IPv6 and possible ways of tunneling VOIP over the Global IPv4
Monday, November 2nd, 2009
I have stated looking into deploying Win2008 which made me do a bit of research on Ipv6 tunneling and coexisting it with IPv4.
Voice over IP can survive low bandwidth but has hard time with network latency (a human syllable averages 200ms-300ms) so choosing the best possible IP implementation will effect the transmitted voice quality), this makes AU/NZ VOIP a real interesting challenge.
These seem to be the main network/transport level solution I came across:
ISATAP: uses Dual-stack nodes to automatically tunnel IPv6 packets in IPv4, i.e., ISATAP views the IPv4 network as a link layer for Ipv6.
Teredo: creates IPv6 connectivity by tunneling packets over UDP, Teredo service runs by sing “Teredo servers” and “Teredo relays”. Teredo relays act as IPv6 routers between the Teredo service and the native” IPv6 Internet.
6to4: treats the NAT box as a point to point link layer router into the native Ipv4 network and abstracts the global routing by using the NAT gateway as its Ipv6 termination point.
Tunnel Brokers: uses dedicated servers, called Brokers, to automatically manage tunnel requests coming from the Ipv6 client. Maps isolated IPv6 clients to agree on the routing tables used, allows the client to connect and activate IPv6 connections to other IPv6 by creating a virtual network between the Ipv6/IPv6 dual stack nodes. Dual stack users are nodes that can implement both protocols and uses the v4 implementation for the encapsulation mechanism.
From knowing how Cisco and Junipers are working together my guess will be that dual stack application level proxies (HTTP, SIP) that allows serving clients on both protocols will be the most common implementation in the short term (i.e. ISPs will be able to negotiate optional delivery methods over the available link and allow all types of client to receive the relevant service according to the clients protocol capabilities(blue coat seems to have a lot of research going in this direction)
This also make sense in terms of fighting latency as well since it allows efficient traffic over IPv6 on high bandwidth links (ISP to ISP) and last mile content proxy mechnism for optional clients (Win XP can do IPv6 from SP1).. VOIP will do the same with SIP termination points as the application proxy.