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.
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