Cell Relay Archive[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index][Thread Index][Author Index][Subject Index] Re: What goes in the peak cell rate of a UBR connection?
In article <56vvhm$k0g@bcarh8ab.bnr.ca> smiller@bnr.ca (Scott Miller) writes: >If I'm setting up a best-effort connection, what should I use for the PCR? I *hate* that term "best-effort". It is taken in the ATM world to mean "worst effort". That's what UBR means. >I've been told that it should be set to the line rate, because otherwise the >switch can use GCRA to tag based on the provided rate, and any cell other than >the first in a burst will be tagged. (since it has no specified burst size) >On the other hand, UNI 3.1, 3.6.2.4 says that "the user need not conform to the >signalled PCR and the network may enforce a PCR other than the signalled PCR", >which tends to indicate that the PCR is more or less meaningless to the switch. I'd go with that last clause. In UBR, you get available, unreserved, low-priority bandwidth. It's *unspecified* bit rate, so why worry about what rate to specify? No promises, just spare capacity. With VBR, this stuff really matters. -- Fred R. Goldstein k1io fgoldstein@bbn.com BBN Corp., Cambridge MA USA +1 617 873 3850 Opinions are mine alone; sharing requires permission. |
|