Larry Sheldon)
Thu Jun 18 22:18:21 2015
X-Original-To: nanog@nanog.org
Date: Thu, 18 Jun 2015 21:18:07 -0500
From: Larry Sheldon <larrysheldon@cox.net>
To: nanog@nanog.org
In-Reply-To: <hxjw1q00h1cZc5601xjyp7>
Errors-To: nanog-bounces@nanog.org
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)
