[Xorp-users] RTT "Round Trip Time"

James Courtier-Dutton James Courtier-Dutton <james.dutton@gmail.com>
Sun, 15 May 2005 11:48:12 +0100


On 5/8/05, TTA Group <ttagroup@gmail.com> wrote:
> Hi,
> I'm a graduate student and my graduate project about "Round Trip Time"
> as router matrix. So I think to use XORP as my research environment.
> But I notice that the default xorp RIP matrix is "Hob Count". So does
> any one has any idea how I can make it RTT "Round trip time"? any help
> or suggestions in this subject or previous experience?
> 
> I appreciate your time.
> Tariq
> 
> ttagroup@gmail.com
> 

RTT has never been used as a routing protocol measurement for a very
good reason. RTT is dependent on how much traffic has to pass over a
link. That is, if you measure RTT with something like "ping".
Another measure of RTT could be the physical latency of a link without
any traffic on it. I.e. A Satellite link will have a higher latency
that an land based link.
As this RTT is therefore constant, one can just manually adjust the
"cost" of a link.
One has to then use a routing protocol that uses "cost" as a metric,
like for example OSPF.

So, what I am trying to say is that your current graduate project is
hardly worth attempting as the final outcome will not be of any use to
anyone.

But, something that would be extremely useful, would be to implement
something on the Xorp roadmap so that it arrives earlier. e.g. OSPFv2
or IGMPv3.

James