In the past, the MAE ATM switches ran ABR where you specified the MCR
and traffic was policed at a PCR of 2xMCR, although almost no one at
the MAEs actually used ABR on their connections. Almost everyone used
VBR-nrt and many did not even realize that the use of ABR could have
been beneficial.
With "best effort" PVCs, this really becomes moot although these are
still technically ABR.
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman@es.net Phone: +1 510 486-8634
In the past, the MAE ATM switches ran ABR where you specified the MCR
and traffic was policed at a PCR of 2xMCR, although almost no one at
the MAEs actually used ABR on their connections. Almost everyone used
VBR-nrt and many did not even realize that the use of ABR could have
been beneficial.
To be even more precise, MAE-ATM runs ABR
nternally, but didn't speak the protocol
over the UNI to the routers.
In this mode, the switches being used would
emulate VBR-nrt but actually do some input
buffering and shaping to smooth out bursts.
This came in very handy for older router interfaces
which couldn't shape on their own.
I never had an ABR-speaking router to try it with.
With "best effort" PVCs, this really becomes moot although these are
still technically ABR.
Agreed, though I'm not famiiliar with details of the
"best effort" service. And I'm pretty sure the reserved
and policed service is still there for folks who still
want to use it.
Steve
(former target-carrier)
Yes. They are still there.
They are both ABR services. The 'guaranteed' as they call is, has the PCR
at 2x MCR.
The 'best-effort' is MCR of 100 cps, PCR being somewhere around 1/2 port
speed.