Darren Reed writes: > On 26/02/09 07:57 PM, Sowmini.Varadhan at Sun.COM wrote: > > I don't know.. smells like a huge copy/paste project here :-) > > I can easily imagine, back when Solaris first arrived with a TTL > of 255, that they wanted to provide a knob in case some piece of > network hardware reacted badly because of a bug that assumed 255 == -1.
I don't think this is the sort of thing that necessarily requires imagination. A quick trip through memory lane (also known as the SCCS history ;-}) shows that all of the following parameters were added with the IPv6 project in 1999: ip6_def_hops tcp_ipv4_ttl tcp_ipv6_hoplimit icmp_ipv4_ttl icmp_ipv6_hoplimit udp_ipv4_ttl udp_ipv6_hoplimit Many of the folks involved with that project are still around and can probably answer why they added these parameters. (Unfortunately, I don't know where that old project gate might be, if it still exists at all. That would probably have better records.) My guess, if we're just guessing, is that they were added on spec: someone thought that they might be useful somewhere down the road. If we're doing a clean-up project here, then it's probably high time to figure out whether that initial speculation panned out. If they're not useful, then toss 'em. These two are special: ip_def_ttl - SID 1.5 ip.c, November 1991 Mentat update ip_broadcast_ttl - CR 1162269 That first one seems like it could be related to some RFC issue (though not clear what). That second one (thankfully) has a record. -- James Carlson, Solaris Networking <james.d.carlson at sun.com> Sun Microsystems / 35 Network Drive 71.232W Vox +1 781 442 2084 MS UBUR02-212 / Burlington MA 01803-2757 42.496N Fax +1 781 442 1677
