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Re: Thomas Narten's DISCUSS vote
> Note: The decrementing of the TTL is one of the usual
> actions that takes place when forwarding a packet. Packets
> originating from the same node as the encapsulator do not
> have their TTLs decremented, as the sending node is
> originating the packet rather than forwarding it.
>
>Charile Lynn has sent mail dissenting, claiming that it would be a bad
>thing to do this since it would imply that this would imply that IPSEC
>tunnels change the Internet Routing Topology, and if so, they might have
>to conform to all requirements for Internet Routers. (I don't think
>that's the case today for normal IP-IP tunnels, is it?)
This is the most persistent zombie ever to haunt the Mobile IP
working group. It has been dormant for a while now, and as
reported in Jim Solomon's book on Mobile IP, rfc1883 (ipv6) has had
a lot to do with this. perhaps this quote from rfc1883 helps clarify
things:
Note: it is possible, though unusual, for a device with multiple
interfaces to be configured to forward non-self-destined packets
arriving from some set (fewer than all) of its interfaces, and to
discard non-self-destined packets arriving from its other interfaces.
Such a device must obey the protocol requirements for routers when
receiving packets from, and interacting with neighbors over, the
former (forwarding) interfaces. It must obey the protocol
requirements for hosts when receiving packets from, and interacting
with neighbors over, the latter (non-forwarding) interfaces.
The case that concerns us is not quite covered by the above note.
Perhaps this addition will suffice:
Furthermore, with respect to any of its forwarding interfaces a device
behaves as a host when originating or consuming a packet (instead of
forwarding it into or out of the interface).
Hope this helps,
-gabriel