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


C. Philip Wood (cpw%sneezy@LANL.GOV)
Tue, 5 Jan 88 16:25:41 MST


LANL is used by a number of folks on (or with access to) the Internet.
When they cannot 'telnet' to our hosts here, they start calling us up
and telling us how to do our job. So far, none of the suggestions have
been very appealing. The current problem causing some users grief manifests
itself as follows:

        1. A user on GWUVM.GWU.EDU attempts to telnet to MILNET-GW.LANL.GOV.
        2. The connection times out.
        3. The user is pissed and calls us up.

I have tried various things on our end to find out what is going on. Here
are the things I found out when the problem was first reported:

        1. I could talk to GWUVM.GWU.EDU from our subnets but not
           directly from MILNET-GW.LANL.GOV.
           This made absolutely no sense.

        2. I sent 100 ICMP ECHO request's from MILNET-GW.LANL.GOV
           and 100 reply's were received. But, of the 100 reply's
           received about 20% had DUPLICATE SEQUENCE NUMBERS!

I was getting curious.

        3. I sent a more sophisticated ICMP ECHO packet with out much
           hope of a response. This one is coded up with the IP RECORD
           ROUTE option. Some hosts on the Internet actually respond
           to these, like our 4.3BSD hosts (a local modification),
           and A.ISI.EDU. I wish others would.

           Low and Behold, back came the following IP header and option:

           x00: x4f001400 IP header
           x04: x86450000 "
           x08: x11010000 "
           x0c: x80a401ea IP source GWU-GATE host GWUVM.GWU.EDU
           x10: x1a00005a IP destination MILNET host MILNET-GW.LANL.GOV
           x14: x01072728 IP option field NOP | RR option header
           x18: x80080a0e The UMDNET host TRANTOR.UMD.EDU
           x1c: x81020101 route UMD-BOGON-NET host 129.2.1.1
           x20: x80a70101 traversed SURA host 128.167.1.1
           x24: x80a70201 as SURA host 128.167.2.1
           x28: x80a70102 far SURA host 128.167.1.2
           x2c: x80a72101 as SURA host 128.167.33.1
           x30: x80a72101 allowed SURA host 128.167.33.1
           x34: x80a72101 by SURA host 128.167.33.1
           x38: x80a72101 option. SURA host 128.167.33.1

Unfortunately, thats all you get in an IP option.

So, what's going on? For sure, if a packet has to hop around in the
SURA network before it (goes to/comes from) GWU-GATE, its going to take
some time. Maybe get lost? Maybe get duplicated?

What kind of network media/link levels do packets traverse here? I want to
make sure that LANL doesn't acquire (as in purchase) any hardware/protocols
that behave as above. Maybe we already have. Yikes!

Phil Wood (cpw@lanl.gov)



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