.Definition of Terms Used

DOCSIS( Data Over Cable Service Interface Specification ) is the Cable Modem standard that defines the interface requirements of high-speed data transmission over cable networks. You can also see the CableLabs® Certified^TM logo on some modems, which also means the modem is DOCSIS compliant.For more info on this and other upcoming project, visit CableLabs  

DSL ( Digital Subscriber Line ) is another method of high-speed data transfer over ordinary copper telephone lines. xDSL refers to different variations of DSL, such as ADSL, HDSL, SDSL and RADSL.

ADSL( Asymmetric DSL) is the "asymetric" form of DSL. It's called that since most of its two-way bandwidth is devoted to the downstream direction, sending data to the user.

HDSL (High bit-rate DSL) symmetrical DSL type, an equal amount of bandwidth is available in both upstream and downstream directions. Runs over two twisted pairs.

SDSL (Single line DSL) similar to HDSL, however it runs on a single twisted pair.

RADSL (Rate-Adaptive DSL) is an ADSL technology from in which software is able to determine the rate at which signals can be transmitted on a given customer phone line and adjust the delivery rate accordingly.

PPPoE ( Point-to-Point Protocol over Ethernet ) is a method for building PPP sessions and encapsulating packets, as described in RFC2516. Although it is not a standard, PPPoE is already being used by a number of DSL providers. It requires either routers that have built-in PPPoE support, or PPPoE software to "dial up" and establish the session.

Note: If your ISP has implemented PPPoE and you are tweaking the Windows Registry, note that PPPoE supports MaxMTU=1492 or less, rather than 1500.

 Definition of Registry Terms

MTU ( Maximum Transmission Unit ) is the greatest amount of data that can be transferred in one physical frame on the network. If a packet that has a smaller MTU than the packet's frame length is sent, fragmentation will occur. For Ethernet, 1500 is the maximum, and recommended MTU. The unofficial MTU for SLIP servers is 1006.

MSS ( Maximum Segment Size ) defines the largest segment of TCP data that the Winsock is prepared to receive. When a connection is established, the two ends agree to use the smaller of each end's value. Because headers are typically 40 bytes (20byte IP and 20byte TCP headers), set the MSS to 40 less than the MTU. Note that Windows calculates MSS automatically, based on MaxMTU. 

DefaultRcvWindow (TCP Receive Window, or simply RWIN).
Note: the correct setting under Windows NT 4 is TcpWindowSize.
Determines how much data the receiving computer is prepared to get. A too large RWIN will result in greater loss of data if a packet is lost or damaged. A too small RWIN will be very slow, as each packet will have to be acknowledged before the next packet is sent. For best results, the RWIN should be set to a multiple of the TCP MSS.

Tcp1323Opts  Large window support ( supported only in Windows 98 ). Used when an application requests a Winsock socket to use buffer sizes greater than 64K. In previous implementations the TCP window size was limited to 64K, this limit is raised to 2**30 through the use of TCP large window support as defined in RFC1323 and implemented in Winsock 2.

SackOpts Selective Acknowledgements ( see RFC 2018 ).
Selective acknowledgements allow TCP to recover from IP packet loss without resending packets that were already received by the receiver. Most useful when employed with TCP large windows.

MaxDupAcks Fast Retransmission and Fast Recovery of TCP connections that are encountering IP packet loss in the network. Allow a TCP sender to quickly infer a single packet loss by reception of duplicate acknowledgements for a previously sent and acknowledged TCP/IP packet. This mechanism is useful when the network is intermittently congested. The reception of 3 successive duplicate acknowledgements indicates to the TCP sender that it can resend the last unacknowledged TCP/IP packet (fast retransmit) and not go into TCP slow start due to a single packet loss (fast recovery).

DefaultTTL Specifies the default Time To Live value set in the header of outgoing IP packets. The TTL determines the maximum amount of time an IP packet can live in the network without reaching its destination. It is effectively a limit on the number of routers an IP packet may pass through before being discarded.

PMTUDiscovery ( as defined in RFC1191 ).
Note: the setting under Windows NT 4 is EnablePMTUDiscovery.
Determines whether TCP uses a fixed, default maximum transmission unit (MTU) or attempts to find the actual MTU. If the value of this entry is 0, TCP uses an MTU of 576 bytes for all connections to computers outside of the local subnet. If the value of this entry is 1, TCP attempts to discover the MTU (largest packet size) over the path to a remote host.

PMTUBlackHoleDetect 
Note: the setting under Windows NT 4 is EnablePMTUBHDetect.
When enabled, causes TCP to try to detect "Black Hole" routers while doing Path MTU Discovery. A "Black Hole" router does not return ICMP Destination Unreachable messages when it needs to fragment an IP datagram with the Don't Fragment bit set. TCP depends on receiving these messages to perform Path MTU Discovery. With this feature enabled, TCP will try to send segments without the Don't Fragment bit set if several retransmissions of a segment go unacknowledged. If the segment is acknowledged as a result, the MSS will be decreased and the Don't Fragment bit will be set in future packets on the connection. Enabling black hole detection increases the maximum number of retransmissions performed for a given segment.

Thanks To SpeedGuide.Net 
For This List Of Terms

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