I suspect there's a confusion here. See inline below, pls:
> In the general case we have to assume that every router has been configured
> with a different value for the time that it's operator thinks it will need.
> So the problem is how to make sure that the network has a consistent view
> of the max value.
> My thought was that since the set of LSPs that were used to calculate the
> topology had to be consistent over the network (or the network would be
> unstable), then if the delay parameter was imbedded in the LSPs it would
> be consistent amongst the routers that were converging.
I meant the same announcement mechanism in my message--stick a TLV in an
> By using the value extracted from the current topology info, you avoid
> a whole load of messy protocol associated with routers joining, or leaving
> and wanting to change the value - it just happens automatically.
I assume you mean the standard link-state database synchronization
mechanisms here. Yes, I meant to use the same in my message.
> By using historical values - as you seem to propose, you need to consider
> how you propose to synchronize the addition or removal of routers from
> the max-time algorithm. I am proposing that this happen automatically
> as part of the convergence calculation, whilst your approach needs to
> consider quasi asynchronous removal of a router that has the net max
> value, just as the topology changes. Extracting the info from the LSPs
> makes such actions a synchronous event.
This is where you lost me.
Injection of info from newly joined routers and removing stale information
from unreachable routers is a solved problem. Have I missed something?
> If I look at your second para:
>> While this would work algorithmically, I would instead prefer finding the
>> max among all available announcements, whether the corresponding nodes are
>> momentarily reachable or not.
>> This would be more robust,
> What can be more robust than extracting the parameter from the set of
> topology info that EVERYONE is using for THIS transition?
>> easier to debug,
> Not convinced, you know which routers are in the net, you know what the
> time should be. The other way you get strange bugs due to the
> asynchronous aging of LSPs
>> and save extra fluctuations when the network topology changes.
> I am not sure how much of a problem this is in practice.
>> If any of
>> the routers becomes unreachable for an extended period of time, its
>> LSAs/LSPs would finally age out and hence taken out of consideration.
> In the past this was a garbage collection activity with no topology
> significance, and did not need to be synchronized. We are now making
> it a topology significant event that needs to be synchronized so that
> max-time is synchronously removed across the network.
I think above you're assuming that every router would age out stale
LSPs/LSAs independently. Both IS-IS and OSPF have mechanisms to flush an
LSP/LSA from the domain once it has aged in one of the routers.
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