Thanks guys. Much apprecitaed. Shine
----- Original Message ----- From: "Johannes Resch" <[email protected]>
To: "Shine Joseph" <[email protected]> Cc: <[email protected]> Sent: Tuesday, June 23, 2009 2:23 PM Subject: Re: [c-nsp] MPLS QoS On Tue, June 23, 2009 05:12, Shine Joseph wrote:
Hi, Can anyone with SP experience state why would one choose pipe model over short pipe model or vice versa for deploying MPLS QoS?
With full pipe you get some nice benefits like the ability to classify all user traffic only based on MPLS EXP (since traffic will always be transported labelled only), and giving your end customers the option to transport their customer-set DSCP value transparently through your network. (you can fully decouple your core QoS handling from customer-set DSCP values). However, there are also a few issues here: Full pipe model requires ultimate hop popping, which has a performance penalty on many platforms. (e.g., on 7600 with SUP720/RSP720 it forces a recirculation of the traffic on the egress PE, effectively halving the PPS rate of the box). On that platform, supposedly EARL8 will have the HW capabilities of doing a label pop operation plus IP lookup at the same time without recirculation. Also, be sure to test HW platforms you are using well before making this decision. We found quite a few nasty bugs related to UHP on multiple vendors' products in the process, which lead me to think that UHP is not really commonly used (yet). One example - due to a HW bug on 6500/7600 3B/3BXL cards, full pipe mode does not work at all on any 6500/7600 chassis if it is in 3B/3BXL mode (if activated regardless, it leads to wrong imposed EXP values for traffic IP->MPLS). This has been fixed in 3C/3CXL HW. HTH, -jr _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
