[ntp:questions] Are broadcasts by non-responsive servers used by clients?

Rod rglenist at netscape.net
Fri Oct 1 19:03:39 UTC 2004


I have a question regarding ntp broadcast operation as described on the
Association Management page.  The description:

"Once the offset is computed, the server continues as before and the client
sends no further messages. If for some reason the broadcast server does not
respond to client messages, the client will time out the volley and continue 
in listen-only mode with a default propagation delay."

Does this mean if the broadcast server does not respond that the broadcast
client will yet use the broadcasts to update its clock?  That'd be the 
behavior I'd expect, but do not find.

I've set up an ntp broadcast through a one-way link, and the broadcast 
client initiates a volley which times out after 8 failed messages, but it
never uses the broadcast time.  The broadcast client ntpd writes 
"ntpd[6263]: recvfrom() fd=6: No route to host" to /var/log/messages,
which is expected.

Some checks on the system:  ethereal shows the packets arriving at the 
client at stratum 3, and iptables -Lv shows that the packets make it 
through the client firewall.  Subsequently, I've disabled the firewall 
on the client, and the ntp broadcast client still does not use the ntp
broadcasts.

Any help is appreciated!

Rod
________________________________________________________________________
ntp config files:
# Broadcast server
restrict default ignore

restrict 127.0.0.1

broadcast 158.184.160.255 minpoll 4

# Time from the stratum 2 servers:
server 158.184.160.2
restrict 158.184.160.2 mask 255.255.255.255 nomodify notrap noquery

server 158.184.160.3
restrict 158.184.160.3 mask 255.255.255.255 nomodify notrap noquery

fudge   127.127.1.0 stratum 10

driftfile /etc/ntp/drift
broadcastdelay  0.008

authenticate no

keys            /etc/ntp/keys

________________________________________________________________________
# The broadcast client.
server  127.127.1.0     # local clock
fudge   127.127.1.0 stratum 10

broadcastdelay  0.008
broadcastclient

authenticate no
________________________________________________________________________
/sbin/ifconfig on the client:
eth0    inet addr:158.184.160.217  Bcast:158.184.160.255  Mask:255.255.255.0



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