To: p8021 <p8021@nic.hep.net>
From: Peter Wang/HQ/3Com <Peter_Wang@3mail.3Com.COM>
Date: 19 Mar 96 14:48:45 EDT
Subject: GARP Operating Mode

To make the relationships among bridge operating modes clearly and thereby 
defining proper transitions between operating modes to accomodate FDB running 
out of space and compatibility with routers running IGMP, I suggest that the 
following changes be made to the draft 1p spec.:

- Reorganize such that only two distinct modes (i.e. 802.1D and GARP) are 
  defined at the top level.  All of the ports of a bridge must operating in
  the same mode.
- Within the GARP mode, two operating preferences are defined (broadcast/prune 
  <BC/P> vs. specific membership <SM>).
- BC/P puts preference on recording the filtering entries while assuming the 
  default is JoinAll.
- SM puts preference on recording the forwarding entries while assuming the 
  default is LeaveAll.
- The default preference for a bridge running in GARP mode shall be BC/P.
- The transition from BC/P to SM shall be invoked manually via management 
  functions, so as not to be confused with the LeaveAll issued as part of
  the garbage collection process.
- If a GARP bridge port is running with SM preference and receives a JoinAll
  or runs out of FDB space, the port should transition to BC/P preference.

Peter