The MPLS WG Archive

[suchauhan@hss.hns.com]

welcome!
     Pls see answers below. Hope it helps

ciao
sumit




"Mayank Kumar" <mkumar@aplion.stpn.soft.net> on 06/28/2002 02:08:45 PM

Please respond to mkumar@aplion.stpn.soft.net

To:   mpls@UU.NET
cc:    (bcc: Sumit Chauhan/HSS)

Subject:  Mayank (New member)




hi

i am new to this mailing list and a newbie to the MPLS standard as well.
I have read all the relevant rfc's related to MPLS.I have three questions to
the group:-

1:why is a shim header called so??? I mean , what does shim stand for???
Ans. dunno....I guess shim means thin!

2:on a frame based LSR , there can be two atm interfaces. While switcing
between these two atm interfaces on a frame based LSR, is segmentation and
reassembly performed??
Ans. Segmentations and reassembly essentially should be carried out at the
ingress and destination respectively to avoid overhead. Should use PMTU
protocol.

3:I want to setup a LSP for a certain destination using hop-by-hop routed
path. Can anybody describe the complete set of procedcures for doing this...
Ans. Hmmmmm its hard to give the exact set of evets/configurations here but
lemme try to give you a top level view

Step 1 . Let IGP stabilize on all participating LSRs after the network comes up

Step 2. Use the unicast rechability information given to you by IGP to setup
LSPs between LSRs using DoD or Unsolicited mechanisms

Step 3. The ingress LSRs should start classifying packets based on the FEC
information that has any linked LSPs with it.

Step 4. Packets coming in with the correct FEC match are used for searching the
ILM table and forwarded to the intermediate LSRs which search their FTN and
forward the packet using appropriate labels (ATM, FR, Shim etc)

Step 5. The egress LSR (penultimate in case of PHP support) shall strip the
packet MPLS header and forward the native data (IP) packet.

thanks
and regds
Mayank