From: Paul_Frantz@BayNetworks.COM (Paul Frantz)
To: Floyd_Backes@3mail.3Com.COM
Cc: asayed@fox.nstn.ca, mmcneali@cisco.com, p8021@nic.hep.net,
        alonge_ken@po.gis.prc.com
Subject: Re: Re: REVISION TO SDE
Date: 24 Nov 1995 22:46:01 GMT

A couple of comments with respect to Floyd's e-mail:

Implicit tagging and protocol sensitivity are not quite the same thing.
In a protocol-sensitive switch you could  map each packet to a
VLAN based on the network address, or you could map based on the
(protocol type, ingress port #) tuple.  This distinction is similar to the
MAC address-based vs. port-based distinction in protocol-insensitive
switches. If you map based on network address, you can use implicit
tagging, albeit at the cost of extra complexity for dealing with packets
lacking useful network addresses such as bootp or NetWare get nearest 
server queries. Despite the fact that implicit tagging can work here, you
might choose to use explicit tagging in some parts of the network to
facilitate the design of simple, high-performance core switches.
If you map based on the (protocol type, ingress port#) tuple
you need explicit tagging.

My recollection of the  802.10 presentation to 802.1 is that it did 
NOT suggest that 802.10 is  ill-suited for VLAN tagging.  
To the contrary it suggested that 802.10 is very well suited to VLAN
tagging, but since there is a requirement in the 802.10 spec. that all
implementations claiming conformance shall provide either encryption or
authentication, 802.10 suggests 802.1 should not recommend use of 802.10
for VLANs without adding a requirement for encryption or authentication.
Whether relaxing the 802.10 requirement for encryption/authentication is
in the best interests of 802 as a whole and of the user community seems
like a question worth discussing.

I'm in full agreement with Keith and Floyd that 802.1 has its work cut out
for it in defining the mappings among the different types of VLANs. This
does not mean we shouldn't also be working on the problems of standardizing
operation *within* particular types of VLANs.

-- Paul