Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium


2008r2 networking grief

Posted on 2011-10-18
Medium Priority
Last Modified: 2015-01-09
Hello everyone,

Recently I had an issue with a switch loop, even though it was very brief it caused problems for a few servers that started to report duplicate IP addresses without reason.
This was sorted with the "netsh int ip reset" command, well on all but one.

The server I am still struggling with does not report any thing out of the ordinary in its event log but when it communicated with some host outside its own subnet it starts dropping packets in roughly 3 seconds intervals.

So to be brief I have tried to change its IP (it works), same IP on a different server (works), change drivers from Broadcom to inbuilt MS drivers (no change).
Ping from the server to another on the same subnet (works), ping from another server to the server on the same subnet (works).
Ping from another network (packet loss), ping to an external network (packet loss).
And since this issue cam at the same time a the duplicate IP address problems on the other servers we have tried to run "netsh int ip reset" on this one too (no change) and "arpretrycount = 0" as well (no change).
There is also no difference if the server gets its IP statically or dynamically.
And changing the servers IP address (which works) is unfortunately not an option as its in production with a database used by several remote hosts.

Any fresh ideas is much appreciated.
Question by:hakonsv
  • 2
  • 2
LVL 35

Expert Comment

by:Paul MacDonald
ID: 36985834
What happens if you use a different port in the switch?

Author Comment

ID: 36985903
Sorry, I forgot to mention that I have tried to move the server to a different switch entirely and the problem persisted.
LVL 29

Expert Comment

ID: 36987882
Replace the Nic in the macine.  If it is onboard then disable it and add a Nic.  If that doesn't do anything you can just take the nic back out and go back to the original.  Just remember to set the original Nic to use DHCP before you remove or disable it,...if you don't then yo may get duplicate address notifications when you try to give the new nic the same IP the old one had.

Accepted Solution

hakonsv earned 0 total points
ID: 36990647
Actually the problem was another server. I configured a span port on the switch and did a Wireshark capture. The pattern was that the other server firs produced a broadcast ARP to ask for the domain controller IP. Right after that there was a long sequence of ARPs from the other server towards the problem server on the format:

(X=the ip of the problem server, y1..yn is random other servers on the network)

who has ip X -> Tell y1..yn. This packets had the source mac of the "other server" and destination mac of the problem server.

The pattern was always appearing just before the problem was seen for the problem server. The solution was just a restart on the other server. Now everything is running smooth. Can someone explain to me what behaviour this is? Something in Windows that get mixed up after a netwoork L2 loop?

We saw the problem only on Windows 2008R2 servers, not Windows 2003.

LVL 35

Expert Comment

by:Paul MacDonald
ID: 36992551
Very interesting - thanks for posting the resolution.

Featured Post

Concerto Cloud for Software Providers & ISVs

Can Concerto Cloud Services help you focus on evolving your application offerings, while delivering the best cloud experience to your customers? From DevOps to revenue models and customer support, the answer is yes!

Learn how Concerto can help you.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

New Windows 7 Installations take days for Windows-Updates to show up and install. This can easily be fixed. I have finally decided to write an article because this seems to get asked several times a day lately. This Article and the Links apply to…
The recent Microsoft changes on update philosophy for Windows pre-10 and their impact on existing WSUS implementations.
This tutorial will give a short introduction and overview of Backup Exec 2012 and how to navigate and perform basic functions. Click on the Backup Exec button in the upper left corner. From here, are global settings for the application such as conne…
This tutorial will show how to configure a single USB drive with a separate folder for each day of the week. This will allow each of the backups to be kept separate preventing the previous day’s backup from being overwritten. The USB drive must be s…

577 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question