Poor mil/arpa performance


Mike Muuss (mike@BRL.ARPA)
Thu, 27 Feb 86 18:50:49 EST


As another data point, I offer the following two
PING studies, conducted 1820-1840 EST from BRLNET3 (192.5.23.x):

----brl-tac.arpa PING Statistics----
204 packets transmitted, 203 packets received, 0% packet loss
round-trip (ms) min/avg/max = 60/230/4860

----nosc.arpa PING Statistics----
38 packets transmitted, 38 packets received, 0% packet loss
round-trip (ms) min/avg/max = 320/434/840

----seismo.css.gov PING Statistics----
554 packets transmitted, 148 packets received, 73% packet loss
round-trip (ms) min/avg/max = 2300/13914/28960

BRL-TAC is on the same MILNET IMP as our (two) Gateways. The max of 4,860ms
implies that we are suffering some interface blocking (even though
we do RFNM counting), but examining the PING log only showed one such
packet.

NOSC is on the West Coast (BRL is in Maryland) -- transcontinental MILNET
bandwidth seems just fine.

SEISMO is on the ARPANET in Washington DC, on the other side of the core
from us, yet network performance to them is awful.

I mention this because BRL has business (of significant volume) with
a number of ARPANET sites, mainly Utah, Seismo, Berkeley, and BBN (yes,
the Butterfly part of BBN seems to be on the ARPANET, and having them
debug our Butterfly through the core drives them bonkers).

DISCUSSION

Given the difficulties in getting trunks installed (in understand, and
you have my sympathies), I think DCA has done a bang-up job of keeping
the MILNET in good, working order. It's effective to use at most any
hour, and that is good. They deserve our congratulations!

There exists this bottleneck called "the MIL/ARPA" bridges, and the
additional complications of the "EGP extra hop" problem which causes
up to 3 times as much IMP Trunk bandwitdh to be used for each packet.
(ie, BRL-GATEWAY to our EGP-speaking core peer via MILNET, from him
to the MIL/ARPA bridge via MILNET, then to the destination via ARPANET).
The same sort of thing can happen on returning packets too (depends on
whether there is a gateway involved on the ARPANET side, usually yes).

CONCLUSIONS

The MILNET is sound. Praise DCA!

The MIL/ARPA bridges are teetering under the load. They are important.
EGP makes it worse. What can we do?

        Best,
         -Mike



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