Date: Thu, 13 Aug 1998 16:39:05 -0700 From: bmah@CA.Sandia.GOV (Bruce A. Mah) To: Jeremy Shaffner <jer@jorsm.com> Cc: "Joe \"Marcus\" Clarke" <marcus@miami.edu>, freebsd-questions@FreeBSD.ORG Subject: Re: Traceroutes to Cisco Routers Message-ID: <199808132339.QAA29004@stennis.ca.sandia.gov> In-Reply-To: Your message of "Thu, 13 Aug 1998 17:41:07 CDT." <Pine.BSF.3.95q.980813173729.22777K-100000@mercury.jorsm.com>
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--==_Exmh_-389640468P Content-Type: text/plain; charset=us-ascii 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".) Bruce. --==_Exmh_-389640468P Content-Type: application/pgp-signature -----BEGIN PGP MESSAGE----- Version: 2.6.2 iQCVAwUBNdN5GKjOOi0j7CY9AQEi3QP+Nxz0EbzC3njFyVrJRu4D9tPN5+iv2OcN Oi+ixqBh95JJl+eo5Vz7lEF3fpMg+E6DoYT2/Pv7seqsBRmHl627elOOuBUk/T+C +zy2fZUGQE/QPlCgGOCqEJnLlMhJeVTEGxHS+0z3mTT2Zc2TDo6R2L1P5pHpyHam WJxJAqSn8fA= =ZYzq -----END PGP MESSAGE----- --==_Exmh_-389640468P-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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