[ntp:questions] Re: Multicast TTL and FreeBSD trouble

Per Hedeland per at hedeland.org
Sun Aug 21 20:27:57 UTC 2005


In article <4308D64E.6030007 at gis.net> mayer at gis.net (Danny Mayer) writes:
>David L. Mills wrote:
>> Guys,
>> 
>> Wash your mouth with soap. The scheme does not conform to the anycast 
>> model; it does conform to the manycast model, where the intent is to 
>> capture a plurality of servers, not just a single one. I have not 
>> changed the ttl code in a decade. If it behaves differently in Linux and 
>> FreeBSD, somebody else has changed the code or the operating system has 
>> a mind of its own.
>> 
>> Dave
>
>Nothing to wash, Dave. I know it hasn't changed. I agree that getting 
>different results on different O/S's indicates an O/S problem rather 
>than an ntp problem. I have yet to look at the manycast model, too many 
>other things to work on...

Uh, I know that there are issues with the source code management for the
reference implementation, but this is getting silly. Here are excerpts
from a diff between 4.1.2 and 4.2.0, both downloaded from ftp.udel.edu:

--- ntp-4.1.2/ntpd/ntp_proto.c  Thu Jan 17 22:27:47 2002
+++ ntp-4.2.0/ntpd/ntp_proto.c  Tue Oct  7 12:21:39 2003
...
                HTONL_FP(&peer->xmt, &xpkt.xmt);
-               sendpkt(&peer->srcadr, peer->dstadr, peer->ttl, &xpkt,
-                   sendlen);
+               sendpkt(&peer->srcadr, peer->dstadr, sys_ttl[peer->ttl],
+                   &xpkt, sendlen);
                peer->sent++;
...
        }
-       sendpkt(&peer->srcadr, peer->dstadr, peer->ttl, &xpkt, sendlen);
+       sendpkt(&peer->srcadr, peer->dstadr, sys_ttl[peer->ttl], &xpkt,
+           sendlen);
 

Sure looks like a significant change to me... - maybe not to the
manycast model, but then no-one has been suggesting that there are
problems with that. The issue at hand is the semantics of the 'ttl'
option for the 'broadcast' command.

--Per Hedeland
per at hedeland.org




More information about the questions mailing list