Hi,
The RFC 2460 says:
"Hop Limit 8-bit unsigned integer. Decremented by 1 by
each node that forwards the packet. The packet
is discarded if Hop Limit is decremented to
zero."
IMHO, this means: when the Hop Limit=0 the packet is discarded.
Now, if the packet is sent with Hop Limit=0, the forwarding (in the next hop)
decrements the Hop Limit and the result of 0-1 is 255 thus the packet is not dropped
but forwarded.
Kassi
-----Message d'origine-----
De : Markku Savela [mailto:[EMAIL PROTECTED]
Envoyé : mardi 28 octobre 2003 21:21
À : [EMAIL PROTECTED]
Cc : [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED]
Objet : Re: RFC 2460 issue
> Off the top of my head I know that RFC3493 needs to be updated since
> the IPV6_UNICAST_HOPS socket option now accepts 0 as a valid hop
> count. I really do not understand what a hop count of 0 implies and
> why we should bother updating the RFCs.
Heh, yes. I too wondered about what I should do if application sets TTL = 0. There are
two choices
a) Packets go to /dev/null (perhaps some obscure testing feature?)
b) Just let packets with TTL=0 go out.
I chose (b), because
- TTL is naturally checked only on fowarding, not when sending
own packets out. Thus, any TTL just gets accepted and sent.
If packet with TTL=0 is for this node, it is accepted (again, because TTL test is only
for forwarding).
Forwarding decrements TTL and if result is 0 or < 0, packet dropped (with appropriate
ICMP if needed).
I'm happy with above semantics. I don't see any need to worry about it too much.
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