Watch dropped IP packets
Serdar Yegulalp

Losing too many TCP/IP packets? Could be because you've passed a default limit set in the registry for reassembly headers. If the limit's exceeded, the software may drop out-of-order packets without warning. But you can stop that with a simple registry hack.

Got a Windows 2000 administrator tip of your own? Why not

Requires Free Membership to View

send it in? We'll post it on our Web site, and enter you in our tips contest for some great prizes.

Because of the way TCP/IP works, sometimes packets are deliberately sent out of order (or "fragmented"). They are, of course, reassembled at their destination and defragmented. When the Microsoft TCP/IP stack does this, it looks for a reassembly header to place the fragmented packets into the correct order. If it can't find the header, it may create one.

Since the stack has a limit of 100 such headers, excessive packet fragmentation may result in new fragmented packets simply being dropped without warning. This limit is soft-coded, so if you're finding a lot of packets going missing on you, you may want to raise it.

To change it, fire up your favorite registry editor (or just plain old REGEDIT) and go to HKEY_LOCAL_MACHINESystemCurrentControlSetServicesTcpipParameters. Add the value MaximumReassemblyHeaders (REG_DWORD) data type, and set the data value to a Decimal number between 100 and 65535 (to specify the number of headers). Then reboot.

Serdar Yegulalp is the editor of the Windows 2000 Power Users Newsletter.

Did you like this tip? We'd like to know. Email to share your opinion.

This was first published in September 2001

There are Comments. Add yours.

TIP: Want to include a code block in your comment? Use <pre> or <code> tags around the desired text. Ex: <code>insert code</code>

REGISTER or login:

Forgot Password?
By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy
Sort by: OldestNewest

Forgot Password?

No problem! Submit your e-mail address below. We'll send you an email containing your password.

Your password has been sent to:

Disclaimer: Our Tips Exchange is a forum for you to share technical advice and expertise with your peers and to learn from other enterprise IT professionals. TechTarget provides the infrastructure to facilitate this sharing of information. However, we cannot guarantee the accuracy or validity of the material submitted. You agree that your use of the Ask The Expert services and your reliance on any questions, answers, information or other materials received through this Web site is at your own risk.