potential problems with TTL = 0

Dale Smith (DSMITH@oregon.uoregon.edu)
Mon, 2 May 88 16:31 PDT

What is the current "correct" value to place for the TTL field? Can
someone with a Sequent Balance 21000 verify what the initial TTL value
is for TCP, UDP, and ICMP packets?

The reason for this query is that I am having problems delivering mail
to uunet.uu.net which is a Sequent Balance 21000. I have observed TCP
packets from uunet.uu.net being dropped by my gateway because the TTL
was 0. This seems to only happen for TCP traffic. I can ping uunet and
get response of 1-2 seconds. I can use nslookup to query uunet.uu.net
using datagram (UPD) mode. However, use of any TCP based service to
uunet causes lots of TCP packets from uunet to be dropped at my gateway
with TTL = 0. I have captured and looked at the UDP and ICMP packets
from uunet and they have different, but adequately large TTL values.
The folks at uunet say they are running some beta version of TCP/IP.

So, is there anyone out there from Sequent who can verify that this is
or is not a known problem? Can someone with a Balance 21000 who is
running beta-version TCP software look at what the initial TTL value is?


Dale Smith, Assistant Director of Network Services

Internet: dsmith@oregon.uoregon.edu
BITNET: dsmith@oregon.bitnet
Voice: (503) 686-4394
USmail: University of Oregon
        Computing Center
        Eugene, OR 97403-1212

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