[rbridge] Coordinated Multicast Trees to solve RPF issues on active-active edge and more

Tissa Senevirathne (tsenevir) tsenevir at cisco.com
Thu Jan 12 20:21:26 PST 2012


Hi Hongjun

 

I am not quite clear with the way you are proposing to use assigned nicknames in the pseudonode LSP.

 

Can you please us the diagram below and explain how your proposal will be used. 

 

CE means in the following diagram is an 802.1D device that is attached to RB1 and RB2 through Pt-Pt links and treated as a port channel from CE stand point.

 

                                   RBx

                                     |

                           Trill Campus

               |                                              |

    +----------+                                   +------------+

    |  RB1     |                                  |  RB2       |

    +----------+                                  + ------------+

          \                                                  /

           \                                               /

            \                                            /

              ----------               -----------

                      >   |             |  <  Port channel (LAG)

                           |             |

                    +--------------------+

                   |    CE                    |

                   +---------------------+

 

 

From: zhai.hongjun at zte.com.cn [mailto:zhai.hongjun at zte.com.cn] 
Sent: Thursday, January 12, 2012 7:59 PM
To: Tissa Senevirathne (tsenevir)
Cc: rbridge at postel.org; rbridge-bounces at postel.org
Subject: RE: [rbridge] Coordinated Multicast Trees to solve RPF issues on active-active edge and more

 


Hi Tissa, 

I have read your draft-tissa-trill-cmt-00.txt with great interests.  In this draft, a new TLV, Affinity Sub-TLV, is introduced to give a member RBdige of a virtual RBridge group much flexibity in describing the virtual RBridge nickname and  specifying the path of association to specific distribution tree(S).  However, this new TLV causes some backward compatibilty problems between pre Affinity sub-TLV RBridges and new RBridges. Even if there is only one pre Affinity sub-TLV RBridge in TRILL network,the RPF check for virtual Rbridge will fail on this RBridge.

Is the Affinity Sub-TLV necessary for a member RBridge to announce the virtual Rbridge nickname and  the specific distribution trees? Maybe it is not. 

In a given vritual group, each  member Rbridge can advertise a specific pseudonode-LSP to annouce the virtual RBridge nickname and the trees assigned to it.The nickname and the assigned trees are contained in  the given Nickname Sub-TLV and Trees Sub-TLV in RFC6326. This pseudonode-LSP represents a special virtual link, on which there is only one RBridge, i.e.,  the RBridge advertising this LSP.  Only if different member Rbridge is assigned different tree(s), RPF check information for the virtual Rbrigde in different trees can be correctly calculated on all the Rbridges in TRILL network, then the member RBridge can safely use the virtual Rbridge nickname to do the necessary TRILL-encapsultion on  received native frames. 

Therefore, backward compatibilty problems, caused by Affinity sub-TLV, is removed, while the similar flexibilty of Affinity sub-TLV remains. 


Thanks,
Zhai Hongjun
""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
Protocol Development Dept.VI, Central R&D Institute, ZTE Corporation
No. 68, Zijinghua Road, Yuhuatai District, Nanjing, P.R.China, 210012

Zhai Hongjun

Tel: +86-25-52877345
Email: zhai.hongjun at zte.com.cn
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""





"Tissa Senevirathne (tsenevir)" <tsenevir at cisco.com> 
·¢¼þÈË:  rbridge-bounces at postel.org 

2012-01-06 10:11 

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<rbridge at postel.org> 

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[rbridge] Coordinated Multicast Trees to solve RPF issues on        active-active edge and more

 

		




Dear All 
  
We have published draft-tissa-trill-cmt-00.txt, in this document we present a flexible framework to associate child RBridges to different parent RBRidges for RPF purpose. 
  
Active-active forwarding at the TRILL edge is a very important feature. Representation of the active-active sub system with a single virtual RBRidge is a common practice to achieve load balancing and to avoid MAC flip flop. However, use of virtual RBridge lead to RPF failures. In this document we provide a solution to address the RPF failures. Please review and share comments. 
  
ID can be found in URL: http://www.ietf.org/id/draft-tissa-trill-cmt-00.txt <http://www.ietf.org/id/draft-tissa-trill-cmt-00.txt>  
  
Summary: 
  
Filename:   draft-tissa-trill-cmt 
Revision:   00 
Title:            Coordinated Multicast Trees (CMT)for TRILL 
Creation date:    2012-01-05 
WG ID:            Individual Submission 
Number of pages: 14 
  
Abstract: 
   TRILL facilitates loop free connectivity to non TRILL legacy 
   networks via choice of an Appointed Forwarder for set of VLANs. 
   Appointed Forwarder provides VLAN level load sharing with active- 
   standby model. Mission critical operations such as High Performance 
   Data Centers require active-active load sharing model. Active-Active 
   load sharing model can be accomplished by representing any given non 
   TRILL legacy network with a single virtual RBridge. Virtual 
   representation of the non-TRILL legacy network with a single RBridge 
   poses serious challenges in multi-destination RPF calculations. This 
   document presents the required enhancements to build Coordinated 
   Multicast Trees (CMT) within the TRILL campus. CMT provides 
   flexibility to RBridges to select desired path of association to a 
   given distribution tree. 
  
  
Thanks 
Tissa_______________________________________________
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