Previous | Table of Contents | Next |
I-309 Problem: when you try to connect to Web servers or FTP sites, you often time out or must retry many times before you finally connect. The problem may be that your time to live (TTL) is too small. TTL is a TCP/IP parameter that controls how many hops or routers your packet can go through before it is discarded by the network. Every time the packet goes through a router, its value is decremented by 1. When the value reaches zero, the packet is discarded. With the proliferation of servers and routers on the network, a value that was once a reasonable TTL is now not practical. To modify the TTL, change this entry.
Hive: | HKEY_LOCAL_MACHINE |
Key: | System\CurrentControlSet\Services\Tcpip\Parameters |
Add the following value under the Parameters key:
Value Name: | DefaultTTL |
Data Type: | REG_DWORD |
Value: | 255 |
Restart your machine for these new values to take effect.
I-310 Sometimes it isnt possible to check all the static routes of a remote machine. You can, however, see which persistent routes a particular system has set up. Use the following registry key and its associated values to see these routes.
Hive: | HKEY_LOCAL_MACHINE |
Key: | System\CurrentControlSet\Services\Tcpip\Parameters\ PersistentRoutes |
Add the following value
Value Name: | 204.56.55.100,255.255.255.255,127.0.0.1,1 |
Data Type: | REG_SZ |
Value: |
The value name is the actual route. The format is destination address,subnet mask,source address,metric. You must then make it a REG_SZ entry with a blank value. If you add or delete entries here, you must exit Regedt32.exe for them to take effect on the remote machine.
I-311 TCP/IP on Windows NT uses a lot of different files for its information. These files are located in the following registry key.
Hive: | HKEY_LOCAL_MACHINE |
Key: | System\CurrentControlSet\Services\Tcpip\Parameters |
Value Name: | DatabasePath |
Data Type: | REG_EXPAND_SZ |
Value: | %SystemRoot%\system32\drivers\etc |
The actual files stored there are Hosts, Lmhosts, Networks, Protocols, and Services. By altering the directory where these files point, it is possible to have a central location or to have several different working sets of these files.
I-312 If you have trouble with PPTP connections timing out on particularly slow connections, try increasing the following registry parameter:
Hive: | HKEY_LOCAL_MACHINE |
Key: | System\CurrentControlSet\Services\Tcpip\Parameters |
Value Name: | PPTPTcpMaxDataRetransmissions |
Data Type: | REG_DWORD |
Value: | 9 |
Increasing the default value gives PPTP packets a better chance of getting through on heavily congested networks or particularly slow links. Restart your machine for this value to take effect.
I-313 If you have a mixed network and need your broadcast packets to be the 0-style broadcasts packets (that is, 0.0.0.0 instead of the default 1-style, or 255.255.255.255), change this registry value:
Hive: | HKEY_LOCAL_MACHINE |
Key: | System\CurrentControlSet\Services\Tcpip\Parameters |
Value Name: | UseZeroBroadcast |
Data Type: | REG_DWORD |
Value: | 1 |
I-314 If you have intermittent problems with your gateways (and who doesnt?), you probably have already established a set of alternate gateways. Use this registry entry to have Windows NT automatically switch to the backup gateway if the current gateway is not responding.
Hive: | HKEY_LOCAL_MACHINE |
Key: | System\CurrentControlSet\Services\Tcpip\Parameters |
Value Name: | EnableDeadGWDetect |
Data Type: | REG_DWORD |
Value: | 1 |
The default value is 1, which enables the feature. Setting this value to 0 disables the detection. Restart your machine for this value to take effect.
I-315 By default, Windows NT tries to discover the maximum transmission unit (MTU) over a given path to a remote host. By finding the largest packet size it can send, Windows NT maintains a good throughput. Setting this value to 0 causes the MTU to be set to 576 bytes for all connections other than hosts or local subnet destinations.
Hive: | HKEY_LOCAL_MACHINE |
Key: | System\CurrentControlSet\Services\Tcpip\Parameters |
Value Name: | EnablePMTUDiscovery |
Data Type: | REG_DWORD |
Value: | 1 |
Restart your machine for these values to take effect.
Previous | Table of Contents | Next |