Extrange Network behavior

[Alejandro]

Hi everybody, I've been working flawlessly with W7 since the very early version, but since last week I'm experimenting a very extrange network problem.

I have a Fujitsu laptop running W7 64bit and I use it for my work and at home.

In my office I have a docking station and I normally use the laptop docked with a 100Mb network connection. If I have a meeting or something I can use the corporate WiFi Network to connect.

Well, everything was running smoothly, but suddleny, my wired connection stop working.
I have network link, I have IP address served by the DHCP server, 802.1x authenticated correctly but I can only access any other IP in my local subnet, the "furthest" IP I can ping is the local router ip, and,another starnge thing is that if I ping some machine out of my network, I got a timeout, but if that machine ping's me, it works properly!!!

The first thing I thought was a routing problem. Ok, routes are correct and 0.0.0.0 points to the local adapter and then to the router.

Then, I thought that maybe the firewall was bloking the access, so I disable it completely.

Then I thought obout 802.1x, so I disble it (in my Pc and in the network port). And still the same.

If've read many post all around, and it seems like there is some inestabilty with IPV6. I've also disable it. No change, problem persists.

If I turn on the WiFi connection, then I got full access to the network. If I use my laptop at home (wired or wireless) it works. The only place it doesn't work is in my office network.

I've tried to define the network as office, home or public but it makes no diference.

To make it more extrange, I have VMWare player installed (with bridged network) and I have an XP machine on it. Well, the XP machine works perfect through the same adapter the host machine is unable to use!!!

So, at this point, in stucked. I can work, cause I use the wireless conection, but i will like to fix this problem, because due to security reasons our wireless network doesn't allow me to go everywhere.

Can anybody give me a clue???

Thx on advance
Alejandro

 

[linuxdudex12]

Sounds really strange. Have you tried ipconfig /release then ipconfig /renew in your command prompt to ensure you have a valid IP? Have others on your subnet had this problem? Have you tried connecting from different locations on the network? Since your VM works with the Network and your NIC, this leads me to believe that the Network configuration on Windows 7 is misconfigured somewhere along the line. What type of frames does the network use? My suggestion for a straight forward fix, is to try a system restore and if that does not work, back up all your data and restore your computer to its factory settings.

 

[Alejandro]

Thank's for your answer!!.

Here are the answers to your questions:

Yes. I've tried ipconfig /renew even though that if I check the connection with ipconfig /all I can see that all the parms are correct.

About the other guys in the net, no, they don't have any problem (I have to say, that there are only 2 W7 machines on the net, but the other one is working properly).

No, I haven't tried somewhere else in the net. I'll do it right away.

I don't understand the question about "what type of frames does the network use?" Do you mean if the network uses jumbo frames or somthing like that? (we don't use jumbo frames, just in case )

Regarding restoring/reinstalling is my last chance, but I'll like to understand what's going on, because when we deploy W7 in the rest of the network, this will probably happen again, and I don't like to have everybody complaining for their pc's reinstallatinions!! ( people is very extrange "don't know why" they get upset when you reinstall their computers... )

So, does someone know what's the chain of drivers/programs/configurations of the network config in W7 (or does anybody know where I can found it? )

Thx agains

 

[linuxdudex12]

Sorry about the frame thing I just mean Ethernet Frames like Ethernet_II or whatever ( don't think it matters I was just asking ). Now regarding deploying W7 to your network how do you plan on doing it? I mean are people going to have their own individual laptops or are they going to be workstations? Will they be using storage on the server instead of on their hard drives?

I think the best way to go if your going to use servers for user storage, is to have deep freeze on each computer that way when you turn they turn their computers off all of the settings go back to what they were. ( I may be wrong though ). When you said:

"Regarding restoring/reinstalling is my last chance, but I'll like to understand what's going on, because when we deploy W7 in the rest of the network, this will probably happen again, and I don't like to have everybody complaining for their pc's reinstallatinions!! ( people is very extrange "don't know why" they get upset when you reinstall their computers... )"

It suggests to me that each person will own their own individual computers and will store their data on their own hard drives. But look I'm sure the reason your W7 computer is not working with the network is because you messed up a setting, I mean I know how network managers like to toy with configurations ( are you a network manager? ) and I have messed some of my own computers to the point where a system restore is nessesary in order to establish communication with the network again ( I call it the easy fix ).

I don't think average users will toy with their network configurations, and if they do then they deserve to have their OS reinstalled.
The people on your network are not the type to mess with their settings are they?

 

[Alejandro]

Ok, I found the root of the problem. It's a new Cisco IOS version on the switch. (3750) I still don't know what my W7 machine is doing, but the situation (starting from scratch is) .

ping x.x.x.x -t -w 2000 (out of local net) fails...
ipconfig /Release (to remove IP from the interface)
In the DHCP server asign a differnte IP to my mac.
unplug-plug ether cable
Everything works well
after 6 pings (12 seconds) ping fails (no route to host)

Doing a port mirror on the switch , the ICMP response code is 0x0D (Administratively Filtered)

This only happens with the new version of the IOS in the switch and with my W7.

We have opened a case at the Cisco TAC and, as soon as I get an answer, I'll post it here.

Regards...

 

[linuxdudex12]

Sorry I can't be there to play around with it I might be able to help if I was, but your problem is too hard for me to solve in a simple forum
So you don't think reformating your computer will work? From what your saying I don't think it will either. Is it possible to just use an old version?

 

[Alejandro]

Thx anyway, only writing your problem, sometimes help you solve it. An even easy ideas (like yours about testing in some other part of the network) some time help a lot!!

As soon as I get an answer I'll post the detailed IOS versions to help others that could face this problem.

thx again

 

[hsmjsty]

Please dont take this the wrong way, but i highly doubt its the network switch. I too am having a similar problem, as are many others, and the problem seems to be more along the lines of intermitent network connectivity from a recent windows update tbd. you should know that a switch or a router would never inhibit a frame or a packet from passing through it from such a simple and expected communication (unless explicitly, either intentional or not told to do so). i am not saying its impossible, but in my experience the root cause must be with the lowest common denomonator and that is the pc since others systems are behaving fine, both in yours and my situation.

one difference is that ipv6, once disabled, seemed to allow my one of very many systems to behave as required, no longer dropping its connections.

keep in mind that i dont claim to know everything about your problem, but theres a good chance valuable time may be lost if you dont pursue the windows side as well.

-long time network engineer

 

[Alejandro]

At the very beginig of this problem I was quite skeptical as you, I never thougth that could be something wrong with the switch (I'm also a net. eng) but when we span the network port and traffic stops coming to the Pc, then I realize that there was something wrong with the net.

Well, the root cause of this problem is quite complex (it tooks us almost 2 weeks with Cisco TAC to find it). The problem appears if your machine starts putting IP frames with a wider network mask than the mask configured in the switch. Why this happen? In the first machine we found the problem we don't know why this machine starts putting that kind of frames (seems to be related with VMWARE, but we are not sure), but you can reproduce it easyly confguring your network with a mask much wider in the ethernet inteface.

The bug in the Cisco switch is that, when this happens, it will forward the mac address of the pc over the trunk to the upstream switch. This upstrem switch will lern that MAC address for the Pc IP is the real MAC of the Pc (instead of having the downstream swicth MAC address). When traffic cames through the downstream switch, as far as that switch doesn't have that mac, traffic is dropped. That's why local traffic worked fine, but routed traffic, doesn't.

There is a patch for the Cisco IOS to correct this behavior. It will block frames with wrong network mask to propagate through the network

By the way, the version of IOS that have the mistake is the one that Cisco rewrote to implement 802.1x open mode.

Hope this helps someone