[asterisk-bugs] [JIRA] (ASTERISK-18353) SIP registration doesn't use round-robin DNS.

Thu May 2 07:43:38 CDT 2013

    [ https://issues.asterisk.org/jira/browse/ASTERISK-18353?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=206088#comment-206088 ] 

Olle Johansson commented on ASTERISK-18353:
-------------------------------------------

The bug is that there's no new DNS query for EVERY transaction, which there should be. RFC 3263 covering the use of DNS to find the next hop says "The procedures here MUST be done exactly once per transaction". Now, multiple IP entries for one host name is not the recommendation in SIP, since we do have SRV records.

SO there is definitely a bug here. Leif is right, that part of this is a feature request, but not all. For REGISTER to work we need to restart DNS every time we transmit a new REGISTER request. 

> SIP registration doesn't use round-robin DNS.
> ---------------------------------------------
>
>                 Key: ASTERISK-18353
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-18353
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Channels/chan_sip/General
>    Affects Versions: 1.8.5.0
>         Environment: Asterisk 1.8.5.0, Fedora 15
>            Reporter: David Woodhouse
>            Severity: Minor
>
> When there are multiple IP addresses in DNS for a given host, chan_sip only seems to try one of them, repeatedly. It doesn't fall back to the others.
> This is especially noticeable when RFC3484 puts an IPv6 address top in the list but the server doesn't respond on that address (which is a bug, but happens).
> But it's true even for purely Legacy IP setups; if there are multiple servers listed in round-robin, it should try them all before failing.
> But it doesn't. It just tries the *same* host again:
> [Aug 27 10:44:43] NOTICE[16688]: chan_sip.c:12654 sip_reg_timeout:    -- Registration for '01799xxxxxx at c.speechless.aaisp.net.uk' timed out, trying again (Attempt #1782)
> Really destroying SIP dialog '12474a89554cf44a1c33b0cf07c70413@[2001:8b0:10b:1:240:f4ff:fe28:959d]' Method: REGISTER
> Retransmitting #1 (no NAT) to [2001:8b0:0:30:225:90ff:fe05:11ac]:5060:
> (This is for registration; presumably the same problem exists elsewhere.)

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