The MPLS WG Archive

["Naidu, Venkata" <Venkata.Naidu@Marconi.com>]

Jing & Eric,

-> Although Eric's idea is taken by many people , our experiements shows
-> this is not the truth at least with the situation of our testbed.
-> 
-> In fact we set up a small testbed consisting a Linux based 
-> MPLS engine. In order to focus on difference between forwarding 
-> performance difference between MPLS and IP, we use CBR traffic 
-> with static routing table.
-> 
-> The testbed is consist of  3 hops of MPLS(IP) forwarder 
-> between source and destination. The experiments shows that:
  
  I think your discussion is little deviated. What I understood 
  from Jing's description is that, he didn't apply any form of TE 
  (neither IP-TE nor MPLS-TE) in his network. Jing's measurements 
  are based on straight line topology of 3 nodes, comparing IP and
  MPLS (forwarding) performance only.

  IMHO, in such a small topologies, the amortized performance
  improvements (overall gain of all operations in the worst case)
  may not be significant.

  In such straight line topologies (with out applying any form
  of queuing differentiation or some form of TE in the topology),
  I don't think MPLS out performs IP just because of MPLS 
  fast forwarding nature (may be small amount of improvement).
  Remember that, there is no much difference between IP QoS techniques
  and MPLS QoS techniques (same classes, same queuing methodologies).
  The major difference between IP and MPLS is in TE techniques.

  This discussion reminds me of old draft:
  ftp://ftp.netlab.ohio-state.edu/pub/jain/ietf/draft-bhani-mpls-te-anal-00.
txt
  Where, it is clearly shown that, there is a significant improvement 
  in the throughput of the UDP & TCP flows when MPLS-TE is applied.

  However, can the same performance improvements are achieved using 
  IP-TE methods (at least near to the performance of MPLS-TE) is 
  still an open ended question? 
  
  Some very interesting research has been done to prove the above 
  question. But, "at what cost?", "with how much ease of configuration
  & maintenance?", "with what added benefits?" are still unanswered.

  Finally, I strongly feel that, the performance matrices change a lot
  from small topologies to real-complex topologies. We can't directly
  map the simulation results to real-world topologies. In any case,
  the average/amortized performance measurements & analysis of 
  real-world complex topologies is not an easy task. If there is 
  any such work, I will be very glad to know. 

  Thank You.

--
Venkata.