> From: Francis Dupont <[EMAIL PROTECTED]>
> => the is_router flag is in fact very easy: if the NA is valid
> you take it and you get the transition table (I note u (unkown)
> the bottom semantical value, with R and H):
I don't have any "UNKNOWN" R/H state. It's either a host or a
router. And, initial value is always HOST.
> u -> H, u -> R: just note it
> u -> u, H -> H, R -> R: nothing to do
> H -> u, R -> u: should not happen (this is the effect of
I don't have problem with what to do when transition R->H or H->R
happens. The problem is how I detect this transition with certain
class of Neigbor advertisements, specifically those that omit target
link layer address. Do I process the R bit or not?
In RFC-2461, section 7.2.5, there is quite complex sentence (for
me)...
.....If the Override flag is clear and the
supplied link-layer address differs from that in the cache, then one
of two actions takes place: if the state of the entry is REACHABLE,
set it to STALE, but do not update the entry in any other way;
otherwise, the received advertisement should be ignored and MUST NOT
update the cache. If the Override flag is set, both the Override
flag is clear and the supplied link-layer address is the same as that
in the cache, or no Target Link-layer address option was supplied,
======================================
the received advertisement MUST update the Neighbor Cache entry as
follows: ...
So, depending on how you bind the or in ", or no Target", you may
get different implementations.
That's why I made the table (which I hope is clearer than above text)
and wanted have a definite answer. So, this is the correct left corner
then
....
REACHABLE | - | - | - | - | - |addr=TLL| - |addr=TLL
Address | - | - | - | - | STALE | STALE | STALE | STALE
=! TLL | - | - | - | - | - | R | - | R
----------|-----------------------------|-------|--------|-------|--------
OTHER | - | - | - | - | - |addr=TLL| - |addr=TLL
Address | - | - | - | - | - | STALE | - | STALE
=! TLL | - | - | - | - | - | R | - | R
==========================================================================
That is, if link layer is using addresses, ignore Neighbor
advertisements without TLL totally?
--
Markku Savela <[EMAIL PROTECTED]>
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