Date: Thu, 13 Aug 1998 19:12:56 -0500 (CDT) From: Jeremy Shaffner <jer@jorsm.com> To: "Bruce A. Mah" <bmah@CA.Sandia.GOV> Cc: "Joe \"Marcus\" Clarke" <marcus@miami.edu>, freebsd-questions@FreeBSD.ORG Subject: Re: Traceroutes to Cisco Routers Message-ID: <Pine.BSF.3.95q.980813191222.29655G-100000@mercury.jorsm.com> In-Reply-To: <199808132339.QAA29004@stennis.ca.sandia.gov>
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On Thu, 13 Aug 1998, Bruce A. Mah wrote: > If memory serves me right, Jeremy Shaffner wrote: > > On Thu, 13 Aug 1998, Joe "Marcus" Clarke wrote: > > > > Cisco throttles ICMP unreachables so that only 2 unreachables per second > > > are sent. The result puts a star in one of the fields: > > > > > > i.e. (200 ms) (200 ms) * > > Whew, I guessed right! :-) > > > Fair enough. But it's dropping the second and not the third. > > > > And it doesn't explain why non-Unix OS's trace to it fine. > > I can't speak for MacOS, but the Win95 tracert command uses ICMP echo requests > (just confirmed via tcpdump), while all of the UNIX traceroute programs use > UDP packets to arbitrary, high-numbered UDP ports. Presumably the Cisco IOS > doesn't rate-limit ICMP echo replies in the same way that it does ICMP echo > requests. > > (In an earlier message, you asked if the UNIX traceroutes all shared a common > code base, and AFAIK the answer is "yes".) > Well..that seems to be it. Thanks everyone. -===================================================================- Jeremy Shaffner JORSM Internet Senior Technical Support Northwest Indiana's Premium jer@jorsm.com Internet Service Provider support@jorsm.com http://www.jorsm.com -===================================================================- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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