On 30 December 2014 at 22:49, Måns Nilsson <mansa...@besserwisser.org> wrote:
> Subject: Re: [SR-Users] Kamailio Active / Active HA. Date: Mon, Dec 29, > 2014 at 11:13:34AM +0000 Quoting Ben Langfeld (b...@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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