From: James Keane (jameskeane@yahoo.com)
Date: Fri Aug 12 2005 - 00:27:50 GMT-3
--- gladston@br.ibm.com wrote:
> Trying to understand these results. Any help
> appreciated.
>
> Rack2R6#trac 148.5.135.13 (serial of bb2)
>
> Type escape sequence to abort.
> Tracing the route to 148.5.135.13
>
> 1 148.5.226.2 4 msec 4 msec 4 msec
> 2 148.5.235.5 16 msec 16 msec 16 msec
> 3 *
> 148.5.135.13 24 msec *
>
> Isn't that * on third line strange?
>
>
> Debug ip icmp on bb2:
>
> .Feb 28 21:21:57: ICMP: time exceeded rcvd from
> 148.5.235.5
> .Feb 28 21:21:57: ICMP: time exceeded rcvd from
> 148.5.235.5 *
>
>
> I expected something like this:
>
> Rack2R6#tra 150.100.1.254
>
> 1 148.5.146.4 4 msec
> 2 148.5.14.1 20 msec
> 3 150.100.1.254 24 msec
>
>
> Testing trace to loopback of bb2:
>
> Rack2R6#trac 148.5.13.1
>
> Type escape sequence to abort.
> Tracing the route to 148.5.13.1
>
> 1 148.5.226.2 0 msec 0 msec 4 msec
> 2 148.5.235.5 16 msec 16 msec 16 msec
> 3 148.5.135.13 24 msec * *
>
>
> Just one probe does not change the result:
>
> Rack2R6#trace
> Protocol [ip]:
> Target IP address: 148.5.135.13
> Source address:
> Numeric display [n]:
> Timeout in seconds [3]:
> Probe count [3]: 1
> Minimum Time to Live [1]:
> Maximum Time to Live [30]:
> Port Number [33434]:
> Loose, Strict, Record, Timestamp, Verbose[none]:
> Type escape sequence to abort.
> Tracing the route to 148.5.135.13
>
> 1 148.5.226.2 4 msec
> 2 148.5.235.5 96 msec
> 3 *
> 4 148.5.135.13 24 msec
>
>
> Doing a little more tests on traceroute, I noticed
> that repeated behavior:
>
> When the router is on the path (r5 on the test) it
> answers with 3 port unreachable.
>
> Rack2R3#trace 148.5.2.1
>
>
> 1 148.5.235.5 12 msec 12 msec 8 msec
> <---------- three RTT reported
> 2 148.5.235.2 24 msec * 20 msec
>
>
> Rack2R5#deb ip icmp
>
> .Feb 28 22:20:56: ICMP: time exceeded (time to live)
> sent to 148.5.235.3 (dest was 148.5.2.1)
> .Feb 28 22:20:56: ICMP: time exceeded (time to live)
> sent to 148.5.235.3 (dest was 148.5.2.1)
> .Feb 28 22:20:56: ICMP: time exceeded (time to live)
> sent to 148.5.235.3 (dest was 148.5.2.1)
>
> When the router is the end, is answers only 2 port
> unreachable:
>
> Rack2R3#trace 148.5.5.1
>
>
> 1 148.5.235.5 12 msec * 8 msec
> <------------- one RTT is missed
>
>
> Rack2R5#
> .Feb 28 22:22:33: ICMP: dst (148.5.5.1) port
> unreachable sent to 148.5.235.3
> .Feb 28 22:22:36: ICMP: dst (148.5.5.1) port
> unreachable sent to 148.5.235.3
>
> Do you know the reason the router just answer two
> packets?
>
>
This archive was generated by hypermail 2.1.4 : Sun Sep 04 2005 - 17:01:19 GMT-3