Subject: Re: [Isis-wg] operational problem might be solved bysomehowextending current IS-IS

From: Pierre Francois <[email-masked]>
Date: Tue, 28 Sep 2010 19:56:40 +0200

Peter,

Well, you would simply find yourself in a case where two neighboring nodes are 
impacting each other's link metrics :-)

Pierre`;

On 28/09/10 19:50, Peter Ashwood-Smith wrote:
>
> Tony,
>
> That's pretty elegant .. one quick question.
>
> What would be the proposed semantics if both ends sent a reverse metric
> increment?
>
> Peter
>
>
> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On Behalf
> Of Tony Li
> Sent: Tuesday, September 28, 2010 3:59 AM
> To: Les Ginsberg (ginsberg)
> Cc: Mike Shand (mshand); [email-masked]
> Subject: Re: [Isis-wg] operational problem might be solved
> bysomehowextending current IS-IS
>
>
> Les,
>
> There is a semantic that would accomplish that, however.
>
> Suppose that we define an IIH TLV that is the "reverse metric increment".
>
> On reception on a PTP link, the receiver adds the value in the TLV to its
> normally configured metric and advertises the result instead of its normal
> link metric.
>
> This requires zero participation from any other IS, and if it is not
> understood by the receiving IS, fails safely and gracefully: nothing
> changes.
>
> Tony
>
>
> On Sep 28, 2010, at 12:03 AM, Les Ginsberg (ginsberg) wrote:
>
>> Mikael -
>>
>> If you wish traffic to be directed away from a particular node/link then
>> clearly the upstream routers have to calculate the cost in the same way
>> that the neighbors on the circuit do. Waiting until the packet arrives
>> at the node in question to use the adjusted cost will create forwarding
>> loops in cases where the lowest cost path from the node in question to
>> the destination traverses a path via an upstream router. So this change
>> is NOT confined to the neighbors.
>>
>>    Les
>>
>>
>>> -----Original Message-----
>>> From: Mikael Abrahamsson [mailto:[email-masked]]
>>> Sent: Monday, September 27, 2010 11:34 PM
>>> To: Les Ginsberg (ginsberg)
>>> Cc: [email-masked]; Mike Shand (mshand)
>>> Subject: RE: [Isis-wg] operational problem might be solved
>>> bysomehowextending current IS-IS
>>>
>>> On Mon, 27 Sep 2010, Les Ginsberg (ginsberg) wrote:
>>>
>>>> So you are suggesting we change the basic operation of the protocol
>>> (how
>>>> it computes SPT) solely so that we can more conveniently do
>> link/node
>>>> maintenance every now and then. This is hard to justify.
>>>
>>> Well, as far as I see it the (IN+OUT) metric could be treated the same
>>> as
>>> the current metric and communicated to others in the same way. This of
>>> course means both ends need to know about this new standard way of
>>> computing metric, but nobody else would need to know about it as far
>> as
>>> I
>>> can see?
>>>
>>> --
>>> Mikael Abrahamsson    email: [email-masked]
>> _______________________________________________
>> Isis-wg mailing list
>> [email-masked]
>> https://www.ietf.org/mailman/listinfo/isis-wg
>
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