hsw@TYCHO.ARPA.UUCP (02/02/87)
Attached is a set of ICMP re-direct messages that my host (TYCHO 10.0.0.126) received this morning. The packets were being sent to BBNCC-COLUMBIA.ARPA (8.1.0.35) and were being sent thru the BBNNET2-ARPANET-GW (10.7.0.63, 8.3.0.9). The following round-the-world tour is the result. Do any of the gateway gurus have any words of wisdom on this? It seems awfully strange from where I sit! Why the hops to the MILNET and why the loops in the West Coast gateways? Howard Weiss --------------------------------------- ICMPIn: type = 5, code = 0 from 10.7.0.63 /* BBNNET2-ARPANET-GW */ ICMPIn: Redirect to 10.5.0.5 /* redirecting to BBN-MILNET-GW */ ICMPIn: Message original dest was 8.1.0.35 /* (26.2.0.49) on the milnet */ ICMPIn: type = 5, code = 0 from 10.5.0.5 /* BBN-MILNET-GW */ ICMPIn: Redirect to 10.0.0.68 /* redirecting to LBL-MILNET-GW */ ICMPIn: Message original dest was 8.1.0.35 /* (26.3.0.34) on the MILNET */ ICMPIn: type = 5, code = 0 from 10.0.0.68 /* LBL-MILNET-GW */ ICMPIn: Redirect to 10.5.0.51 /* redirecting to SRI-GW */ ICMPIn: Message original dest was 8.1.0.35 /* (128.18.1.0) on the SRINET */ ICMPIn: type = 5, code = 0 from 10.5.0.51 /* SRI-GW */ ICMPIn: Redirect to 10.4.0.51 /* redirecting to SRI-MILNET-GW */ ICMPIn: Message original dest was 8.1.0.35 /* (26.2.0.73) on the MILNET */ ICMPIn: type = 5, code = 0 from 10.4.0.51 /* SRI-MILNET-GW */ ICMPIn: Redirect to 10.0.0.68 /* redirecting to LBL-MILNET-GW */ ICMPIn: Message original dest was 8.1.0.35 /* (26.3.0.34) on the MILNET */ ICMPIn: type = 5, code = 0 from 10.0.0.68 /* LBL-MILNET-GW */ ICMPIn: Redirect to 10.5.0.51 /* redirecting to SRI-GW */ ICMPIn: Message original dest was 8.1.0.35 /* (128.18.1.0) on the SRINET */ ICMPIn: type = 5, code = 0 from 10.5.0.51 /* SRI-GW */ ICMPIn: Redirect to 10.4.0.82 /* redirecting to BBN-ENET-2-GW */ ICMPIn: Message original dest was 8.1.0.35 /* (8.3.0.8) on the BBN-NET-TEMP */ /* Wow - finally got there !! */ -------
brescia@CCV.BBN.COM.UUCP (02/03/87)
Howard, you seem to have captured a routing transient.
For about the past week, and through about 3pm EST Monday afternoon, there was
a growing problem with congestion on the arpanet. Because of this congestion,
the gateways (core, butterfly, and egp) were losing track of their neighbor
connections, and making a lot of changes to the routing information they
maintain. Between about 9am and noon EST, I had brought down various gateways
which had been providing redundant routes to satnet, wideband, and bbnnet.
Specifically, I had disconnected 8.3.0.9 (bbn2), 10.3.0.82 (bbn), 10.4.0.82
(bbn-e2), sri-wb (10.3.0.51), and css (10.2.0.25). This was an attempt to
provide single path routes, and reduce the gateway routing overhead. The
arpanet programmers will probably have some specific recommendations coming
out soon, because the current respite seems shaky.
For the gateways, we are designing methods to make the neighbor connections
more robust in the face of long delays, wildly varying delays, and long
internal queues. We aim to reduce the apparent instability in the internet
when the arpanet gets congested.
--
Attached is a set of ICMP re-direct messages that my host (TYCHO 10.0.0.126)
This specific set of redirects would be even more interesting if we knew when
they happened. I suspect it was around the time when I brought down the first
interface at 8.3.0.9 (other side of 10.7.0.63), around 9am EST. Please don't
be mislead by the redirects to various other gateways; this does not mean the
packets went to the sri-ethernet, or milnet. They went in and out the same
arpanet interface of each gateway which issued a redirect.
Additional information I could use would be how often and how long the
redirect flurry was going on. It does seem that the route settled after only
a 'short' time. This means that it is useful if your host retains network
route information over a longer time than the existence of a single tcp (e.g.
mail) connection.
ICMPIn: type = 5, code = 0 from 10.7.0.63 /* BBNNET2-ARPANET-GW */
ICMPIn: Redirect to 10.5.0.5 /* redirecting to BBN-MILNET-GW */
ICMPIn: type = 5, code = 0 from 10.5.0.5 /* BBN-MILNET-GW */
ICMPIn: Redirect to 10.0.0.68 /* redirecting to LBL-MILNET-GW */
ICMPIn: type = 5, code = 0 from 10.0.0.68 /* LBL-MILNET-GW */
ICMPIn: Redirect to 10.5.0.51 /* redirecting to SRI-GW */
ICMPIn: type = 5, code = 0 from 10.5.0.51 /* SRI-GW */
ICMPIn: Redirect to 10.4.0.51 /* redirecting to SRI-MILNET-GW */
ICMPIn: type = 5, code = 0 from 10.4.0.51 /* SRI-MILNET-GW */
ICMPIn: Redirect to 10.0.0.68 /* redirecting to LBL-MILNET-GW */
ICMPIn: type = 5, code = 0 from 10.0.0.68 /* LBL-MILNET-GW */
ICMPIn: Redirect to 10.5.0.51 /* redirecting to SRI-GW */
ICMPIn: type = 5, code = 0 from 10.5.0.51 /* SRI-GW */
ICMPIn: Redirect to 10.4.0.82 /* redirecting to BBN-ENET-2-GW */
Mikehsw@TYCHO.ARPA.UUCP (02/04/87)
Mike, The redirects were received when ack packets were being sent to BBCC-COLUMBIA in response to an smtp message that was received by TYCHO at 12:10:06 EST. The flurry of redirects did end quickly and we do keep the redirect state information until the network code is restarted. Also, later in the day (after 1630 EST) there was another flurry of redirects which lasted much longer than the one I showed in my earlier message, but I will not send this one out because there are several ftp connections that were being redirected and I cannot tell which redirect is from which connection. Howard -------