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Re: [CCAMP] MELGs - Q&A

Fatai Zhang <zhangfatai@huawei.com> Thu, 21 March 2013 03:37 UTC

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From: Fatai Zhang <zhangfatai@huawei.com>
To: Vishnu Pavan Beeram <vishnupavan@gmail.com>, "ccamp@ietf.org" <ccamp@ietf.org>
Thread-Topic: [CCAMP] MELGs - Q&A
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Date: Thu, 21 Mar 2013 03:37:30 +0000
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Subject: Re: [CCAMP] MELGs - Q&A
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Hi Pavan,


4. How is MELG different from SRLG?

Each construct addresses a separate problem. SRLGs are used to advertise "fate-sharing" information. MELGs are used to advertise "mutual exclusivity" information.

It is possible for TE-links that have a common SRLG to be instantiated/used at the same time. It is not possible for TE-links that have a common MELG to be instantiated/used at the same time - only one of them can be used at any given point of time

[Fatai] I don't understand your definition of MELG(ie., MELGs are used to advertise "mutual exclusivity" information).  If we name it as XXLG, we can define XXLG similarly in your style: XXLGs are used to advertise "XX" informaiton.  My real question is: Why is there "mutual exclusivity"?   What is the essence of "mutual exclusivity"?

In additon, what you said in the second sentence about "possible" vs "not possible" is a kind of policy, there is nothing different between SRLG and MELG here.




Best Regards

Fatai

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