Windows NT and UDP checksums (fwd)

> Peter Lothberg writes :
> From roll at Stupi.SE Sun Apr 28 15:37:15 1996
> Date: Sun, 28 Apr 96 15:35:17 MET DST
> From: Peter Lothberg <roll at Stupi.SE>
> Subject: Windows NT and UDP checksums
> To: staff at ripe.net
> Message-Id: <CMM.0.90.0.830698534.roll at Junk.Stupi.SE>
> 
> 
> It was discussed at the ripe meeting, if NT could support UDP checksums or not,
> it turns out that it can...
> 
> --Peter
> 
> ------------------------------------------------------------------------
> REG: TCP/IP Transport Entries, PART 1
> Article ID: Q102973
> Revision Date: 05-APR-1996
> 
> The information in this article applies to:
> 
>  - Windows NT operating system version 3.1
>  - Windows NT Advanced Server version 3.1
> 
> 
> The article contains REGISTRY entries for the TCP/IP Transport Entries, Part 
> 1. These subgroups are included:
> 
>  - TCP/IP Parameters Subkey Entries
>  - Adapter Card Parameters for TCP/IP
> 
> 
> This is the first of two articles on these entries; for the other entries, 
> see "TCP/IP Transport Entries, Part 2."
> 
> TCP/IP TRANSPORT ENTRIES
> 
> The various TCP/IP keys do not appear in the Registry unless TCP/IP is 
> installed using the Network icon in Control Panel.
> 
> With Registry Editor, you can modify the following parameters for the TCP/IP 
> transport. This section does not include all the TCP/IP
> parameters that can be set using the Networks application in Control Panel.
> 
> The startup parameters defined in this section are found in these subkeys of
> HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services:
> 
>    TCPIP\Parameters
>    adapter_name#\Parameters\TCPIP, (where adapter_name# indicates a
>                       Services subkey for a network adapter
>                       card)
>    Ftpsvc\Parameters
>    NBT\Parameters
>    Streams\Parameters
> 
> 
> Parameters for network bindings for this service are described in the 
> article "NetRules Subkey Entries." See also
> IsDomainMasterBrowser in the article "Browser Service Entries."
> 
> TCP/IP PARAMETERS SUBKEY ENTRIES
> 
> The entries for TCP/IP parameters appear under the following Registry path:
> 
>    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
> 
> 
> ArpCacheLife REG_DWORD Number of Seconds
> 
> Default: 600  (10 minutes)
> 
> 
> Determines the default lifetime for entries in the ARP cache table. Once an 
> entry is placed in the ARP cache, it is allowed to remain
> there until its lifetime expires or until its table entry is reused because 
> it is the oldest entry.
> 
> ArpCacheSize REG_DWORD Number Default: 62
> 
> Determines the maximum number of entries that the ARP cache table can hold. 
> The ARP cache is allowed to grow dynamically until
> this size is reached. After the table reaches this size, new entries can 
> only be added by replacing the oldest entries that exist.
> 
> DatabasePath REG_EXPAND_SZ Pathname Default: 
> %SystemRoot%\system32\drivers\etc
> 
> Determines where TCP/IP and NBT look for the hosts, services, networks, 
> protocols, NETRC, and LMHOSTS files.
> 
> IpEnableRouter REG_DWORD 0 or 1 Default: 0 (false)
> 
> Determines whether IP routing is enabled between local interfaces. IP 
> routing is always enabled for packets generated by the local
> host. This parameter determines whether, for packets received on an 
> interface and not destined for this host, IP will attempt to actively
> forward the packets to hosts that can be reached via its other interfaces.
> 
> IpReassemblyTimeout REG_DWORD Number of seconds Default: 60 seconds
> 
> Determines how long IP accepts fragments when attempting to reassemble a 
> previously fragmented packet. That is, if a packet is
> fragmented, all of the fragments must make it to the destination within this 
> time limit; otherwise, the fragments will be discarded and
> the packet will be lost.
> 
> TcpDisableReceiveChecksum REG_DWORD 0 or 1 Default: 0 (false, that is, 
> checksums will be checked on receives)
> 
> Specifies whether Checksums is disabled on receive.
> 
> 
> TcpDisableSendChecksum REG_DWORD 0 or 1
> 
> Default: 0 (false, that is, checksums will be generated on sends)
> 
> Specifies whether Checksums is disabled on send.
> 
> 
> TcpKeepCnt REG_DWORD Number in Minutes
> 
> Default: 120
> 
> 
> Specifies how often TCP/IP will generate keep-alive traffic. When TCP/IP 
> determines that no activity has occurred on the connection
> within the specified time, it generates keep-alive traffic to probe the 
> connection. After trying TcpKeepTries number of times to deliver
> the keep-alive traffic without success, it marks the connection as down.
> 
> TcpKeepTries REG_DWORD Number Default: 20
> 
> Specifies the maximum number of times that TCP/IP will attempt to deliver 
> keep-alive traffic before marking a connection as down.
> 
> TcpLogLevel REG_DWORD Number Default: 16 (log everything)
> 
> Specifies how verbose TCP/IP should be about logging events in the event 
> log. The highest level of verbosity is 16, and 1 is the
> lowest level. The following shows general information about these levels.
> 
>    Level   Events to be included
>    ---------------------------------------------
>    1     Only the most critical errors
>    4     Serious protocol violations
>    8     Nonserious protocol violations
>    12    Information about unusual events
>    16    Information about unusual events that
>        some networks normally allow
> 
> 
> TcpMaxConnectAttempts REG_DWORD Number
> 
> Default: 3
> 
> 
> Specifies the maximum number of times TCP/IP attempts to establish a 
> connection before reporting failure. The initial delay between
> connection attempts is 3 seconds. This delay is doubled after each attempt.
> 
> TcpMaxRetransmissionAttempts REG_DWORD Number Default: 7
> 
> Specifies the maximum number of times that TCP/IP attempts to retransmit a 
> piece of data on an established connection before ending
> the connection. The initial delay before retransmitting is based on the 
> current estimate TCP/IP makes of the round-trip time on the
> connection. This delay is doubled after each retransmission. Acknowledgment 
> of the data results in a recalculation of the estimate for
> the round-trip time.
> 
> TcpNumConnections REG_DWORD Number Default: 64
> 
> Specifies the maximum number of TCP endpoints.
> 
> 
> TcpRecvSegmentSize REG_DWORD Bytes
> 
> Default: 1460
> 
> 
> Specifies the maximum receive segment size.
> 
> 
> TcpSendDownMax REG_DWORD Number
> 
> Default: 16384
> 
> 
> Specifies the maximum number of bytes queued by TCP/IP.
> 
> 
> TcpSendSegmentSize REG_DWORD Bytes
> 
> Default: 1460
> 
> 
> Specifies the maximum send segment size.
> 
> 
> TcpWindowSize REG_DWORD Number
> 
> Default: 8192
> 
> 
> Sets the size of the TCP send and receive windows, which is the amount of 
> data that can be accepted in a single transaction. This
> parameter is important in transferring files between a client and a server 
> and is critical for performance for one-way traffic, such as for
> FTP.
> 
> UdpDisableReceiveChecksum REG_DWORD 0 or 1 Default: 0 (false--that is, 
> checksums will be checked on receives)
> 
> Specifies whether Checksums is disabled on receive.
> 
> 
> UdpDisableSendChecksum REG_DWORD 0 or 1
> 
> Default: 0 (false--that is, checksums will be generated on sends)
> 
> Specifies whether Checksums is disabled on send.
> 
> 
> UdpNumConnections REG_DWORD Number
> 
> Default: 64
> 
> 
> Specifies the maximum number of UDP endpoints.
> 
> 
> ADAPTER CARD PARAMETERS FOR TCP/IP
> 
> These parameters for TCP/IP are specific to individual network adapter 
> cards. These appear under the following Registry path, where
> adapter name# refers to the Services subkey for the specific adapter card:
> 
>    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
>       \adapter name#\Parameters\Tcpip
> 
> 
> BroadcastType REG_DWORD 0 or 1
> 
> Default: 1 (all 1 s)
> 
> 
> Determines whether broadcast packets contain all 0 s or all 1 s as the 
> broadcast address. The most common broadcast type is all 1 s.
> The all-0 s setting is provided for compatibility with BSD 4.2 systems.
> 
> ForwardBroadcasts REG_DWORD 0 or 1 Default: 0 (false)
> 
> Specifies whether broadcasts should be forwarded between adapters. If 
> enabled, broadcasts seen by this interface are forwarded to
> other IP interfaces.
> 
> KeepAlive REG_DWORD 0 or 1 Default: 1 (true)
> 
> Determines whether TCP connections that request keep-alive packets result in 
> keep-alive packets being sent. This feature is used to
> determine when inactive connections can be disconnected. When a connection 
> becomes inactive, keep-alive packets are periodically
> exchanged. When 20 (the default value for TCPKeepTries) consecutive 
> keep-alive packets go unanswered, the connection is broken.
> This disconnect is initiated by the endpoint that is sending keep-alive 
> packets.
> 
> MTU REG_DWORD Number in octets Default: 0 (That is, use the value supplied 
> by the adapter.)
> 
> Specifies the maximum transmission unit size of an interface. Each interface 
> used by TCP/IP may have a different MTU value specified.
> The MTU is usually determined through negotiation with the lower driver, 
> using that lower driver s value. However, that value may be
> overridden.
> 
> Ideally, the MTU should be large enough to hold any datagram in one frame. 
> The limiting factor is usually the technology making the
> transfer. Some technologies limit the maximum size to as little as 128; 
> Ethernet limits transfers to 1500; and proNet-10 allows as many as
> 2044 octets per frame.
> 
> Datagrams larger than the MTU value are automatically divided into smaller 
> pieces called fragments; size is a multiple of eight octets.
> Fragmentation usually occurs somewhere through which the traffic must pass 
> whose MTU is smaller than the encapsulated datagram.
> If fragmentation occurs, the fragments travel separately to the destination 
> computer, where they are automatically reassembled before
> the datagram is processed.
> 
> RouterMTU REG_DWORD Number in octets Default: 0 (That is, use the value 
> supplied by the lower interface.)
> 
> Specifies the maximum transmission unit size that should be used when the 
> destination IP address is on a different subnet. Each
> interface used by TCP/IP may have a different RouterMTU value specified. In 
> many implementations, the value of RouterMTU is set
> to 576 octets. This is the minimum size that must be supported by any IP 
> node. Because modern routers can usually handle MTUs
> larger than 576 octets, the default value for this parameter is the same 
> value as that used by MTU.
> 
> Trailers REG_DWORD 0 or 1 Default: 0 (false)
> 
> Specifies whether the trailer format is used. This feature provides 
> compatibility with BSD 4.2 systems. When this feature is enabled,
> TCP/IP header information follows the data area of IP packets.
> 
> Reference: "The Windows NT Resource Kit for Operating System Version 3.1"
> 
> Additional reference words: prodnt 3.10
> 
> 
> 
> KBCategory: kbother
> KBSubcategory: ntregistry
> 
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> 
> Copyright Microsoft Corporation 1996.
> 
> 
> 
> 
>