Advice on troubleshooting W2K routing
Jim Smith
OS specific, but dis.nt seems to be dead. Also although this is a home
network, it probably isn't a typical home network. Advice on other
better groups is welcome)
I am having serious problems with the routing between my internal
network and the Internet and need some advice on troubleshooting.
My set up is as follows.
I have a W2K server with a cable modem and an ISDN card. I have a number
of other machines on an Ethernet network (W2K Professional and Linux)
which use the W2K server as a gateway.
The cable modem appears to W2K as an Ethernet port and gets its IP
configuration, including default gateway and DNS servers via DHCP from
the cable provider. I have set up network address translation on the
W2K machine and set the default gateway on the other machines to the W2K
machine.
This all worked perfectly until the other day when I tried to set up a
demand-dial interface on ISDN so I could collect mail and news from my
ISP (Demon) using dial-up (you have to dial-up to demon to use their
mail and news). This seemed to work initially but then started to fail
intermittently. I took out the demand dial interface, but the problems
persisted.
The situation now is that external connectivity from any of my
workstations is up and down like a yo-yo. The situation can change from
second to second but as far as I can tell, by turning round and doing
the same thing on the gateway machine, the problem is internal rather
than external (although of course by the time I turn round the situation
may have changed).
I have a number of ideas about possible causes, but am at a loss on how
to investigate further. I need some guidance on tools and techniques to
try to pin it down.
One potential problem is either the reliability of, or routing to, my
providers DNS servers. Is there a set of alternative DNS servers I can
use to help distinguish? Can I use demon DNS servers when not dialled up
to demon?
How can I pin down the routing problem to internal or external?
If it is internal how can I diagnose the cause in the W2K server?
--
Jim Smith
Kenny
1) Can you give the ISDN connection a higher (such as 2) 'metric' value than
the cable modem connection (such as 1)?
2) You shouldn't really have a default gateway defined on the NIC connected
to the cable modem.
3) Perhaps run the route command and post the routing table!?!
4) Is Win2k box a multihomed jobbie?
"Jim Smith" <j...@jimsmith.demon.co.uk> wrote in message
news:BRrxlpGi$M97...@jimsmith.demon.co.uk...
Jim Smith
<k.wa...@clinicare.co.uk> writes
>Couple of questions/pointers
>
>1) Can you give the ISDN connection a higher (such as 2) 'metric' value than
>the cable modem connection (such as 1)?
The ISDN connection isn't active at the moment.
>2) You shouldn't really have a default gateway defined on the NIC connected
>to the cable modem.
I don't. The default gateway is set by DHCP from NTL. ( The modem is
connected through USB, but appears to W2K as a NIC. )
>3) Perhaps run the route command and post the routing table!?!
Routing table for the gateway box. (with some addresses changed for
security purposes)
========================================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 ntl.net.work.254 cablemodem 1
10.0.0.0 255.0.0.0 ethernet ethernet 1
ethernet 255.255.255.255 127.0.0.1 127.0.0.1 1
10.255.255.255 255.255.255.255 ethernet ethernet 1
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
ntl.net.work.0 255.255.255.0 cablemodem cablemodem 1
cablemodem 255.255.255.255 127.0.0.1 127.0.0.1 1
ntl.net.work.255 255.255.255.255 cablemodem cablemodem 1
224.0.0.0 224.0.0.0 ethernet ethernet 1
224.0.0.0 224.0.0.0 cablemodem cablemodem 1
255.255.255.255 255.255.255.255 cablemodem cablemodem 1
Default Gateway: ntl.net.work.254
========================================================================
Persistent Routes:
None
Routing table from a Linux system
10.0.0.0 * 255.0.0.0 U 0 0 0 eth0
127.0.0.0 * 255.0.0.0 U 0 0 0 lo
default W2K machine 0.0.0.0 UG 0 0 0 eth0
>4) Is Win2k box a multihomed jobbie?
Yes. Ethernet connection to the internal network, Cable modem to the
Internet (and once, ISDN to the Internet)
--
Jim Smith
David Wood
<j...@jimsmith.demon.co.uk> writes
>I have a W2K server with a cable modem and an ISDN card. I have a
>number of other machines on an Ethernet network (W2K Professional and
>Linux) which use the W2K server as a gateway.
>
>The cable modem appears to W2K as an Ethernet port and gets its IP
>configuration, including default gateway and DNS servers via DHCP from
>the cable provider. I have set up network address translation on the
>W2K machine and set the default gateway on the other machines to the
>W2K machine.
To be honest, I'd use the Linux box to do the NAT rather than W2K Server
- but that's your choice. I think you're going to get finer control
using the Linux box, and I think you may need that control here, though,
to be fair, I have never set up a Linux box as a router.
>This all worked perfectly until the other day when I tried to set up a
>demand-dial interface on ISDN so I could collect mail and news from my
>ISP (Demon) using dial-up (you have to dial-up to demon to use their
>mail and news).
No - you don't. You can collect mail from Demon using POP3 from any ISP,
though you will have to set your POP3 password at
<https://www.password.uk.demon.net> first.
Demon's news server is nothing special, though, to be fair, neither is
ntl:'s. Also ntl:'s SMTP smart host has been playing up recently - see
ntl.support.broadband.cm passim. I avoid the lot and use machines at
gradwell.com - but that's an option that costs money.
I'm bemused as to how you set up a dial on demand interface to Demon in
the situation when you want the majority of your ISP traffic to go over
ntl: - unless, of course, W2K Server has some feature that I've
forgotten about. I know the networking features in W2K Server are more
capable than W2K Professional - I only regularly use Professional.
>This seemed to work initially but then started to fail intermittently.
>I took out the demand dial interface, but the problems persisted.
It sounds like you've got a default gateway problem. Assuming you want
the bulk of your network traffic to go via the cable modem you do want
the default gateway set by DHCP on the cable modem (I don't understand
the other poster's advice here).
The problem is how do you install the routes to Demon's network. From
memory, you can either have "Use default gateway on remote network"
(connection properties, Networking tab, TCP/IP, Properties button,
Advanced... button, General tab) checked or not. I'm pretty sure W2K
Server is similar to the W2K Professional machine that I'm looking at.
If that button is checked, then a default route will be installed to the
default gateway at Demon, and this is done in such a way that it has
higher priority (lower metric) than the default gateway on any of your
LAN cards (including the USB connected cable modem).
If that button is not checked, then the connection will basically not be
used - from memory, you get a route to whatever subnet is defined by the
IP address and netmask returned by the PPP negotiation. You'll need to
install further routes so that traffic to Demon's machines to get any
useful traffic over the dial up link. Unless W2K Server has extra
features over W2K Professional that I've forgotten about, the only way I
can think of this is static routes pointing at the interface number of
the dial-up adapter - though I'd expect this will foul up the dial on
demand. It's for this reason I was thinking of using the Linux box - you
should have the route commands in a shell script for use when the ISDN
connection is brought up.
>The situation now is that external connectivity from any of my
>workstations is up and down like a yo-yo. The situation can change
>from second to second but as far as I can tell, by turning round and
>doing the same thing on the gateway machine, the problem is internal
>rather than external (although of course by the time I turn round the
>situation may have changed).
Are you absolutely sure that the dial on demand has been disabled? If
your default gateway keeps getting changed, that could cause this
symptom. Further, I'm not sure how well the NAT functions in W2K Server
cope with being used in this kind of scenario, because I've never used
them like this.
I use hardware routers - a Netgear RO318 on the cable modem and a 3Com
OfficeConnect Remote 511s on the ISDN side. However, I've now got
everything I need operating over the cable modem and the ISDN router is
sat in the junk box. Certainly a box like the 3Com on your LAN should
solve at least the ISDN side of the problem - not least because it can
advertise the routes it has available via ISDN using RIP, and that works
fine with W2K's RIP listener.
>I have a number of ideas about possible causes, but am at a loss on how
>to investigate further. I need some guidance on tools and techniques to
>try to pin it down.
I'd guess a combination of "route print" on the gateway machine coupled
with judicious use of ping or tracert to various external machines will
show what's happening on the gateway machine. Once you understand the
behaviour there, you can then start wondering about what's happening to
the other machines on the LAN.
>One potential problem is either the reliability of, or routing to, my
>providers DNS servers. Is there a set of alternative DNS servers I can
>use to help distinguish? Can I use demon DNS servers when not dialled
>up to demon?
You can, though I'm bemused as to why you think DNS servers are part of
the problem. ntl:'s DNS servers have been a bit troublesome - but I
can't see how this would explain the problems you're talking about.
Failure to resolve names to IP addresses - yes - that's a DNS problem
for sure.
>How can I pin down the routing problem to internal or external?
>
>If it is internal how can I diagnose the cause in the W2K server?
As you can tell, my expertise with RRAS (the NAT functions) and dial on
demand in W2K Server is almost nil, and I know it's different to W2K
Professional - but I hope there's some pointers here.
David
--
David Wood
da...@wood2.org.uk
John Underwood
(Reference: <IkFd6esM...@wood2.org.uk>)
>Demon's news server is nothing special, though, to be fair, neither is
>ntl:'s. Also ntl:'s SMTP smart host has been playing up recently - see
>ntl.support.broadband.cm passim. I avoid the lot and use machines at
>gradwell.com - but that's an option that costs money.
If a more limited, but free, service would be acceptable, it is worth
having a look at http://www.cis.dfn.de who provide a free news server
available from anywhere. You have to register and agree to their
conditions and receive a login and password. The carry no binary groups
and only a few alt.*. They do, however, carry most of the uk.*
hierarchy. In most groups, binaries and html are removed.
--
John Underwood
Use the Reply To: address for the next 30 days
After that write to jo...@the-underwoods.org.uk
Do not send anything to the From: address
Jim Smith
<da...@wood2.org.uk> writes
>In message <BRrxlpGi$M97...@jimsmith.demon.co.uk>, Jim Smith
><j...@jimsmith.demon.co.uk> writes
>>I have a W2K server with a cable modem and an ISDN card. I have a
>>number of other machines on an Ethernet network (W2K Professional and
>>Linux) which use the W2K server as a gateway.
>To be honest, I'd use the Linux box to do the NAT rather than W2K
>Server - but that's your choice. I think you're going to get finer
>control using the Linux box, and I think you may need that control
>here, though, to be fair, I have never set up a Linux box as a router.
If I had a choice I would use Linux, but I don't have Linux drivers for
my cable modem.
>
>
>>This all worked perfectly until the other day when I tried to set up a
>>demand-dial interface on ISDN so I could collect mail and news from my
>>ISP (Demon) using dial-up (you have to dial-up to demon to use their
>>mail and news).
>
>No - you don't. You can collect mail from Demon using POP3 from any
>ISP, though you will have to set your POP3 password at
><https://www.password.uk.demon.net> first.
You do if you want to send mail. I already use pop3 for collection.
>Demon's news server is nothing special, though, to be fair, neither is
>ntl:'s. Also ntl:'s SMTP smart host has been playing up recently - see
>ntl.support.broadband.cm passim. I avoid the lot and use machines at
>gradwell.com - but that's an option that costs money.
I don't have any access to NTL's servers, the cable modem is a trial of
a pure connectivity service. Because it is a trial, I don't want to give
up my demon service just yet. If ever (my web site such as it is there).
>
>I'm bemused as to how you set up a dial on demand interface to Demon in
>the situation when you want the majority of your ISP traffic to go over
>ntl: - unless, of course, W2K Server has some feature that I've
>forgotten about. I know the networking features in W2K Server are more
>capable than W2K Professional - I only regularly use Professional.
>
>
>>This seemed to work initially but then started to fail intermittently.
>>I took out the demand dial interface, but the problems persisted.
>
>It sounds like you've got a default gateway problem. Assuming you want
>the bulk of your network traffic to go via the cable modem you do want
>the default gateway set by DHCP on the cable modem (I don't understand
>the other poster's advice here).
>
>
>The problem is how do you install the routes to Demon's network. From
<snip>
>the only way I can think of this is static routes pointing at the
>interface number of the dial-up adapter - though I'd expect this will
>foul up the dial on demand.
This is what I tried, but it didn't work. It wouldn't let me set them
up when the PPP interface wasn't active and if I set them up while
dialled up they disappeared.
>
>
>>The situation now is that external connectivity from any of my
>>workstations is up and down like a yo-yo. The situation can change
>>from second to second but as far as I can tell, by turning round and
>>doing the same thing on the gateway machine, the problem is internal
>>rather than external (although of course by the time I turn round the
>>situation may have changed).
>
>
>I use hardware routers - a Netgear RO318 on the cable modem and a 3Com
>OfficeConnect Remote 511s on the ISDN side. However, I've now got
>everything I need operating over the cable modem and the ISDN router is
>sat in the junk box. Certainly a box like the 3Com on your LAN should
>solve at least the ISDN side of the problem - not least because it can
>advertise the routes it has available via ISDN using RIP, and that
>works fine with W2K's RIP listener.
What sort of cost are we talking about?
>
>
>>One potential problem is either the reliability of, or routing to, my
>>providers DNS servers.
>
<snip>
> though I'm bemused as to why you think DNS servers are part of the
>problem.
I lot of the problem is with Web browsing which is heavily reliant on
DNS. If the DNS is coming and going it would explain the browser
behaviour. I don't really think they are the real cause of the problem
but you have to eliminate everything.
>
>
>
>David
--
Jim Smith