[reSIProcate] DNS not returning entries after 408?

[Scott Godin]

Before the recent changes, that way I understood it the blacklisting was
supposed to work as follows:

1.        Only blacklist an entry if there other DNS entries to try.

2.       If we have ended up blacklisting all entries from a particular
lookup, then un-blacklist them all and let the next request start the
cycle again.

Scott

 

From: resiprocate-devel-bounces at list.resiprocate.org
[mailto:resiprocate-devel-bounces at list.resiprocate.org] On Behalf Of
Byron Campen
Sent: Thursday, December 07, 2006 2:01 PM
To: Jeremy Geras
Cc: resiprocate-devel at list.resiprocate.org
Subject: Re: [reSIProcate] DNS not returning entries after 408?

 

          This is happening because the stack is blacklisting the tuple
that your server was running on, because it didn't respond. This
blacklist (currently) lasts 32s. I was thinking about making this
duration configurable. Does anyone want to have a discussion about
whether blacklisting on a UDP timeout is something we want to be doing?
It seems to me that we might need to have a concept of "greylisting",
where greylisted tuples will only be used if they are all that remains
to be tried. (This is opposed to a blacklisted tuple, which we should
never try, since chances are we have been explicitly told, with a 503,
to leave the tuple alone for a while.) Any thoughts? (anyone?)

 

Best regards,

Byron Campen

	Hi,

	 

	I'm using the latest code from SVN (updated today), and I've
encountered an issue with DNS in the following case:

	 

	Client                                          Registrar

	      REGISTER (due to user login)------------->

	      <---------------------------------- 200 OK

	 

	(at this point the Registrar becomes unavailable - its IP is
still reachable, but nothing is listening on UDP port 5060)

	 

	      re-REGISTER (due to Expires timer)------->

	 

	(~ 30 seconds go by and then I get a 408 from DUM)

	(client sits idle for ~ 30 seconds more)

	 

	      REGISTER -------------------------------->

	 

	(Get a 503 Service Unavailable immediately from DUM)

	(sit idle for any amount of time)

	 

	      REGISTER -------------------------------->

	      <---------------------------------- 200 OK

	 

	 

	My client is set up to use only UDP as a transport.  I'm using
DUM.  I've looked at the logs, and it seems the reason I'm getting the
503 is that there aren't any DNS entries for my registrar: "Ran out of
dns entries for 192.168.1.172. Send 503".  But this doesn't make sense,
as there definitely should be entries (and since I can register if I try
once again after I get the 503).

	 

	If I go back to an older revision (6609 which is from back in
September), I don't have this issue - i.e. I don't get the 503, my last
REGISTER actually goes out on the wire and I get my expected 200 OK.

	 

	Any thoughts?

	 

	Thanks,

	 - Jeremy -

	 

	 

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