Subject: [OPSAWG] using anycasts of finding configuration servers

From: Juergen Schoenwaelder <[email-masked]>
Date: Sun, 4 Dec 2011 10:56:03 +0100

Hi,

I am starting a new thread just in case this turns into a longer
exchange. Since this document is not specifying a solution, we do not
have to work out all details nor do we have to reach agreement on a
specific solution. But I like to understand what is being proposed and
which text changes should go into the I-D (so far, no concrete text
was suggested). So let me try a few things:

1) The current I-D says:

   Pre-configuration of an IP address is brittle and not recommended.

   It seems that Wes and Christopher argue that once such an IP
   address is an anycast address, this turns into a feature. Is that
   correct? If so, is the goal to relax the existing text into:

   Pre-configuration of an IP address is brittle and not recommended
   unless the IP address is used as an anycast address.

2) It seems once a device talks to an anycast server and identifies
   itself, there needs to be some redirection mechanism. It seems for
   the most likely configuration protocols, that does not exist and
   would have to be defined. Correct or wrong?

3) I am asking (again) whether there is any experience with any
   products using anycasts during the bootstrapping phase. Or is this
   a new idea whose details still need to be worked out?

And like always, concrete text change suggestions would likely make
things easier.

/js

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Juergen Schoenwaelder           Jacobs University Bremen gGmbH
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---

From: Christopher LILJENSTOLPE <[email-masked]>
Date: Mon, 5 Dec 2011 16:21:07 -0800

Greetings,

<hat off, btw>

>   unless the IP address is used as an anycast address.

agreed

>   would have to be defined. Correct or wrong?

not necessarily a re-direct.  If routing is stable for the duration of any configuration event, you can talk to any server.  Since configuration data is basically static, so long as all configuration servers in the anycast cluster have the same data, it shouldn't matter who you pull from.  Worst case, routing shifts during a transaction (which is probably sub-second in nature) you will end up with a TCP reset (or similar), and just re-pull.

>   a new idea whose details still need to be worked out?

I've seen/worked-with tftp servers running anycast.

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