Actually, only the Microsoft tracert command use ICMP echo packets in
traces. Cisco and unix implementations both send out UDP packets with
altered ttl's on high ports (334xx if I remember correctly).
The "3 probes" are just 3 packets sent out with the same ttl. Notice that
you have 3 RTT's after each hop in the trace. These are the response times
for the 3 packets that would have timed out at that particualar hop.
Traceroute doesn't provide you with min/avg/max times like ping does.
Since there are only 3 packets to each hop, the values wouldn't mean much.
In both implementations, the return packets are going to be ICMP TTL
exceeded's.
Jamie Byrne
At 01:28 PM 5/11/00 -0500, Mark Odiorne wrote:
> Yes, Tony, you are correct. These "probes" are the ICMP ping packets with
>some fiddling of the Time To Live counters. The messages you get back are
>TTL Expired messages from each of the hosts the Ping packets travel
>to/through.
>
> Mark O. (NA/DA)
>
>-----Original Message-----
>From: Tony Tsai
>To: [EMAIL PROTECTED]
>Sent: 5/11/00 10:49 AM
>Subject: What are the 3 Probe types for Trace?
>
>Hi,
>
>I am reviewing the TRACE command & response that you can get on a Cisco
>router. The book that I am reading from Cisco Press mentions that the
>time
>(3 of them) listed after reaching an intermediate host, represent the
>time
>required for each of the three probes to return.
>
>Does anyone know what are these 3 probes? Are they the same as the ones
>
>used by the Ping command? (as in round-trip min/avg/max)
>
>Here is the sample Trace report from the book I am reading:
>
>Router# trace aba.nyc.mil
>Type escape sequence to abort.
>Tracing the route to aba.nyc.mil (26.0.0.73)
>
>1. debris.cisco.com (172.16.1.16) 1000 msec 8 msec 4 msec
>2. barmet-gw.cisco.com (172.16.16.2) 8 msec 4 msec 4 msec
>3. external-a-gateway.stanford.edu (192.42.110.225) 8 msec 4 msec 4 msec
>...
>6. moffett-fld-mb.in.mil (192.52.195.1) 216 msec 120 msec 132 msec
>7. aba.nyc.mil (26.0.0.73) 412 msec * 664 msec
>
>Thank you.
>Tony
>
>
>
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