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

zhai.hongjun@zte.com.cn zhai.hongjun at zte.com.cn
Thu Jan 12 21:05:29 PST 2012


Hi Tissa£¬

In the diagram you given, assume 4 distribution trees are acturally 
calculated in TRILL campus, i.e., T1 through T4.  T1 and T2 are assigned 
to RB1, T3 and T4 are assigned to RB2.

Even if RB1 can not see  RB2 by hellos, (I think that) RB1 can generate a 
pseudonode LSP, Pseu-LSP-RB1,  to announce the virtual RBridge (RBv) 
nickname and the trees assigned to it, i.e, T1 and T2.  In this pseudonode 
LSP,  RB1 is the only one neighbor (or RB1 and the virtual RBridge RBv are 
the only two neigbors)  of this pseudonode.  After receiving this 
pseudonode LSP,  RBx can  know the path to  pseudonode RBv through RB1 on 
T1 or T2, shown in the following diagram.

                                  RBx
                                     |
                           Trill Campus
               |                                              |
    +----------+                                   +------------+
    |  RB1     |                                  |  RB2       |
    +----------+                                  + ------------+
          \ 
          /  \ 
        /RBv \ 
       ---------
                scheme of T1 or T2

RB1 uses Nickname Sub-TLV and Trees Sub-TLV (instead of the Affinity 
sub-TLV) in Pseu-LSP-RB1, to contains the RBv's nickname and the assigned 
trees T1 and T2.

RB2 also annouce similar informtion in its pseudonode LSP, then RBx can 
know the path to RBv through RB2 on T3 and T4.

                                  RBx
                                     |
                           Trill Campus
               |                                              |
    +----------+                                   +------------+
    |  RB1     |                                  |  RB2       |
    +----------+                                  + ------------+
          \                                                  /
           \                                               /
            \                                            /
              ----------               -----------
                      >   |             |  <  Port channel (LAG)
                           |             |
                    +--------------------+
                   |    CE                    |
                   +---------------------+




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> 
2012-01-13 12:21

ÊÕ¼þÈË
<zhai.hongjun at zte.com.cn>
³­ËÍ
<rbridge at postel.org>, <rbridge-bounces at postel.org>
Ö÷Ìâ
RE: [rbridge] Coordinated Multicast Trees to solve RPF issues on 
active-active edge and more






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 


ÊÕ¼þÈË
<rbridge at postel.org> 
³­ËÍ

Ö÷Ìâ
[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 
  
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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