On Sun, 30 Sep 2007 10:54:34 +0930 Mark Smith <nanog@85d5b20a518b8f6864949bd940457dc124746ddc.nosense.org> wrote:
On Sat, 29 Sep 2007 14:45:23 -1000 Randy Bush <randy@psg.com> wrote:
MPLS as well as the IETF softwires techniques (the MPLS model without using MPLS i.e. tunnel from ingress to egress via automated setup tunnels - gre, l2tp, or native IPv4 or IPv6) can or will shortly be able to be used to tunnel IPv6 over IPv4 or vice versa. softwires in effect treats the non-native core infrastructure as an NBMA layer 2.
The advantage of these techniques verses dual stack is that they push the complexity of dual stack to the network ingress and egress devices.
Dual stack isn't all that complicated, however when you think about running two forwarded protocols, two routing protocols or an integrated one supporting two forwarded protocols, having two forwarding topologies that may not match in the case of dual routing protocols, and having two sets of troubleshooing methods and tools, I think the simplicity of having a single core network forwarding protocol and tunnelling everyting else over it becomes really attractive.
huh? and your tunnels do not have *worse* congruency problems than dual stack? gimme a break.
I do not understand what you mean.
The tunnelled traffic takes the same ingress-to-egress path through the core that it would if the core natively supported the tunnelled payload protocol.
This is the basic BGP/MPLS model, using IPv4, IPv6, GRE or L2TP as the encapsulation, instead of MPLS.
It's also the RFC1772 BGP encapsulation model (section "A.2.3 Encapsulation"), with the difference being the end-node traffic sources and sinks are the ingress and egress peers, rather than an AS worth of them. The model isn't very new at all.
Regards, Mark.
--
"Sheep are slow and tasty, and therefore must remain constantly alert." - Bruce Schneier, "Beyond Fear"
-- "Sheep are slow and tasty, and therefore must remain constantly alert." - Bruce Schneier, "Beyond Fear"