VMS and Comcast cable modem

VMS and Comcast cable modem

Post by Gareth V. » Fri, 18 Feb 2005 04:23:55


At home I have a broadband Comcast connection via a cable modem. The
home machine is a PW600au running VMS V7.3-2 and TCPIP V5.4-15: it is
connected to the cable modem via a router (the wife's PC is also
connected to this router via a firewall router). I use my connection
very extensively to SSH to my work machines at all hours, so I leave
the connection on permanently. As is common with ISPs, the IP address
of the home machine is obtained via DHCP.

For the past six weeks, this connection has been uninterrupted (the last
time it was done was when I had to shut the machine down to replace some
faulty memory cards): until four days ago, when my sessions into the work
machines froze. The home machine continued to function:
TCPIP SHOW INTER WE0 showed packets being sent and received, but I could
not type anything into the remote windows and those windows were not
updated. This has now happened about ten times since then. The problem
can be fixed by logging out, logging in as SYSTEM, running TCPIP$SHUTDOWN
and TCPIP$STARTUP, and then logging back in as myself. But this is damn
inconvenient and I'd like to understand what is going wrong before
contacting Comcast, whose technical support staff have a very PC-centric
view of the world.

Two causes spring to mind:

1) My ethernet card is failing. This seems a tad unlikely, as I would
expect to see errors in TCPIP SHOW INTER WE0/FULL and there aren't
any.

2) Comcast has reconfigured something and this is causing the VMS IP
stack to "get confused". A quick comparison of TCPIP SHOW NAME
output on a work and home machine shows a subtle difference:

a) work machine output

$ tcpip show name

BIND Resolver Parameters

Local domain: cfa.harvard.edu

System

State: Started, Enabled

Transport: UDP
Domain: cfa.harvard.edu
Retry: 4
Timeout: 4
Servers: 131.142.10.1, 128.103.200.101
Path: No values defined

b) home machine output

$ tcpip show name

BIND Resolver Parameters

Local domain: hsd1.ma.comcast.net

System

State: Started, Enabled

Transport: UDP
Domain: hsd1.ma.comcast.net.
Retry: 4
Timeout: 4
Servers: 204.127.202.19, 216.148.227.204
Path: hsd1.ma.comcast.net.

Note the full stop (periods) at the end of Domain: and Path: Is this
punctuation valid? I note that the domain name now displayed is
different from what I remember it being in the past.

So my questions are:

1) Is the BIND output a clue to the cause?

2) Is anyone else in the Boston area with a Comcast cable modem also
experiencing connectivity problems?

Gareth

--
------------------------------------------------------------------------
Gareth V. Williams, MS 18, 60 Garden Street, Cambridge, MA 02138, U.S.A.
Associate Director, IAU Minor Planet Center
XXXX@XXXXX.COM http://www.yqcomputer.com/
OpenVMS & RISC OS: refined choices in operating systems
 
 
 

VMS and Comcast cable modem

Post by hamilto » Fri, 18 Feb 2005 05:18:38

In article < XXXX@XXXXX.COM >, "Gareth V. Williams" < XXXX@XXXXX.COM > writes:
!snip of problem explication!
!2) Comcast has reconfigured something and this is causing the VMS IP
! stack to "get confused". A quick comparison of TCPIP SHOW NAME
! output on a work and home machine shows a subtle difference:
!
! a) work machine output
!
! $ tcpip show name
!
! BIND Resolver Parameters
!
! Local domain: xxx.harvard.edu
!
! System
!
! State: Started, Enabled
!
! Transport: UDP
! Domain: xxx.harvard.edu
! Retry: 4
! Timeout: 4
! Servers: xxx.xxx.xx.x, xxx.xxx.xxx.xxx
! Path: No values defined
!
! b) home machine output
!
! $ tcpip show name
!
! BIND Resolver Parameters
!
! Local domain: xxxx.xx.comcast.net
!
! System
!
! State: Started, Enabled
!
! Transport: UDP
! Domain: xxxx.xx.comcast.net.
! Retry: 4
! Timeout: 4
! Servers: xxx.xxx.xxx.xx, xxx.xxx.xxx.xxx
! Path: xxxx.xx.comcast.net.
!
! Note the full stop (periods) at the end of Domain: and Path: Is this
!punctuation valid? I note that the domain name now displayed is
!different from what I remember it being in the past.
!
!So my questions are:
!
!1) Is the BIND output a clue to the cause?
!

I am using TCPware as my IP stack. From what I remember of TCP/IP Services, the
BIND output looks a little odd. I'm used to seeing "No values defined" as a
proper "value" for Path:. The domain value looks a little odd, too. The
trailing "." may be incorrect, as well as the naming information _before_
"comcast.net". BTW, my bind server/domain information points to my firewall,
not the "outside". My firewall's bind server/domain information points to the
"outside".

!2) Is anyone else in the Boston area with a Comcast cable modem also
! experiencing connectivity problems?
!

I'm not experiencing any problems with Comcast in the Boston area, nor have I
in the 3+ years that I've used a VMS machine from home.

 
 
 

VMS and Comcast cable modem

Post by Gareth V. » Fri, 18 Feb 2005 06:38:01


: connected to the cable modem via a router (the wife's PC is also
: connected to this router via a firewall router). I use my connection

Terminology snafu. Should have read "connected to the cable modem via
an ethernet switch (the wife's PC is also connected this switch via
a firewall router)."

I've received a number of e-mail responses, I will do some follow-up
by e-mail.

Gareth

--
------------------------------------------------------------------------
Gareth V. Williams, MS 18, 60 Garden Street, Cambridge, MA 02138, U.S.A.
Associate Director, IAU Minor Planet Center
XXXX@XXXXX.COM http://www.yqcomputer.com/
OpenVMS & RISC OS: refined choices in operating systems
 
 
 

VMS and Comcast cable modem

Post by John Gemig » Fri, 18 Feb 2005 06:53:41

"Gareth V. Williams" < XXXX@XXXXX.COM > wrote in message
news: XXXX@XXXXX.COM ...

I was having similar problems with Adelphia when they changed their lease
times to 3 hours (and sometimes less). I would also lose telnet and ssh
sessions from my pc and/or laptop.

-John


 
 
 

VMS and Comcast cable modem

Post by David J Da » Fri, 18 Feb 2005 12:31:57


Well, either way, you'll want to make sure that the firewall/router is
between the cable modem and the switch. No system should be exposed
directly to the internet without a valid reason, IMO.

Cable Modem ---- Router/Firewall ---- Switch ---- Computer(s)

--
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dba DJE Systems
http://www.yqcomputer.com/

Unofficial OpenVMS Hobbyist Support Page:
http://www.yqcomputer.com/

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VMS and Comcast cable modem

Post by koehle » Fri, 18 Feb 2005 23:09:01

In article < XXXX@XXXXX.COM >, "Gareth V. Williams" < XXXX@XXXXX.COM > writes:


I've had SSH implementations just up and croak every now and then.
I thought it was a bug in PuTTY, but it may be more common. I've
seen it between machines at home conected by a swithing hub, and
machines at different work sites connected via different ISPs.