SIP & IPv6Dual stack issues

SIP Forum Conference call 12.12.12

oej@edvina.net

onsdag 12 december 12

Agenda

• Locating SIP servers in a dual stack world

• Happy Eyeballs and SIP

• UA media address familiy capability

onsdag 12 december 12

Living in a dual stack world

• RFC 3261 supports either IP4 OR IPv6

• We need to adopt to a dual stack world in order to enable IPv6 migration

• RFC 6157 attempts to handle this, but focuses on media

• ICE supports dual stack media negotiation (with the IPv6 priority addition)

Let’s separate SIP and media sessions (RTP/MSRP/T.38)

onsdag 12 december 12

Locating SIP servers RFC 3263

• Clearly says that a SIP device needs to look up IPv4 or IPv6

• We need to replace ”or” with ”and” and apply happy eyeballs to find the next hop. 64 times T1 for failover will NOT be accepted by users

onsdag 12 december 12

I see two issues

• Indicating preference of address family in DNS SRV records

• Setting up a connection to a dual stack server from a dual stack client

• HAPPY EYEBALLS FOR SIP!

• Affects STCP, TCP and UDP transports

onsdag 12 december 12

Locating a SIP server

• NAPTR doesn’t bother with address family

• SRV records point to host names

• Hosts can be single stack IPv4, single stack IPv6 or dual stack.

• NAPTR can be used to indicate preference of transport. SRV can be used to indicate preference of address family.

SIP

onsdag 12 december 12

The IPv6 preferred chain ;; Priority Weight Port Target IN SRV 10 3 5060 server1.sipguru.no. IN SRV 10 1 5060 server2.sipguru.no. IN SRV 20 1 5060 server3.sipguru.no. IN SRV 20 2 5060 server4.sipguru.no.

_sip._udp.sipguru.no

Priority 10 Priority 20

Server1 75% Server2 25% Server3 33% Server4 67%

AAAA AAAA

A A

AAAA AAAA

No IPv4 records!

onsdag 12 december 12

SIP & Happy eyeballs

onsdag 12 december 12

Happy SIP UAs

• Two network paths to the same service from the same device

IPv4

IPv6

IPv4

IPv6

onsdag 12 december 12

Oh no.

• If the first selected path doesn’t work, what’s the failover time?

• This will affect SIP Trunking (SIPconnect)

IPv4

IPv6

IPv4

IPv6

onsdag 12 december 12

Http Solution

• Happy Eyeballs

• RFC 6555 by Dan Wing

• http://ipv6friday.org/blog/2012/04/happyeyeballs/

Needs to be applied to SIP.

onsdag 12 december 12

UA capabilityDiscovering support for IPv6 and/or IPv4

onsdag 12 december 12

UA IPv6 capability

• In some cases, a SIP Server needs to know if a UA is single stack IPv4, single stack IPv6 or dual stack

• Signalling address family is not proof enough. A dual stack SIP client may decide to send over IPv4 - which doesn’t reveal the IPv6 capability

• This applies to server-based NAT traversal support

onsdag 12 december 12

Hosted RTP proxys

• The proxy receives signalling with IPv6

• Checks all the contacts associated with an AOR

• How does it detect dual stack clients?

• What does it base a decision for adding an IPv4-IPv6-rtpproxy on?

• Either dual registrations or a contact capability indication.

onsdag 12 december 12

SIP Outbound

• Can be used

• Two registers with REG-ID over IPv4 and two with the same REG-ID over IPv6 or two registrations with dual contacts

• Four flows to maintain

• Not very practical

• Lack of Outbound implementations

• Not a short-term fix with a simple upgrade path for firmware

onsdag 12 december 12

The short term fix

• A way to indicate UA media capability for various address families in the contact

• This way, server can make policy decisions on media NAT support

onsdag 12 december 12

Suggested priority

• Happy eyeballs-fixes for SIP - SIP in a dual stack network

• Add dual stack indication in Contact

• Make it possible for SIP Forum members to add IPv6 in dual stack mode without adding support requests...

onsdag 12 december 12

SIPit 30• Raleigh-Durham, NC, USA

• February 18-22

• Sponsor: Cisco

• Will include IPv6 testing!

• Online tests will also be available latest in Jan 2013

http://www.sipit.net

onsdag 12 december 12

STAY CONNECTED.Add IPv6 to your unified communications platform today.

facebook.com/sipv6 edvina.net/sipv6 twitter.com/sipv6Join us here:

Development discussion: sip-implementors mailing list

Vendor tests at SIPit events:www.sipit.net

onsdag 12 december 12

Final message:No, WebRTC will not solve all these issues.

;-)

onsdag 12 december 12