Re: MILNET/?/UMDNET/SURA/GWU-GATE traffic question


Stephen Wolff (steve@note.nsf.gov)
Thu, 07 Jan 88 05:09:28 -0500


You're being misled by one of the technical differences between SURANET
and MILNET. GWUVM is a host (128.164.1.234) on one of the campus
networks (128.164) connected via SURANET (128.167) to the rest of the
Internet. SURANET, like most (but not all) mid-level nets in the NSFNET,
is composed of IP routers (in SURANET'S case, Proteon P4200s) linked
together by serial lines.

What Record Route is showing you is the packet traveling from
128.167.33.1 - presumably the GWU_campus_net-to-SURANET P4200 gateway at
GWU - (but why it spent so much time there I don't understand) to
128.167.11.2 - the next P4200 (which happens to be at NSF) - to the
principal node of SURANET at University of Maryland, College Park, where
it is loaded onto MILNET. That is in fact the most direct route there
is. Thereafter, there is quite possibly as much "hopping around" on the
packet's way to LANL via MILNET, but because MILNET uses a distinct
communications subnet (based on the PSNs) that operates below the
IP level, that's all invisible to Record Route. I.e., since P4200s are
gateways as well as packet switches, each has a "host" number and so
leaves a fewmet for Record Route, but Record Route can't see the MILNET
packet switches.

>From just behind the SURANET gateway at NSF, I see RTTs of 1500 ms or so
to MILNET-GW.LANL.GOV; this seems totally unreasonable. Perhaps there
is congestion at the UMd gateway to MILNET which, combined with the
suspect behavior of the SURANET gateway at GWU, might cause your users'
connections to time out. I suspect the SURANET folks are conducting
their own investigation and we'll hear from them in due course...

-s



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