<hat>Author of compliment implementation</hat>
Hi Alvaro,
I don’t necessarily agree that the only case where the links with
MaxLinkMetric will be used is when there is no other path. One could have
a situation where an alternate path existed but the aggregate cost was
greater than 64K. I agree this is highly unlikely in real deployments but
very likely in test topologies. Hence, I’d leave the section 4 text as is
and modify the section 3 text.
MaxLinkMetric
The metric value indicating that a router-LSA link (see Section 2)
should strongly discourage the usage for transit traffic. It is
defined to be the 16-bit binary value of all ones: 0xffff.
Thanks,
Acee
On 4/14/16, 9:28 AM, "Alvaro Retana (aretana)" <[email protected]> wrote:
>On 4/13/16, 6:31 PM, "OSPF on behalf of Acee Lindem (acee)"
><[email protected] on behalf of [email protected]> wrote:
>
><hat>author<hat>
>
>Acee:
>
>Hi!
>
>>>Sure, 4 reads the other way but "deployment considerations" . I'm not
>>>saying how it must be read, just saying it is possible to read the
>>>stronger language of 3 another way.
>>>
>>>I'm not trying to argue, I'm trying to explain why we are here.
>>
>>One of the authors or myself will write an errata to clarify this
>>definition.
>
>What do you have in mind?
>
>I may be too close to the text myself to tell where we should change
>something. Even if we interpret the "should not" in Section 3 as if it
>was "SHOULD NOT", it is still not a "MUST"...and the obvious reason the
>link would be used is if there isn't another path.
>
>There is one part which I think can be clarified (only including the
>change):
>
>NEW>
>4. Deployment Considerations
>...
> on using them rather than the path through the stub router. If the
> path through the stub router is the only one, the routers of the
> first type will not use the stub router for transit, while the routers
> of the second type will still use this path, which may result in a
>routing
> loop.
>...
>
>
>
>I'm open to other suggestions.
>
>Thanks!
>
>Alvaro.
>
>
>
>CURRENT TEXT>
>3. Maximum Link Metric
>
> Section 2 refers to the cost of all non-stub links as MaxLinkMetric,
> which is a new fixed architectural value introduced in this document.
>
> MaxLinkMetric
> The metric value indicating that a router-LSA link (see Section 2)
> should not be used for transit traffic. It is defined to be the
> 16-bit binary value of all ones: 0xffff.
>
>4. Deployment Considerations
>
> When using MaxLinkMetric, some inconsistency may be seen if the
> network is constructed of routers that perform an intra-area Dijkstra
> calculation as specified in [RFC1247] (discarding link records in
> router-LSAs that have a MaxLinkMetric cost value) and routers that
> perform it as specified in [RFC1583] and higher (do not treat links
> with MaxLinkMetric cost as unreachable). Note that this
> inconsistency will not lead to routing loops, because if there are
> some alternate paths in the network, both types of routers will agree
> on using them rather than the path through the stub router. If the
> path through the stub router is the only one, the routers of the
> first type will not use the stub router for transit (which is the
> desired behavior), while the routers of the second type will still
> use this path.
>
> On the other hand, clearing the R-bit will consistently result in the
> router not being used for transit.
>
> The use of MaxLinkMetric or the R-bit in a network depends on the
> objectives of the operator. One of the possible considerations for
> selecting one or the other is in the desired behavior if the path
> through the stub router is the only one available. Using
> MaxLinkMetric allows for that path to be used while the R-bit
> doesn't.
>
>
_______________________________________________
OSPF mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/ospf
