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From: malis@BBN.COM (Andy Malis)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: PSN Questions
Message-ID: <9102271500.AA29081@ucbvax.Berkeley.EDU>
Date: 27 Feb 91 13:53:14 GMT
References: <9102260055.AA03710@nswc-wo.navy.mil>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 36

Donnie,

> 1) Is there a limitation to the number of virtual circuits that
>    a PSN will allow a particular host for X.25 Standard
>    connections?  I need 64.

Depending on the model PSN, 400 or 1200 (or possibly fewer,
depending on your host's particular port configuration).

> 2) What are the chances (slim,  probably,  definitely) that I
>    can always get up to 64 virtual circuits when my host
>    requests them?

The C/300 PSN can support 1200 simultaneous VCs for all of its
hosts, and the C/30 PSN can support 400.  Individual hosts can
also be limited by configuration to a fewer number of VCs,
although that is not, to my knowledge, common practice on the
MILNET.  On a C/300 PSN, for all practical purposes, your host
should have no problem getting 64 VCs whenever it needs them.  On
a C/30 PSN, it becomes more dependent upon what the other hosts
on the PSN are also doing at the same time.  

> 3) Will a PSN close a virtual circuit which has been idle for a
>    period of time?  If so, what is the timer value in the PSN?

Yes.  The MILNET uses a timer value of 3 minutes.

If you are not sure what model PSN you are using, or have any
problems using the MILNET, I suggest calling the CONUS MILNET
Monitoring Center at (800) 451-7413, or (703) 692-5726 or
692-2268.  They can also be reached by email at
DCA-MMC@DCA-EMS.DCA.MIL .

Regards,
Andy Malis
BBN Communications