infamous ARP cache problem

[kevyn]

Hi there,

running server 2003 with 2 NICS.

NIC 1 - direct connection to DSL modem
NIC 2 - connection to wireless router (the router isnt DHCP enabled)

3 machines log onto the server with manually inputted IP addresses.

The problem i have is that recently my cable modem was changed over, and when i try to establish network connection i get the cannot clear arp cache.

So i have tried clearing the cache using arp -d and then viewing it with arp -a and it says that the cache is empty...which is nice.

I have also run the netsh command just incase.

As soon as i try to repair the connection with the cleared arp cache, i got the same result. Now i read through the forums and took the advice of stopping routing and remote access, which i simply paused in server 03. Now when i came to repair the network connection again, it cleared the cache but only got a limited connection (couldnt access web). I then cleared the cache again with R&RA off, and went through it all again, and turning the modem off etc....but i always get the same result.

How do i get my internet connection back on track!? I presume you can run R&RA again once the cache is cleared and connection esablished?

(the connection works fine when connected to a laptop)

Thank you!!

[Will.Spencer]

You're in a situation where you can't really turn off Routing and Remote Access -- because you're actually using it. The Routing and Remote Access service is what is enabling your two client PC's to connect to the Internet via your Windows server.

The old fashioned way to clear the ARP cache may come in handy in this situation. That is to power everything down and power it all up again. Remember that everything with a TCP/IP stack will have an ARP cache: your modem, your router, your server, and your PC clients.

[kevyn]

Will, i have tried powering everything down for about an hour, then turning the modem on, then powering up the server, and it instantly gets limited or no connection. Sometimes it manages to get a connection without errors - but once again i can't actually get online.

The web still works fine with the laptop when plugged directly into it (and with the same cable and everything)

I can't believe a change of modem has caused so many problems! :evil:

Any other suggestions of how to clear the cache and restore my connection without losing my network with disabling routing&remote access??

*crosses fingers*

[Will.Spencer]

Let me see if I understand what you are saying:

1. When you connect a laptop directly to the modem, the laptop can get online.
2. When you connect your server directly to the modem, that server cannot get online.

Is that correct?

[kevyn]

That is correct Will, indicating that the line and modem, and ethernet cable are all ok! Its just that the server can't get online. The arp cache says it is clear, but as soon as i try to acquire an address, it either

a) limited or no connection (and can't get online) or
b) arp cache needs clearing error.

The only other option that i can see is that the NIC might of been damaged when the modem stopped working?? I don't know if this is a possiblity, as the server seems in perfect working order apart from that?

[Will.Spencer]

I am much more tempted to believe that you are experiencing some sort of bug in Microsoft Windows.

If this is the case, it could be very difficult to track down how Windows has wedged itself.

I would try to add a static ARP entry, although that's far from a certain cure.

ARP -sInetAddr EtherAddr [IfaceAddr] : Adds a static entry to the ARP cache that resolves the IP address InetAddr to the physical address EtherAddr. To add a static ARP cache entry to the table for a specific interface, use the IfaceAddr parameter where IfaceAddr is an IP address assigned to the interface.

You might also try removing all network protocols and drivers and rebooting to auto-rediscover your Ethernet card. That often mysteriously and miraculously clears up hard-to-troubleshoot issues.

Alternatively, Windows really is not the best switch or router. A little LinkSys box might be a much more reliable choice.

[kevyn]

thanks for the tip, i will try the static arp address when i get home.

The other problem i discovered when i got home, was that i remembered that i was infact using a network connection on the motherboard to get the internet into the machine, and then using another stand alone NIC to connect to a wireless router to broadcast the signal!

so im really really hoping that the motherboard hasn't got a problem with it!!

i will let you know how the static arp goes...:???: