Subject: Comments on draft-ietf-zeroconf-ipv4-linklocal-02.txt

From: Bernard Aboba <[email-masked]>
Date: Mon, 26 Mar 2001 15:28:41 -0800 (PST)

Find enclosed some comments on the IPv4 linklocal draft. Despite the
length of the review, most of these represent minor changes in wording.

http://www.drizzle.com/~aboba/zeroconf/stuart.txt

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From: "Bernard Aboba" <[email-masked]>
Date: Wed, 28 Mar 2001 09:21:37 -0800

" As far as I understood the draft, that situation was just to enable
remote connection to a specified link-local subnet (the remote client
accesses it specified home network through its "gateway" between link-local
subnet and internet, for example). Thus the purpose of this sentence is NOT
"bridging two segments", is it ? "

Since we are talking about "IPv4 linklocal", if the VPN gateway is
forwarding packets to and from a linklocal address, then it MUST be doing so
while acting as a bridge -- if it is decrementing TTL, then it is acting as
a router -- and such forwarding is forbidden in the spec.

 > Here the remote client MUST NOT behave as a bridge. Or did I miss
something ?

The VPN gateway is acting as a bridge... not the remote client. The point I
was trying to make is that most VPN gateways today do not have bridging
capability. You can't just use any VPN protocol to do this -- IEEE 802
requires adherence to the hard invariants, which include non-duplication and
ordered delivery. You can do this by tunneling PPP BCP over L2TP, or
alternatively (as has been proposed) by tunneling Ethernet directly over
L2TP while running 802.1D or w.