TCP/IP settings for Windows NT and 2000

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TCP/IP is a widely used Wan protocol. In NT and 2000 systems, some of its parameters are provided by the network or DHCP server in the control panel. Next we will look at the TCP/IP Settings from the Registry's perspective. Most of the settings in the Registry are optimal, but in some cases, these settings may not meet the special needs of some users, so it is necessary to modify the registry. However, it is dangerous to modify the Registry. Generally, do not modify it arbitrarily.
　　
All TCP/IP settings are under the two registry keys:
　　
HKEY_LOCAL_MACHINE/system/CurrentControlSet/service/TCPIP/parameters
HKEY_LOCAL_MACHINE/system/CurrentControlSet/service/<adapter Name>/TCPIP/parameters
The following values are the default configurations installed with the control panel Network Configuration:
　　
Databasepath: Database path
Key: TCPIP/parameters
Value Type: reg_expand_sz
Valid value: a valid path
Default Value: % SystemRoot %/system32/Drivers/etc
Description: This parameter specifies the location where standard Internet data files (hosts, LmHosts, networks, protocols) are stored. These files are used by the Windows Sockets interface.
　　
Forwardbroadcasts: forward broadcast
Key: TCPIP/parameters
Value Type: REG_DWORD
Valid value: 0 or 1 indicates false or true.
Default Value: 0 (false)
Description: This option is ignored because broadcast Forwarding is not supported.
　　
Usezerobroadcast: use zero Broadcast
Key:/parameters/TCPIP
　　
Note: in Windows 2000, the value of this item is TCPIP/parameters/interfaces/ID for adapter.
　　
Value Type: REG_DWORD
Valid value: 0 or 1 indicates false or true.
Default Value: 0 (false)
Description: if the value of this item is 1, the broadcast address is all zero (0.0.0.0), and the normal broadcast address is all one (broadcast bandwidth 255.255.255), because some are evolved from the BSD implementation, therefore, they use zero as the broadcast address.
　　
The following parameters may not exist in the corresponding table items of the Registry. You can manually add them.
　　
　　
Arpalwayssourceroute: ARP source route
Key: TCPIP/parameters
Value Type: REG_DWORD
Valid value: 0 or 1 indicates false or true.
Default Value: 0 (false)
Description: setting this parameter to true indicates that TCP/IP transmits ARP queries on the Token Ring Based on the source route. Generally, the first request for ARP resolution does not contain the source route. When the first request fails and the second request is parsed, the source route is added.
　　
Arpuseethersnap: transmitted using SNAP Encoding
Key: TCPIP/parameters
Value Type: REG_DWORD
Valid value: 0 or 1 indicates false or true.
Default Value: 0 (false)
Description: If this parameter is set to true, TCP uses 802.3 snap encoding to transmit data packets. Data packets are transmitted in Dix format by default. But it can receive two types of data packets.
　　
Defaulttos: default service type
Key: TCPIP/parameters
Value Type: REG_DWORD
Valid range: 0-255
Default Value: 0
Description: Specifies the service type domain in the IP header. For more information about the specific domain, see IP protocol. However, this option is invalid in Windows2000.
　　
Defaultttl: Default TTL
Key: TCPIP/parameters
Value Type: REG_DWORD
Seconds/hops
Valid value: 1-255
Default Value: 32 for nt3.51 and 128 for NT4
Description: lifecycle of a package. This period refers to the number of routers that can pass through the network. When the number of routers exceeds this period, the package is discarded.
　　
EnableDeadGWDetect: performs the Dead Gateway Detection.
Key: TCPIP/parameters
Value Type: REG_DWORD
Valid value: 0 or 1 indicates false or true.
Default Value: 1 (true)
Description: setting this value to 1 indicates that TCP can detect the Dead Gateway. When an IP address sends several packets to a gateway, TCP requires the IP address to transmit packets to the slave gateway. The slave gateway is set in the advanced section of TCP/IP configuration.
　　
Enablepmtubhdetect: allows detection of black hole Routers
Key: TCPIP/parameters
Value Type: REG_DWORD
Valid value: 0 or 1 indicates false or true.
Default Value: 0 (false)
Description: If this parameter is set to true, TCP can detect the black hole router. A black hole router is a router that does not return an ICMP error message when packet segmentation is not allowed. TCP depends on the returned ICMP messages to test the maximum packet length path.
　　
Enablepmtudiscovery: Maximum package length path detection is allowed.
Key: TCPIP/parameters
Value Type: REG_DWORD-Boolean
Valid value: 0 or 1 indicates false or true.
Default Value: 1 (true)
Description: if this value is true, TCP can detect the maximum packet length path. The size of the data packet that can be transmitted in the detected path is larger than that in other paths. This path can reduce IP packet segmentation and improve transmission efficiency. If this value is set to false, TCP will transmit 576 bytes of data packets to all non-local hosts.
　　
Forwardbuffermemory: Forwarding buffer size
Key: TCPIP/parameters
Value Type: REG_DWORD-number of bytes
Valid value: Between MTU and a value smaller than 0xffffffff
Default Value: 74240
Description: This option determines how much memory the vro uses to buffer the route package. When the buffer zone is full, the router randomly discards packets from the buffer zone. The buffer data size is 256, so the actual memory size is set to a * 256. For large packets, multiple buffers are chained for storage, and all headers are stored separately. If no route forwarding is performed, this option is ignored.
　　
Igmplevel: determines the degree of participation in multicast and IGMP protocols
Key: TCPIP/parameters
Value Type: REG_DWORD
Valid range: 0, 1, 2
Default Value: 2
Description: This parameter determines the degree to which the system participates in IP multicast and IGMP protocols. Level 0: The system does not support multicast. Level 1: The system can issue multicast packets. Level 2, the system can issue multicast packets and participate in IGMP and receive multicast packets.
　　
Keepaliveinterval: determines the interval between separated keep alive retransmission.
Key: TCPIP/parameters
Value Type: REG_DWORD
Valid value: 1-0 xffffffff
Default Value: 1000 (1 second)
Description: determines the interval between separated keep alive retransmission. Once a response is received, the next keep alive retransmission time is controlled by KeepAliveTime again. If no response is received after TCPMaxDataRetransmissions, the connection is dropped.
　　
KeepAliveTime: determines the TCP interval to determine whether the current connection is still in the connection state.
Key: TCPIP/parameters
Value Type: REG_DWORD
Valid value: 1-0 xffffffff
Default Value: 7,200,000 (2 hours)
Description: determines the TCP interval to determine whether the current connection is still in the connection state. If the remote system still has a response, it indicates that the connection is in the connection status. The release of keep alive data is not the default one. It must be controlled by specific applications.
　　
MTU: Maximum Transmission Unit
Key:/parameters/TCPIP
　　
Note: in Windows 2000, this option is available under key: TCPIP/parameters/interfaces /.
　　
Value Type: REG_DWORD number
Valid range: 68
Default Value: 0 xffffffff
Description: Maximum package length that can be transmitted in the lower layer. This length includes a packet header, which can be included in multiple data packets.
　　
Numforwardpackets: number of IP headers saved by the router packet queue
Key: TCPIP/parameters
Value Type: REG_DWORD
Valid range: 1 to a value smaller than 0xffffffff
Default Value: 50
Description: The number of IP headers saved by the router packet queue. If this value is exceeded, the router randomly chooses to discard it in the queue. This value must be greater than the forwardbuffermemory/maximum IP data size, but not greater than forwardbuffermemory/256. If no route is enabled, this option is ignored.
　　
Tcpmaxconnectretransmissions: Maximum number of re-transmission requests (SYN)
Key: TCPIP/parameters
Value Type: REG_DWORD
Valid range: 0-0 xffffffff
Default Value: 3
Description: The maximum number of retransmissions (SYN. The Retransmission timeout value is multiplied by 2 after a successful retransmission is received, and the initial timeout value is 3 seconds.
　　
TCPMaxDataRetransmissions: number of TCP retransmission times for a single data segment
Key: TCPIP/parameters
Value Type: REG_DWORD
Valid value: 0-0 xffffffff
Default Value: 5
Description: This parameter controls the number of times a single data segment is retransmitted over TCP.
　　
Tcpnumconnections: Number of connections simultaneously opened
Key: TCPIP/parameters
Value Type: REG_DWORD-Number
Valid value: 0-0 xfffffe
Default Value: 0 xfffffe
Description: limits the number of connections opened at the same time by TCP.
　　
Tcptimedwaitdelay: the longest time to stop in the time_wait status
Key: TCPIP/parameters
Value Type: REG_DWORD
Valid value: 30-300
Default Value: 0xf0 (240 seconds)
Description: maximum time to stop in the time_wait status. When it is in time_wait, the socket cannot be reused. This status is also called "2msl.
　　
Tcpuserfc1122urgentpointer: explains the status of the emergency pointer.
Key: TCPIP/parameters
Value Type: REG_DWORD
Valid value: 0 or 1 indicates false or true.
Default Value: 0 (false)
Description: This parameter determines whether to use the RFC 1122 standard or the BSD system standard for TCP transmission of emergency data. These two standards are incompatible. Generally, Windows NT uses the BSD mode.
　　
Tcpwindowsize: determines the maximum length of the receiving window.
Key: TCPIP/parameters
Value Type: REG_DWORD
Valid range: 0-0 xFFFF
Default Value: less than 0xffff. For Ethernet, 8760
Description: determines the size of the TCP receiving window. The number of unconfirmed packets that can be buffered by TCP specified in the receiving window. Generally, a larger receiving window can improve the system efficiency.