1 router 2 nics wont work

MediaMan

This is a head scratcher.

SMC 7004AWBR wireless router. Has worked through countless installs and hooking countless other PCs up to it. (hard wired) Here's the quirk that's just popped up. PC 1 hooked up. Internet OK. PC 2 hooks up and the NIC in PC2 fights for the connection. It establishes...drops...establishes drops repeatedly every few seconds.

Unplug PC1 and PC2 gets the connection. Plug PC2 back in and PC1 takes the connection away from PC2.

/me scratching head

Router settings are correct. MAC addressing set up correctly. DHCP enabled. Even tried resetting router back to factory defaults and taking away all protection protocols. Same thing.

The variable. I'm using a new xp install disc. Could it be that one WinXP installation sees the other computer and there's some sort of conflict? Two different install discs with two different numbers.

Anyway...head scratcher #2

DOS Command window commands have gone buh bye. Ipconfig returns "IPCONFIG IS NOT RECOGNIZED AS AN INTERNAL OR EXTERNAL COMMAND, OPERABLE PROGRAM OR BATCH FILE"

Searched it out. Found a couple of fixes. Fixes showed nothing broken. Fixed anyway...same result.

I wonder if there is a new reg spyware out that fubars something or corrupts the TCIP stack. Hijack shows clean.

Any help/guesses would be appreciated.

bothered

I have two PCs networked through a Linksys router. I'm not using any NICs though, onboard LAN. Both are using 'differant' xp installs ,one with SP1 and one without and have no problem at all. When I have had problems with it its usualy been because of Zone Alarm or other firewall messing about.

MediaMan

Tis definitely odd. I correct myself. 2 different onboard LANs. This is the first time this has cropped up. I wonder if my ISP is somehow blocking. Course..how would they see through the router to the two different boxes.

Dunno

mmonnin

The ISP should see one MAC address, the router's, so I dont think that should be a problem.

MediaMan

That's what has got me so confused. Up until this moment it's worked just fine. Again...the variable is that install disc. I know that two OS's with the same serial can install on two different PCs...no problems.

It just started. The LANs are fighting each other over the router. Strange. One or the other can work but not both through the router. Same hardware I've used before.

mmonnin

I know why.....




The computers want to Fold. Yes thats It! The solution to all computer problems.:D:D

Thrax

If ipconfig doesn't work by delivering the command from the DOS shell, it's more than likely that your environment variables have been modified.

Environment variables, for those who don't know, is a listing of directories for windows in which any executable can be executed from any command prompt on the system. You could type "ping" from any directory or any drive on your PC, and it would work because that executable is in the c:\winnt\system32 environment variable. That's one of the few defaults for windows EVs.

Correct it in this manner:

1. Right click on my computer
2. Hit properties
3. Clicked the advanced tab
4. Hit environment variables
5. In the "System variables" section at the bottom of the window, scroll to "Path."
6. Double click on path
7. Make SURE that these entries are there:

%SystemRoot%\system32;
%SystemRoot%;
%SystemRoot%\System32\Wbem;

And if they are, and it's STILL not functioning, add these after the last entry:

C:\winnt; (OR) c:\windows; (It depends on your install dir)

and

c:\winnt\system32; (OR) c:\windows\system32;


That will correct ipconfig not working from shell.

MediaMan

Thanks Thrax,

Didn't know about that place to look. Apparently a "optiimising tool" that I found must have been the culprit. I ghosted back my drives to an earlier stage and the dos shell is now working.

Still the two computers won't share the same router. It's an odd problem. PC1...works fine by itself. PC2...works fine by itself...plug PC1 and 2 in and PC2 gets blocked/kicked out/stuffed. Unplug PC1 and PC2 finds the connection and works...vice versa.

This has happened on three different PCs just recently. Each with different OS installs. For the last 2 years...not a problem. I wonder if my ISP, unknown to me, has some way of seeing through the router and denying two connections simultaneously. It's like it only wants one computer connected at any given time.

Odd.

Straight_Man

Guesses as to other ways this can happen, just for you and others (happy you got it fixed, MM):

There are two ways this can happen at the modem:

Especially with DSL, many of the motorola and some of the other modems are also single port SNMP managed routers. To get a LAN to multiconnect, the router behind the router modem needs to masq to mirror the settings of the modem. Process from modem to modem varies too much, but in essence the router needs to accept DHCP from modem and be programmed with FQDN (fully Qualified Domain Name) that the router\modem has. This will be a limited bandwidth connect, but will allow for multiple boxes to access web at once.

The modem can also be set to disconnect from DSL if more than one box tries to connect, this is done with SNMP most often. Fix is same, put a LAN\WAN router behind the modem, mirror router to modem as far as device ID including MAC, and FQDN. Easiest way to do this is to use winipcfg or ipconfig, grab the info from just one box, grab the NIC MAC from any of several programs or from using the /all switch when calling the ipconfig program in XP or 2000 or pressing the All or More Info button after running winipcfg from start|run in Me and back through 98.

To be honest, I worked with my ISP to do this on Cable, they know I have a small LAN and precisely why and that I have a router and do not serve from here (in my sase I told them what I do with that LAN, that I use the router as firewall, had a rep test to confirm that ICMP Echo was supposed to FAIL on this connect. I accept the total bandwidth cap on how fast things can flow overall into my Lan from web, and that is in my customer support record as an acceptance statement. In return, they feed me router-grade DHCP and know my router is masqed. They also know SNMP is off on my router, I told them that and they test the connect for server ports being open at my end now and then at random. I recommend this approach, you will get one heck of a lot less hassles from your ISP if you are open about this.

In MM's case this was software, but this 'one box only can connect' can happen with a router that does not masq also and is also in SNMP mode and it can happen on cable also.

MediaMan

Thanks John,

Gives me clues where to look. Odd how this just started happening after such a long time. The router does use MAC clone so the modem should only be seeing what it thinks is one PC.

/me scratches head more.

Straight_Man

ISP gateways are being hardened, and AUP enforcement policy sets are being tightened to exclude P2P ports at ISP gateways. There are now enough P2P spread viruses that this is becoming necessary. Example is a newer virus, Kafi.b. It can use 8 languages to spread by email, and also deliberately infects and tries to spread by placing copies of itself in folders with the name share or upload in folder name. It propagates via P2P in limited fashion this way also (Kafi.b only knows two file names to use for P2P propagation, for email it uses RANDOM genned .exe names). I think I will probably stick a post up about this sometime in the general security area.

I stuck this here to show a real legit reason WHY this is being done by ISPs, as far as limiting P2P.

Straight_Man

There is also one other thing I will mention in this thread:

NICs themselves use time ticks, but not pure time ticks. If aNIC times out, you will geta drop\reestablish connect cyccle that can go almost infinite.

How does this apply here??? Time ticks used are based on two things-- CPU time cycle (which effects how app layers react and how the TCP\IP stack reacts in real time of pure seconds) AND the NIC base rate. SO, if you have a gigabit NIC synced to 100 Mbit to a router with same, and a limited bandwidth pipe from ISP, a faster box is actully likely to get deefficient on same net due to the way the funneling down makes actual flow result in a bounceback effect. Router has limited outward pipe, and can only pend so much. If its pending buffering overflows or is close to overflowing it can do a disconnect at the router of the port leading to overflow.

Optimising software works by TIGHTENING timings in TCP\IP stack handlers and making the window of data the NIC and apps use bigger, which forces more data to be pended for upload and download together. For a sinlge box, optimising software can be good, but for a multiple box connect, optimising software can actually destabilize the network locally if the demand is run through a pipe funnel as in a WAN gate due to its demand for high performance when more than one box is demanding high performance-- it can make worse the problem described in the previous paragraph and cause what you have simply by demanding more than the to-ISP WAN pipe is set up to handle in aggregate (demand of all boxes on LAN looking for web connects at once).

In this case, pulling the optimising software totally from one or more boxes might make your whole web connect not only work, but work much more stably especially if you pull it from the faster box(es) first.