[rbridge] Re: IP and MPLS TTL

[Loa Andersson]

this one too

/Loa

Loa Andersson wrote:

> All,
> 
> on the TTL discussion - and I'm not sure if I want to
> decrement the TTL or not yet - there is one mpls aspect that
> needs to be considered.
> 
> On any given link in a MPLS enabled IP network ther might be
> a mix of "pure" IP-packets and packets encapsulated with a mpls
> shim header. Now, if there are any mpls shim header, and we want
> to decremetn the TLL the rbridge needs to understand to decrement
> the TTL in the shime header, but not in the IP header.
> 
> If the rbridge is the pen ultimate mpls node it should "pop" the
> mpls shim header and re-write the IP TLL based on a set of rules
> (RFC3443) - butif we go down this route the rbridge becomes very
> close to an LSR.
> 
> /Loa

-- 

Loa Andersson

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