[SR-Users] Kamailio Active / Active HA.

[Ben Langfeld]

On 30 December 2014 at 22:49, Måns Nilsson <mansaxel at besserwisser.org>
wrote:

> Subject: Re: [SR-Users] Kamailio Active / Active HA. Date: Mon, Dec 29,
> 2014 at 11:13:34AM +0000 Quoting Ben Langfeld (ben at langfeld.co.uk):
>
> > Just a word of caution here, there are several SIP stacks which don't
> > handle SRV lookups correctly. I don't mean to discourage you from this,
> but
> > just to be aware of it. For example, Mobicents only understands SRV
> record
> > sets which return domain names. If you return IPs, Mobicents will go
> ahead
> > and look them up as A records and fail.
>
> I would never, ever, put an IP address in the Target field of a SRV
> record. The specification says:
>
>    Target
>         The domain name of the target host.  There MUST be one or more
>         address records for this name, the name MUST NOT be an alias (in
>         the sense of RFC 1034 or RFC 2181).  Implementors are urged, but
>         not required, to return the address record(s) in the Additional
>         Data section.  Unless and until permitted by future standards
>         action, name compression is not to be used for this field.
>
>                 RFC2782, p3
>
> Pretty clear. A host name there should be, resolved to an AAAA/A
> record. Mobicents is actually Doing The Right Thing; even though one could
> claim the Robustness Principle in favour of the more lenient behaviour,
> it is indeed proper to expect to be able to do DNS AAAA/A lookups on
> the Target string.
>

Ah, I was not aware of this. Thanks for pointing it out :)


> Further, it is a syntax violation to put an IPv6 Address in the Target
> field. I made a copy of my zone file and threw in a bogus SRV record. Then
> I gave it to the BIND 10 syntax checker, which most predictably barfed
> on it:
>
> ball-empfang:tmp mansaxel$ /usr/local/bind10-0a1/sbin/named-checkzone
> besserwisser.org bsu
> bsu:35: warning: 2001:470:28:842:201:2eff:fe48:86aa.besserwisser.org: bad
> name (check-names)
> zone besserwisser.org/IN: _knolk._tcp.besserwisser.org/SRV
> '2001:470:28:842:201:2eff:fe48:86aa.besserwisser.org' has no address
> records (A or AAAA)
> zone besserwisser.org/IN: loaded serial 2014122801
> OK
> ball-empfang:tmp mansaxel$ sed -n 35p bsu
> _knolk._tcp 10 SRV 0 0 567 2001:470:28:842:201:2eff:fe48:86aa
>
> So, dont! ;-)
>
> /Måns, who has a population of specialised IP phone devices that most
>         certainly won't do SRV.
> --
> Måns Nilsson     primary/secondary/besserwisser/machina
> MN-1334-RIPE                             +46 705 989668
> LOOK!!  Sullen American teens wearing MADRAS shorts and "Flock of
> Seagulls" HAIRCUTS!
>
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