Subject: [manet] DLEP: request for new metric type

From: Teco Boot <[email-masked]>
Date: Fri, 30 Mar 2012 17:38:22 +0200

Stan,

Seen the discussion on hop-count and probably lots of other
nice to haves, an employee of a random router vender would 
easily get crazy to get all of this in a useful metric for 
the routing protocols.

I suggest to define a new metric type, to be used by modems,
to provide a dimensionless value that is used directly in the 
routing protocol. After a bit of discussion, we have a nice 
outcome of a 12-bit compressed form of a link metric OLSRv2.
http://tools.ietf.org/html/draft-ietf-manet-olsrv2-14#section-6.2

You may have a need for a 16-bit uncompressed dimensionless value
for OSPF. You could opt for a / 256 of the decompressed value
or go for another metric type. Important: OSPF needs the metric 
for outgoing traffic, OLSR for incoming traffic (OLSR transfers 
it to neighbor with hello). 

You could use the Neighbor Incoming / Outgoing Metric bits, you 
have the 4-bit placeholder already. 

With MAC address-block TLVs, assuming a 6-byte MAC address with 
first 3 bytes mostly being equivalent, the space per neighbor 
would be 5 bytes. Not that bad. But to make use of this, you
may need to have repeatedly having send this info instead of
having a reliable transport inside DLEP. This needs validity 
timers, so it is not a minor change.

Teco

---

From: Henning Rogge <[email-masked]>
Date: Sat, 31 Mar 2012 10:46:48 +0300

> have the 4-bit placeholder already.
If Layer-2 data is available, it should be exported in "raw" format by
the DLEP service/server. Especially data that cannot be easily
calculated by the connected computer like "Throughput" (real one, not
just hardware transmission speed), Transmission loss and transmission
attempts.

And for Radios we definitely need Frequency and Bandwidth (width of
the radio channel in Hz). These two values are also interesting to use
in the "request link characteristic" message to reconfigure a radio.

> timers, so it is not a minor change.

You mean space including your dimensionless metric TLV?

Something different, is the addition of IPs to the DLEP messages
really a common usecase? DLEP defines the radio to be a layer-2 bridge
to the ethernet (most likely VLAN tagged to separate it from the
control stream), so the radio/modem does not need any IP address
except for some linklocal one on the control interface.

Henning Rogge
-- 
Steven Hawkings about cosmic inflation: "An increase of billions of
billions of percent in a tiny fraction of a second. Of course, that
was before the present government."