Hi Udi, folks, Yup. It must discard it, so it won't fallback.
The person who populated the NAPTR records should use the preference field, NOT the order field to indicate preference, if that's want they want to do. (=> Error in Registrant, not in client).
BTW: This is not just in RFC2915, but also in RFCs 3401-3404 (i.e. it isn't just in the obsolete/replaced RFC).
all the best, Lawrence
On 22 Feb 2004, at 12:21 pm, Udi Tirosh (Weintrob) wrote:
Hi all, I have a question regarding NAPTR and RFC 3263 - locating sip servers. Lets assume that my zone file (domain.com) has the following records:
----------------------------------------------------------------------- ------------------
; priority weight port# host name
srv2 1D IN SRV 113 0 5060 h1
srv2 1D IN SRV 114 0 5060 h2
srv3 1D IN SRV 115 0 5060 h3
; order preference protocol SRV name
@ IN NAPTR 1 1 "S" "SIP+D2U" "" srv1
@ IN NAPTR 1 2 "S" "SIP+D2U" "" srv2
@ IN NAPTR 2 1 "S" "SIP+D2T" "" srv3
----------------------------------------------------------------------- ------------------
now lets say I am trying to contact a URI in that domain: sip:[EMAIL PROTECTED]
after querying the DNS with an NAPTR question I will get pointers for three SRV records,
srv1, srv2, and srv3.
in RFC 2915 it is stated that:
The important difference between Order and Preference is that
once a match is found the client MUST NOT consider records with a
different Order but they MAY process records with the same Order
but different Preferences. I.e., Preference is used to give weight
to rules that are considered the same from an authority
standpoint but not from a simple load balancing standpoint.
My question is, should my client discard the 3rd NAPTR record (srv3)? Because if so, it will not be able to fallback to TCP on another server.
I would appreciate any comments, Cheers, Udi Tirosh.
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