Re: [rbridge] Call for draft-tissa-trill-cmt-00 to WG draft

[Janardhanan Pathangi Narasimhan <[e-mail]>]

Hi Zhai,

I think the other point in the pN draft is
The requirement in the PN draft is that we should form a tree with the PN node as the root of the tree. In case we have many LAN links, for e.g. 10, than we would need 10 trees where each tree has the corresponding PN as the root of the tree.
  A similar approach was one of the options considered earlier, but since this would not sale in terms of number of trees, it was felt that the requirement that the PN be the root of the tree would not be possible.

Thanks
Jana

The main difference between PN draft and CMT draft as follows:
1) In PN draft, a member RBridge employs pseudo-LSP to carry pseudo-nickname and members of a virtual RBridge group,
2) While in CMT draft, Affinity TLV is introduced to carry pseudo-nickname and the wanted DTrees by a member RBridge.

> 1) In figure 2 of the CMT draft, the nodes CE1, CE2 etc. treat their links to RB1,
> RB2… RBk as a LAG. Hence if RB1 sends a TRILL hello frame on this link towards CE1,
> this will not be received by any of the other RBridges RB2, .. RB4. Hence the concept
> of AF will not be applicable in this scenario

In PN draft, TRILL hello is mainly used to find member RBridge and to negotiate the pseudo-nickname of a virtual
RBridge group. For a virtual RBridge group, if its member RBridges and pseudo-nickname are configured statically
by a network administrator, TRILL hellos are not requisite in PN draft. Therefore, the idea proposed in PN draft,
i.e., giving a pseudo-nickname to an RBriges Group and using pseudo-LSP to carry information of this RBridge group,
is also applicable in the CMT scenario (given in figure 2 of CMT draft).

Furthermore, using pseudo-LSP, instead of a new TLV, can avoid the backward compatibility issue.


> 2) In the PN draft, only the AF will forward all traffic into and out of this network,
> and this is because it is regular Ethernet link. But in the CMT draft the links are
> all LAGs, and hence the traffic (for e.g. broadcast from CE1) is sent to only one of
> the RB1 and not to all of them.

Although the PN draft discusses the issues of pseudo-nickname mainly based on Ethernet link, the idea of pseudo-nickname
and employing pseudo-LSP to carry RB Group info is also applicable in other scenario, such as LAGs and multi-homing.
Whether using one member RB or all member RBs to forward traffic for an end system, it depends on in which scenario the
pseudo-nickname is used, but not the different ways to implement the pseudo-nickname function between PN draft and CMT draft.


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: [phone]
Email: [e-mail]<mailto:[e-mail]>
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""



Janardhanan Pathangi Narasimhan <[e-mail]<mailto:[e-mail]>>

2012-03-28 00:09

收件人

"[e-mail]<mailto:[e-mail]>" <[e-mail]<mailto:[e-mail]>>, "Tissa Senevirathne (tsenevir)" <[e-mail]<mailto:[e-mail]>>

抄送

Donald Eastlake <[e-mail]<mailto:[e-mail]>>, "[e-mail]<mailto:[e-mail]>" <[e-mail]<mailto:[e-mail]>>, "[e-mail]<mailto:[e-mail]>" <[e-mail]<mailto:[e-mail]>>, "[e-mail]<mailto:[e-mail]>" <[e-mail]<mailto:[e-mail]>>

主题

RE: [rbridge] Call for draft-tissa-trill-cmt-00 to WG draft







Hi Zhai,

Few points:

1) In figure 2 of the CMT draft, the nodes CE1, CE2 etc. treat their links to RB1, RB2… RBk as a LAG. Hence if RB1 sends a TRILL hello frame on this link towards CE1, this will not be received by any of the other RBridges RB2, .. RB4. Hence the concept of AF will not be applicable in this scenario

2)  In the PN draft, only the AF will forward all traffic into and out of this network, and this is because it is regular Ethernet link. But in the CMT draft the links are all LAGs, and hence the traffic (for e.g. broadcast from CE1) is sent to only one of the RB1 and not to all of them.

  So I think the problem space that these two drafts are discussing are different, and the Pseudo Node draft will not be applicable to the LAG active-active load balancing scenarios described in the CMT draft.

Thanks
Jana


From: [e-mail]<mailto:[e-mail]> [mailto:[e-mail]] On Behalf Of [e-mail]<mailto:[e-mail]>
Sent: Tuesday, March 27, 2012 4:49 PM
To: Tissa Senevirathne (tsenevir)
Cc: Donald Eastlake; [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>
Subject: Re: [rbridge] Call for draft-tissa-trill-cmt-00 to WG draft


Hi Tissa

In your CMT draft, if one old RBridge is momitored not supporting affinitive-TLV, the CMT function will be disbale in all the TRILL campus. In my mind, that's your discussion for backward compatibility in CMT. So CMT can not work until all the RBridges support affinitive-TLV.

However, in the PN draft, there is no such backward compatibiltiy. PN draft employs pseudo-LSP to announce the pseudo-nickname and members of a virtual RBridge. If the pseudo-nickname and the members are configured statically by network administors, no hello PDUs are necessary between the members of a virtual RB group. So the pseudo-LSP method given in PN draft can also work for the scenario described in your CMT draft.


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: [phone]
Email: [e-mail]<mailto:[e-mail]>
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""

"Tissa Senevirathne (tsenevir)" <[e-mail]<mailto:[e-mail]>>
发件人:  [e-mail]<mailto:[e-mail]>

2012-03-27 18:12


收件人

<[e-mail]<mailto:[e-mail]>>, "Donald Eastlake" <[e-mail]<mailto:[e-mail]>>

抄送

[e-mail]<mailto:[e-mail]>, [e-mail]<mailto:[e-mail]>

主题

Re: [rbridge] Call for draft-tissa-trill-cmt-00 to WG draft











Hi Hu

CMT draft discuss about backward compatibility  and your assessment of RPF failure when older RBridges present is incorrect.

Additionally I am not clear PN draft can be utilized for the scenario described in the CMT. Per the discussion we have in Taipie, most Data Centers and Enterprise have multi home devices connected to the TRILL edge. They will not let LAN Hello to pass through them because of the LAG bundling at the edge. Please refer to the reference topology in the draft. Hence CMT draft address very crucial deployment scenario.

Thanks
Tissa

From: [e-mail]<mailto:[e-mail]> [mailto:[e-mail]] On Behalf Of [e-mail]<mailto:[e-mail]>
Sent: Monday, March 26, 2012 9:41 PM
To: Donald Eastlake
Cc: [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>
Subject: Re: [rbridge] Call for draft-tissa-trill-cmt-00 to WG draft


Hi,all

We have discussed that there is back compatibility issue for CMT. Only if all the member RBridge of a virtual group support Affinity sub-tlv, the CMT can work correctly. If one of the member does't announce the virtual RBridge nickname and the Affinity sub-tlv, there may exist RPC check failure for the virtual RBridge. The issue that CMT try to solve is not an essential and key issue for trill, and CMT should be a optional solution. Some RBridges may not implement the feature. I wonder whether the CMT will does work actually because of the back compatibility issue.

There is another solution (pseudonode nickname) solves the same issue. I suggest we should do further discussion with CMT and compare with the two solutions.

Thanks
Donald Eastlake <[e-mail]<mailto:[e-mail]>>
发件人:  [e-mail]<mailto:[e-mail]>

2012-03-27 06:38




收件人

[e-mail]<mailto:[e-mail]>

抄送

主题

[rbridge] Call for draft-tissa-trill-cmt-00 to WG draft














During the TRILL session today, there was a consensus of those in the
room to make draft-tissa-trill-cmt-00.txt a TRILL WG draft. This is a
call on the WG mailing list to confirm that consensus. If you wish to
respond, please do so by April 10th.

Thanks,
Donald
=============================
Donald E. Eastlake 3rd   [phone] (cell)
155 Beaver Street, Milford, MA 01757 USA
[e-mail]<mailto:[e-mail]>

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