Internet DRAFT - draft-sboyapati-mpls-rsvp-label-reusage

draft-sboyapati-mpls-rsvp-label-reusage



Network Working Group                                 Suresh Boyapati
Internet Draft                                        Juniper Networks
Intended Status: Experimental                       

                                                     July 1, 2017

     
	 
	 Reusage MPLS RSVP Labels during MBB 
      draft-sboyapati-mpls-rsvp-label-reusage-00.txt                    



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Abstract

MPLS is the heart and soul of the service provider network. 
MPLS can carry any data payload which
gives the flexibility to the service provider to provision 
new service with any expense.
In a scaled MPLS RSVP router during MBB/Global repair, router needs to program large number of labels into PFE. 
This operation results in lot of label re-computation and label programming. 
This draft is proposing a solution to label reusage 



Table of Contents

1. Introduction......................................................3
2. MPLS LSP Problem Statement........................................4
3. How MPLS LSP works ...............................................4
3.1 Selection on MPLS LSP for Voice,Video networks 
    based on Loss and delay Parameters...............................
4.1. Normative References............................................5



1.Introduction

MPLS is the heart and soul of the service provider network. 
MPLS can carry any data payload which gives the flexibility 
to the service provider to provision new service with any expense.
As loss and delay sensitive applications such as Voice and 
Video are running on MPLS network, they may suffer delays 
in packet transmission and delivery. 
So Voice and Video traffic on MPLS network needs low loss and
 delay LSP's to transfer Voice and Video packets.
This draft is proposing a solution to selection of Low loss and 
latency LSP's for Voice and Video applications 
using MPLS Loss and Delay measurement parameters.

   
The benefit of this technology results in delivery voice and 
video packets with best possible lsp i.e. LSP's with less loss and delay. 


2. Problem Statement

In the below topology 

10 20 30 40 50 3
A------B-------C--------D-------E-------F--------G
\ /
\ / 
 H

During MBB/Global Repair, the following sequence of events happen with existing Implementation:

1. A will send PATH message requesting label with new lsp-id.
2. Path message will be processed hop-by-hop by all routers in the ERO path. 
3. RESV with New Label will be sent hop-by-hop to the upstream. 
a. Labels before the MBB 10,20,30,40,50,3.
b. Labels after the MBB 11,22,33,44,55,3
c. It is important to note that labels changes before and after the MBB.
4. Routers will program new label in PFEs and switches the LSP to new Label.

Observations with existing implementation : 
1. During MBB every router in ERO path, need to maintain two PSB states with two different labels.
2. During MBB event every router will need to reprogram the label and switch to new Label.
3. After expiration of user defined timer/default timers, old label will be deleted.
4. In a highly scaled MPLS LSP router, this process is very expensive and CPU intensive . 

Proposed Solution:

1. During MBB event, Router A will send PATH message to the Down Stream router with new lsp-id and 
same tunnel-id & Extended tunnel-ID.
2. This PATH message will be processed hop-by-hop by all routers in the ERO PATH.
3. Down Stream router will provide the label based on below conditions:
a. If Tunnel-id & Extended tunnel-ID in the incoming PATH message is part of existing PSB/RSB 
then provide the same existing in used Label.
b. If Tunnel-id & Extended tunnel-ID in the incoming PATH message is not part existing PSB/RSB 
then provide a new Label from available label base.
4. After expiration of configured/user defined timers, depending on 3a or 3b (above) , 
router will either delete the old instance of lsp-id or delete combination of old instance lsp-id & its associated label.

Example 1 with proposed solution (MBB to the same ERO PATH) : 

10 20 30 40 50 3
A------B-------C--------D-------E-------F--------G
\ /
\ / 
 H

In the above topology , 
1. LSP is signaled from A to G. (A---B---C---D----E---F---G.)
2. Due to Auto BW adjustment MBB will take place and selects PATH A---B---C---D----E---F---G.
3. Router A will send a PATH message to Router G, with same tunnel-id and new lsp-id and PATH message 
will be processed in hop-by-hop by every router in the path .
4. Every Router will verify their PSB/RSB for the matching tunnel-id 
5. If tunnel-id & Extended tunnel-ID matches with existing PSB/RSB, then send the same Label 
which is already in use for existing tunnel-id & Extended tunnel-ID combination i.e. label used for psb1. 
6. In the above topology example labels computed for new instance of lsp-id will same as labels used in old lsp-id i.e. 10,20,30,40,50. 
a. Labels before the MBB 10,20,30,40,50,3.
b. Labels after the MBB 10,20,30,40,50,3.
c. It is important to note that labels DO NOT change before and after the MBB.
7. By signalling of same label to Up Stream router, no RE to PFE communication is required regarding label Change. 


Example 2 with proposed solution (MBB to the different ERO PATH than the original ERO) : 

10 20 30 40 50 3
A------B-------C--------D-------E-------F--------G
\ /
60 \ / 40
H

In the above topology , 
1. LSP is signaled from A to G. (A---B---C---D----E---F---G.)
2. Due to Auto BW adjustment MBB will take place and selects PATH A---B---C----H----E---F----G.
3. Router A will send a PATH message to Router G, with same tunnel-id and new lsp-id and PATH message 
will be processed in hop-by-hop by every router.
4. Every Router will verify their PSB/RSB for the matching tunnel-id & Extended tunnel-ID
5. If tunnel-id & Extended tunnel-ID matches with existing PSB/RSB, then send the same Label to the Up Stream Router. 
6. In the above topology example Router E PATH message was received from Router H. When router E compares PSB/RSB 
it has a matching existing session with label 40 sent upstream to Router D. 
7. Router E will use the same label (40) and send it to new Up Stream Router H.
8. On Router H, when tunnel-id & Extended tunnel-ID was compared in PSB/RSB, there is no existing label match, 
hence Router H will signal a new label 60 to Router C.
9. By this signalling of same label to Up Stream router, no RE to PFE communication is required regarding label Change.

 
References:

4.1. Normative References

[RFC2205] Resource ReSerVation Protocol (RSVP)
[RFC3209] RSVP-TE: Extensions to RSVP for LSP Tunnels



Author Address

Suresh Boyapati
Juniper Networks 
Sunnyvale,CA
USA
Email: sureshkb@juniper.net