Unstable network

[electraboy]

Recently, i re-installed my server at home (1 win2kAS server with 4-5 XP clients) and since then my network is very unstable.
When i want to copy a file that is larger than 50 Meg, i get an error saying the network resource is no longer available, although i'm still connected with the server trough a terminal server and mail.
I get this msg only when i launch the copy from a workstation, not when i launch it from the server.
The error delayed write failed probably has something to do with the situation too, but even microsoft doesn't offer a solution which i haven't applied yet.
A friend told me to look at the MTU size in the registry, but i have no idea what its size should be.

Can anyone give me some advice on this please ? It is impossible to make anything foolproof because fools are so ingenious.

Murphy's Laws​

 

[Ntr0P]

If the server and workstations are on the same Ethernet segment, the MTU is 1500. This is the default setting and unless you deliberately changed it, it is fine. If you are connecting to a service via WAN link (and depending on the link), the MTU may be different.

 

[electraboy]

I defined the MTU recently (about two weeks ago) at 1500, but nothing seems to have changed (and shouldn't then).
So what else can i check ? It is impossible to make anything foolproof because fools are so ingenious.

Murphy's Laws​

 

[DuMan]

What type of device are you using to connect your network? Hub or switch. See if you can change the MTU size on interfaces of that device.

 

[Ntr0P]

I doubt you have an MTU issue, but you can verify the MTU by doing the following:

Run a ping to the location you are connecting to and use the -f and -l switches. -f will prevent the packet from fragmenting and -l allows you to set the packet size. Ping the destination starting with a -l of 1472 (leave 28 for headers - so 1472 + 28 = 1500). Keep moving down until you have a successful ping. If your MTU is 1500 the first ping of 1472 should work.

Example:
ping -f -l 1472 xxx.xxx.xxx.xxx

 

[electraboy]

I'm using a switch (10/100) on which i cannot set anything (but works fine).
I don't think it's an hardware problem, because the same configuration has been working fine before (with W2KAS too).

NTrOP, i can ping every location without any loss (haven't tried your switches, but would it make any difference ?) It is impossible to make anything foolproof because fools are so ingenious.

Murphy's Laws​

 

[Ntr0P]

The switches definitely make a difference if you are determining the MTU. If your MTU is too high, the packets will fragment and still be sent so you won't notice the issue. The -f switch will prevent fragmentation.

 

[electraboy]

I tried this and the packets are succesfully send when i try a size 1472 or smaller.
When i use i.e. 1473 its says, packets cannot e fragmented (like it should i guess). It mentions also smthing about DF is set ??
The problem about my networkproblem still exists It is impossible to make anything foolproof because fools are so ingenious.

Murphy's Laws​

 

[Ntr0P]

You just ruled out MTU though. Your MTU is 1500. Anything less than that is fine as well (1500 is optimal though).

 

[electraboy]

At the company we experienced networkproblems too while we were migrating from Token Ring to Ethernet. The problems were caused by a router that hadn't initialized the switches in a right manner (wrong IP-adresses or something).
At home my PDC is my router. Could misconfiguration from the router led to the above problems ?
It is impossible to make anything foolproof because fools are so ingenious.

Murphy's Laws​

 

[Ntr0P]

A mis-configured router can certainly cause problems especially if it is load balancing across more than one route. If you were performing round-robin load balancing over two routes where only one of which was valid, you would see 50% packet loss.

So you have 1 server at home and multiple clients. Is this a multi-homed server? MS isn't real good about routing packets out the correct interface unless specifically defined in the route table.

 

[electraboy]

What is a multi-homed server ?
(The fact that i should ask the question implies maybe i haven't got one ?) It is impossible to make anything foolproof because fools are so ingenious.

Murphy's Laws​

 

[Ntr0P]

Multi-homed - more than one network card.

 

[electraboy]

Ah, OK.
Wel yes, it's a multihomed server.
How should i define the correct interface in the route table ? It is impossible to make anything foolproof because fools are so ingenious.

Murphy's Laws​

 

[Ntr0P]

You will want to add the routes to the various networks so they travel out the appropriate interface. Examples below of two networks: 1) 192.168.100.0/24 and the other 192.168.200.0/24. The commands to add the routes from the command prompt would be as follows:

route add 192.168.100.0 mask 255.255.255.0 <gateway IP for this subnet 192.168.100.???>

route add 192.168.200.0 mask 255.255.255.0 <gateway IP for this subnet 192.168.200.???>

You can type 'route' at the command prompt for more detailed instructions.