The MPLS WG Archive

[Puneet Agarwal <puneet@pluris.com>]

1) The draft needs to detail the usage of hierarchical tunnel (HT)
especially
in the case of PHP. 

For PHP and HT to work for diffserv/MPLS the Penultimate LSR needs to know
the PHB -> EXP
mapping of the underlying encapsulated tunnels. Moreover, if a LSP is
carrying
multiple LSPs with different PHB-> EXP mapping, the penultimate LSR and even
the egress LSR (in case of no PHP) would need to determine (after Pop), the
type of the underlying LSP.

Another example to illustrate this complexity:
Consider the case when a L-LSP is sent over a prior established E-LSP. the
Penultimate LSR for the E-LSP has no knowledge of tunnels that are
hierarchically going through it. Hence when it does the penultimate POP, it
has no knowledge about the PHB->EXP encoding for the underlying L-LSP.
In order to do this correctly, one would need to maintain additional state
associated with the outer E-LSP in order to do the correct PHB-> EXP map for
the encapsulated L-LSP.

2) pg 21 - In the Pipe Model, when performing multiple push operations, the
LSR may need to be able to encode different PHB->EXP markings for each
pushed
label in the stack

3) pg 36, 3rd paragraph - recognizes --> recognize

4) pg 36, 5th paragraph: when a LSR can only support preconfigured
EXP <--> PHB mapping, if someone wants to set up the per label EXP <--> PHB
mapping, what error should the LSR return? Hopefully this error code is
different than "Diff-Serv Error" to differentiate it from invalid
EXP <--> PHB mapping.

-Puneet