Re: [mpls] MPLS ring protection reconsidered ??

[Kireeti Kompella <[e-mail]>]

Shahram,


On Mar 17, 2015, at 01:14 , Shahram Davari <[e-mail]> wrote:

> Hi Loa
> 
> I support merging these two drafts as I mentioned it on the Mic during last IETF. 

I don’t.

Here’s why (in addition to points that others have mentioned):
1) The two drafts have different views of ring LSPs.  draft-cheng creates LSPs on rings; RMR creates ring LSPs (LSPs that start and end at the same node).
2) draft-cheng is focused on MPLS-TP; RMR is focused on IP/MPLS & MPLS-TE
3) RMR considers the issue of “bypass links”.
4) RMR, in addition to protection, also aims to significantly reduce the configuration of ring LSPs.

Kireeti.

> Regards,
> Shahram
> 
> 
>> On Mar 16, 2015, at 10:23 PM, Loa Andersson <[e-mail]> wrote:
>> 
>> 
>> Folks,
>> 
>> (taking my chair hat off for a while, i.e. this should not be
>> read as a chair directive, just a bit of mumbling that comes out
>> thinking about how to progress documents.)
>> 
>> As far back s the 73rd IETF in Minneapolis John and Adrian made
>> a report on "Requirements for Ring Protectionin MPLS-TP". The
>> conclusions were that we could do topology specific protection
>> solutions if the benefits are big enough.
>> 
>> Such solutions need to meet the same requirements as linear
>> protection and it has to be show that it can't be done by linear
>> protection only.
>> 
>> At that time we did not see that there were things that would not
>> be as readily done by the linear protection being specified at that
>> time.
>> 
>> Today we have to drafts that address ring topologies, one draft-kompella-mpls-rmr addresses Resilient MPLS Rings in an MPLS-TE
>> environment. The other draft-cheng-mpls-tp-shared-ring-protection
>> addresses protection in an MPLS-TP environment.
>> 
>> Both recognizes that ring topologies are very common and that very
>> efficient mechanism for keeping traffic flowing in case of failures
>> are possible to design. Sometime far better than what is the case if
>> the actual ring topologies are view as a linear topology,
>> 
>> The first document (draft-kompella- ) looks primarily on the operations
>> within a single ring and how fast and simple mechanisms for protection
>> can be deployed. A ring topology is a very common deployment scenario.
>> While, the draft-kompella from a solutions point is somewhat orthogonal
>> to draft-cheng, it does also discuss the dynamic control plane for mpls
>> ring, including auto-discovery and signaling. It seems that there are
>> opportunities for co-operation between the two drafts in this area.
>> 
>> The other (draft-cheng- ) looks at what is called MPLS shared ring, i.e.
>> a rather high number can shared the same path around the ring, and all
>> traffic can be protected by a single operation.
>> Another aspect of the shared tunnel is that if part of the ring
>> (typically 2 nodes and one link) are part of more than one ring. It
>> becomes possible to protect against more than one failure.
>> 
>> Maybe it is time to revisit the question and see if we want to adopt
>> working group documents for the two scenarios outlined above.
>> 
>> /Loa
>> -- 
>> 
>> 
>> Loa Andersson                        email: [e-mail]
>> Senior MPLS Expert                          [e-mail]
>> Huawei Technologies (consultant)     phone: [phone]
>> 
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