John,
You are correct in that there are two tables. In classic routing, the first is
the Routing Information Base, or RIB. Protocols typically update the RIB as
conditions warrant (e.g., as routes are created or are broken).
At least in one implementation that I’ve worked with ;-), the FIB is “shadowed”
– that is, there is software watching for changes in the RIB, and those changes
are then propagated to the FIB. While the RIB is used for Layer 3 and above,
the FIB is optimized for Layter 2 forwarding. In AODVv2, as in any routing
protocol spec, my personal opinion is that we should avoid referencing the FIB
if possible.
Regards,
Stan
From: aodvv2-discuss-bounce@xxxxxxxxxxxxx
[mailto:aodvv2-discuss-bounce@xxxxxxxxxxxxx] On Behalf Of John Dowdell
Sent: Thursday, June 04, 2015 9:06 AM
To: AODVv2 Discuss
Subject: [aodvv2-discuss] Re: Section 6.5.2/Unconfirmed routes
Hi both
So just to be a little more explicit on terminology and usage here, I believe
we are discussing two tables; one is the “scratchpad” for AODVv2, and the
second is the live routing table, used for forwarding user traffic. Apologies I
am not sure about correct terminology but I believe the second is called the
Forwarding Information Base (FIB), and live routes are exported to the FIB from
the scratchpad. Please do correct my naming.
I also believe that routes in the scratchpad can be (based on the below) be
Unconfirmed (as in, under construction), or Confirmed (as in, the route is
fully constructed but may or may not be exported to the FIB).
I further believe that even if a route is withdrawn from the FIB, but still has
a status of Confirmed, it should not be expunged from the scratchpad but should
be held in reserve in case the route that has been exported becomes faulty.
Regards
John
On 3 Jun 2015, at 12:01, Victoria Mercieca
<vmercieca0@xxxxxxxxx<mailto:vmercieca0@xxxxxxxxx>> wrote:
Hi Lotte,
You are right, it would be better to explicitly define it, and we should
incorporate this text.
Kind regards,
Vicky.
On Wed, Jun 3, 2015 at 9:39 AM, Lotte Steenbrink
<lotte.steenbrink@xxxxxxxxxxxx<mailto:lotte.steenbrink@xxxxxxxxxxxx>> wrote:
Hi all,
while implementing Unconfirmed routes, I had a bit of a hang up with section
6.5.2., which says:
If the RteMsg containing AdvRte is a RREQ, the route is not yet
confirmed. It should be stored, so that a corresponding RREP can be
sent, but should not be used to forward data. If there is already a
matching route, this new route should be saved as an additional route
using the process below, and can replace the original route when
adjacency with the next hop is confirmed.
Because there is no mention of the word Unconfirmed, I first missed this part
while searching through the Draft for cues how to implement Unconfirmed
routes...
I'm wondering, would it make sense to explicitly write down the process hinted
at above? After all, it is a routing table ,not a FIB... It could have several
entries for one route. So the process could be something like this:
- if no other route exists and the RteMsg is a RREQ, add the entry and set it
to Unconfirmed.
- if another route exists and the RteMsg is a RREQ, add another entry and set
it to Unconfirmed
- if other route(s) exist and the RteMsg is a RREP:
- if the only other route is Unconfirmed, set it to confirmed.
- if there is an Active/Idle/Invalid route and an Unconfirmed route,
set the Unconfirmed route and expunge the old Active/Idle/Invalid route.
(maybe the third point plus subpoints could also be woven into section 6.5.1.)
Regards,
Lotte
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