Cell Relay Archive

Cell Relay Retreat>List Archive>month:1997-Jan> msg00276



[Date Prev][Date Next][Thread Prev][Thread Next]  
  [Date Index][Thread Index][Author Index][Subject Index]

Re: connectionless and connection-oriented

  • From: ws@shore.net (William Stallings)
  • Date: Fri, 31 Jan 1997 09:43:45 -0500

In article <5cs812$204@src-news.pa.dec.com>, murray@pa.dec.com (Hal
Murray) wrote:


> ABR does not specify a minimum cell rate.  That's a different dimension
> alltogether.  ABR is Available Bit Rate.  It requires some sort of
> feedback so that the client can figure out how much bandwidth is
> available and adjust its transmission behavior to avoid lost cells.
> 
> Implementing ABR is not simple.  There are two competing camps - rate
> based and credit based.
> 

ABR does specify a minimum cell rate. The default value is 0 but the user
can request a nonzero MCR and that is then guaranteed by the network (if
the connection is accepted). ABR, unlike UBR, provides fair access to the
network--one user is not allowed to crowd out other ABR users.

The rate-based camp has won, at least in the ATM forum, which uses rate
based in the current (version 4.0) traffic management spec.

Bill

|                | Descriptions, errata sheets and discount order info |
| Bill Stallings |              for my current books and               |
|  ws@shore.net  |       information on my forthcoming books at        |
|                |              http://www.shore.net/~ws               |