Networking assistance - TCP / IP - Resolved

[Pixelfill]

I know we have some accomplished networking geniuses on here, and I hope one or two of you might be able to help me out.

 

I've been trying to get a machine at work to perform some very simple networking, and I'm absolutely baffled, both are XP service pack 2.

 

It's connected to another machine by a Cat 5e patch cable, (a crossover cable doesn't help before anyone suggests it ).

 

I've set the IP addresses for both machines in the 192.168.0.x range, and set the netmasks to 255.255.255.0. Now here's where it starts to get interesting.

 

I tried to ping from one machine to the other, and get "request timed out." So I check the firewalls on both machines, they are both disabled. I installed Wire shark on both machines and check what's going on.

 

The first (problematic) machine keeps sending an ARP request to the network, and get's no response. checking the destination machine it's receiving the ARP request and responding to the source identifying itself, but it seems not to be getting through.

 

Okay so I set up a static entry into the ARP table on the first machine, and try pinging again. this time the first machine is sending the ICMP packet, but still request time out. checking the destination machine using Wireshark, the ICMP ping is received and the response is sent, but it's not getting through.

 

Trying the other way round (from dest to first), the ping request never makes it to the first machine

 

The cable has been tested between a different first machine (different spec) and the same destination machine, and as you would expect there is no issue at all.

 

So I hear you saying dead network on the first machine , however I can reproduce this on another machine of the same spec, and on both network ports of each .

 

The machines in question are built around a PICMG based ROBO-8713BVG2 SBC, from what I can tell the ethernet controller uses the Realtek 811x chipset, and I've tried 3-4 drivers to no avail.

 

Help please anyone able to give me any pointers as to what I might have overlooked.

 

Thanks

 

Mike

[JohnH]

been a long time since i messed with networking and xp but have you tried leaving it as a dynamic IP and let it try and work itself out?

[Pete]

Try http://support.microsoft.com/kb/299357 ?

 

Try Repair network option no the machines?

 

How come you're doing a direct connect anyway?

[Pixelfill]

Unfortunately it's just 2 machines with a direct cable connection, so no DHCP options, they just sit there dumbly trying to obtain an IP address, but there's no-one to allocate them one Thanks though.

[Pixelfill]

Try http://support.microsoft.com/kb/299357 ?

 

Try Repair network option no the machines?

 

How come you're doing a direct connect anyway?

 

I'll give that KB article a try tomorrow cheers Pete.

 

I tried repair on both, but it didn't work:(

 

We are using a proprietary UDP link to transfer realtime data from one machine to another. Well we want to anyway.

 

Mike

[Pete]

Although you've tested the cable - try another anyway

I've had cables half work before.

[ShamelessTT]

Same workgroup?

[JustGav]

Might not be anything, but I remember the older intel network cards used to have an issue with auto-neg, turn that off and see if it makes any difference. I'm guessing you don't have a spare hub or something?

 

Just spotted they are also gig cards, Did you only swop over 1/2 3/6 perhaps. Gig uses all 8 cables....

 

Try this

http://logout.sh/computers/net/gigabit/

[Pixelfill]

Cheers Gav, We've got a spare 10/100 Hub if necessary, but would prefer not too, trying to keep latency to the very minimum.

 

This is one thing that occured to me as well, I've had problems with auto neg on an Intel server adaptor, the destination is an Intel adaptor but it's currently setting to Auto detect. I also checked to make sure that Jumbo packets were disabled.

 

Is there a possibility that the Realtek advanced settings might not match the Intel settings on the other machine?

 

 

edit: ooo the crossover wiring could be a possibility, I did wonder whether the other machines which work might have the automdix functionality and this machine wouldn't, do both ends need auto-mdix to work with a straight cable? The crossover I tried is quite likely to be a cat5 (2 pairs) crossover rather than a Gb cable, we could have a winner here

 

Mike

[JustGav]

Cheers Gav, We've got a spare 10/100 Hub if necessary, but would prefer not too, trying to keep latency to the very minimum.

 

This is one thing that occured to me as well, I've had problems with auto neg on an Intel server adaptor, the destination is an Intel adaptor but it's currently setting to Auto detect. I also checked to make sure that Jumbo packets were disabled.

 

Is there a possibility that the Realtek advanced settings might not match the Intel settings on the other machine?

 

Mike

 

Forcing the auto neg would definitely help, but unless you have a full gig crossover cable it will have issues anyway. Get those crimpers out

[Pixelfill]

Same workgroup?

 

yes

[Pixelfill]

Forcing the auto neg would definitely help, but unless you have a full gig crossover cable it will have issues anyway. Get those crimpers out

 

Thanks - will give it a try

 

Mike

[DamanC]

Plug it all into a hub/switch.

[kill1308]

Cat5e supports Gigabit.

 

You could try fixing the speed to 100mbit/Full Duplex on both adapters to see if that works (which a standard Cat5 cable will support)

 

If you've got them both set to 192.168.0.xxx and in the same subnet, communication should be no problem if the firewalls are turned off (provided both network cards are of course working correctly). It's either firewall (which you've proved is not the case) or cabling issue...

 

Have the machines ever been on any other network just out of curiosity?

[Pixelfill]

I don't believe they've been on another network. But I'm interested where that thought would lead you nonetheless.

 

 

Mike

[DamanC]

Oh, just thought, do they ping themselves Mike?

[kill1308]

Also you should be able to use a standard network cable, there's no need for a crossover cable. I'd recommend a Cat6 cable if it's in a harsh environment or travelling any kind of distance.

 

Another bit of troubleshooting to look at... If you are using a cat5 crossover I'd imagine it will try and auto-negotiate to 100mbit which if any of the cards are set to a fixed speed other than 100mbit, chances are you'll have a problem.

 

Get a standard Cat5e or Cat6 cable and I think you'll be in business

[kill1308]

I don't believe they've been on another network. But I'm interested where that thought would lead you nonetheless.

 

 

Mike

 

Ignore that, I was wondering if there could have been any other entries in dns resolver cache, but then I realised you were trying to communicate by IP and not hostname (sorry half asleep lol)

[Pixelfill]

Oh, just thought, do they ping themselves Mike?

 

Yes they do

 

Mike

[Konrad]

Did you switch off Windows Firewall only or you switched off firewall on connection too? Sometimes even if Windows Firewall is switched off connection itself is still firewalled, you need to go to Network Connections and check it. I'm also prety sure you NEED crossover cable when not using hub.

[Pixelfill]

Did you switch off Windows Firewall only or you switched off firewall on connection too? Sometimes even if Windows Firewall is switched off connection itself is still firewalled, you need to go to Network Connections and check it. I'm also prety sure you NEED crossover cable when not using hub.

 

Yeah thanks Konrad, I've been caught out by that in the past, the firewall is disabled for each connection. I'm definitely going to try the crossover cable tomorrow.

 

Mike

[kill1308]

I'm also prety sure you NEED crossover cable when not using hub.

 

You're right, you do if you are using a 10/100 card, two 10/100/1000 cards won't need a crossover cable. Gigabit links are bi-directional and use all 4 pairs whereas 10/100 only uses 2 of the pairs, one to transmit the data, and the other to receive. The reason you use a crossover cable on a 10/100 card is to do as the cable suggest, crossover the transmit/receive pairs to each computer.

[SaqTRD]

hi,

 

Just a thought, if you go into Network connections via the control panel on both machines, you dont have any additional connections do you, eg. if someones tried to setup a virtual machine, it might have a network bridge on one of the machines which tends to bugger things up.

 

Also whats the connection status on both adapters whilst the network cables are plugged in?

 

Saq

[Pixelfill]

hi,

 

Just a thought, if you go into Network connections via the control panel on both machines, you dont have any additional connections do you, eg. if someones tried to setup a virtual machine, it might have a network bridge on one of the machines which tends to bugger things up.

 

Also whats the connection status on both adapters whilst the network cables are plugged in?

 

Saq

Nope, both are pretty vanilla OS installs, no vrtual machines, no bridged connections, when physically connected both machines show that they are connected, and report 1000Mbps connection, as I said above it all works aside from the receive leg of one connection.

 

I appreciate all the suggestions though guys.

 

Mike

[Wez]

Sounds like a duplex feckup of some description, for testing I would knock them down to either 100mb or 10mb half duplex.

 

I take it when connected directly together you are using a Xover cable, I know newer switch gear can auto switch to the correct mode, not seen a network card that does it yet, not saying there arent any out there though.

 

As for DHCP without a DHCP server XP will sort itself out and they would work, XP allocates a default private range when a DHCP server cannot be found