Liaison statement
LS reply on invalid connection address for IPv4 and IPv6

Submission date 2008-05-13
From 3GPP (Susanna Kooistra)
To The IETF (
Purpose For action
Deadline 2008-06-23 Action Taken
Attachments LS on specification of an invalid connection address for IPv4 and IPv6
3GPP TSG CT WG4 Meeting #39	C4-081484
Cape Town, South-Africa, 5th – 9th May 2008

Title:	LS reply on invalid connection address for IPv4 and IPv6
Response to:	
Release:	Release 8 
Work Item:	SIP-I_Nc

Source:	TSG CT WG4

Contact Person:	
Name:	phil hodges
Tel. Number:	+61404069546
E-mail Address:


1. Overall Description:
3GPP TSG CT WG4 are developing a SIP-I application for the Nc interface (Intra
PLMN control plane between MSC Servers) and have a specific optional feature
for deferring the MGW selection. The solution proposes to signal an "invalid"
or "unspecified" connection address when the MGW has not be seized and if the
succeeding node supports the deferred MGW selection procedure it seizes a MGW
and signals the Identity of the MGW back via an SDP attribute.
It is currently proposed to use the unspecified connection address (
however at CT WG4#39 it was questioned that as IETF is mandating the use of
.INVALID for IPv6, could the same solution be used for IPv4 ? Are UA's
currently required to be able to receive this, and therefore it does not
violate any IETF rules for IPv4 connection address usage ? Does IETF offer any
recommendations on this usage ?

2. Actions:
To IETF group.
ACTION: 	CT4 asks IETF whether the .INVALID address may be used to indicate an
unspecified IPv4 connection address and does IETF offer any recommendation in
this respect ?
3. Date of Next CT4 Meetings:
CT4#39bis	23rd – 27th June 2008	Zagreb, CROATIA