4.2.5 TCP REQUIREMENT SUMMARY

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FEATURE                                          |SECTION | | | |T|T|e
-------------------------------------------------|--------|-|-|-|-|-|--
                                                 |        | | | | | |
Push flag                                        |        | | | | | |
  Aggregate or queue un-pushed data              |4.2.2.2 | | |x| | |
  Sender collapse successive PSH flags           |4.2.2.2 | |x| | | |
  SEND call can specify PUSH                     |4.2.2.2 | | |x| | |
    If cannot: sender buffer indefinitely        |4.2.2.2 | | | | |x|
    If cannot: PSH last segment                  |4.2.2.2 |x| | | | |
  Notify receiving ALP of PSH                    |4.2.2.2 | | |x| | |1
  Send max size segment when possible            |4.2.2.2 | |x| | | |
                                                 |        | | | | | |
Window                                           |        | | | | | |
  Treat as unsigned number                       |4.2.2.3 |x| | | | |
  Handle as 32-bit number                        |4.2.2.3 | |x| | | |
  Shrink window from right                       |4.2.2.16| | | |x| |
  Robust against shrinking window                |4.2.2.16|x| | | | |
  Receiver's window closed indefinitely          |4.2.2.17| | |x| | |
  Sender probe zero window                       |4.2.2.17|x| | | | |
    First probe after RTO                        |4.2.2.17| |x| | | |
    Exponential backoff                          |4.2.2.17| |x| | | |
  Allow window stay zero indefinitely            |4.2.2.17|x| | | | |
  Sender timeout OK conn with zero wind          |4.2.2.17| | | | |x|
                                                 |        | | | | | |
Urgent Data                                      |        | | | | | |
  Pointer points to last octet                   |4.2.2.4 |x| | | | |
  Arbitrary length urgent data sequence          |4.2.2.4 |x| | | | |
  Inform ALP asynchronously of urgent data       |4.2.2.4 |x| | | | |1
  ALP can learn if/how much urgent data Q'd      |4.2.2.4 |x| | | | |1
                                                 |        | | | | | |
TCP Options                                      |        | | | | | |
  Receive TCP option in any segment              |4.2.2.5 |x| | | | |
  Ignore unsupported options                     |4.2.2.5 |x| | | | |
  Cope with illegal option length                |4.2.2.5 |x| | | | |
  Implement sending & receiving MSS option       |4.2.2.6 |x| | | | |
  Send MSS option unless 536                     |4.2.2.6 | |x| | | |
  Send MSS option always                         |4.2.2.6 | | |x| | |
  Send-MSS default is 536                        |4.2.2.6 |x| | | | |
  Calculate effective send seg size              |4.2.2.6 |x| | | | |
                                                 |        | | | | | |
TCP Checksums                                    |        | | | | | |
  Sender compute checksum                        |4.2.2.7 |x| | | | |
  Receiver check checksum                        |4.2.2.7 |x| | | | |
                                                 |        | | | | | |
Use clock-driven ISN selection                   |4.2.2.9 |x| | | | |
                                                 |        | | | | | |
Opening Connections                              |        | | | | | |
  Support simultaneous open attempts             |4.2.2.10|x| | | | |
  SYN-RCVD remembers last state                  |4.2.2.11|x| | | | |
  Passive Open call interfere with others        |4.2.2.18| | | | |x|
  Function: simultan. LISTENs for same port      |4.2.2.18|x| | | | |
  Ask IP for src address for SYN if necc.        |4.2.3.7 |x| | | | |
    Otherwise, use local addr of conn.           |4.2.3.7 |x| | | | |
  OPEN to broadcast/multicast IP Address         |4.2.3.14| | | | |x|
  Silently discard seg to bcast/mcast addr       |4.2.3.14|x| | | | |
                                                 |        | | | | | |
Closing Connections                              |        | | | | | |
  RST can contain data                           |4.2.2.12| |x| | | |
  Inform application of aborted conn             |4.2.2.13|x| | | | |
  Half-duplex close connections                  |4.2.2.13| | |x| | |
    Send RST to indicate data lost               |4.2.2.13| |x| | | |
  In TIME-WAIT state for 2xMSL seconds           |4.2.2.13|x| | | | |
    Accept SYN from TIME-WAIT state              |4.2.2.13| | |x| | |
                                                 |        | | | | | |
Retransmissions                                  |        | | | | | |
  Jacobson Slow Start algorithm                  |4.2.2.15|x| | | | |
  Jacobson Congestion-Avoidance algorithm        |4.2.2.15|x| | | | |
  Retransmit with same IP ident                  |4.2.2.15| | |x| | |
  Karn's algorithm                               |4.2.3.1 |x| | | | |
  Jacobson's RTO estimation alg.                 |4.2.3.1 |x| | | | |
  Exponential backoff                            |4.2.3.1 |x| | | | |
  SYN RTO calc same as data                      |4.2.3.1 | |x| | | |
  Recommended initial values and bounds          |4.2.3.1 | |x| | | |
                                                 |        | | | | | |
Generating ACK's:                                |        | | | | | |
  Queue out-of-order segments                    |4.2.2.20| |x| | | |
  Process all Q'd before send ACK                |4.2.2.20|x| | | | |
  Send ACK for out-of-order segment              |4.2.2.21| | |x| | |
  Delayed ACK's                                  |4.2.3.2 | |x| | | |
    Delay < 0.5 seconds                          |4.2.3.2 |x| | | | |
    Every 2nd full-sized segment ACK'd           |4.2.3.2 |x| | | | |
  Receiver SWS-Avoidance Algorithm               |4.2.3.3 |x| | | | |
                                                 |        | | | | | |
Sending data                                     |        | | | | | |
  Configurable TTL                               |4.2.2.19|x| | | | |
  Sender SWS-Avoidance Algorithm                 |4.2.3.4 |x| | | | |
  Nagle algorithm                                |4.2.3.4 | |x| | | |
    Application can disable Nagle algorithm      |4.2.3.4 |x| | | | |
                                                 |        | | | | | |
Connection Failures:                             |        | | | | | |
  Negative advice to IP on R1 retxs              |4.2.3.5 |x| | | | |
  Close connection on R2 retxs                   |4.2.3.5 |x| | | | |
  ALP can set R2                                 |4.2.3.5 |x| | | | |1
  Inform ALP of  R1<=retxs<R2                    |4.2.3.5 | |x| | | |1
  Recommended values for R1, R2                  |4.2.3.5 | |x| | | |
  Same mechanism for SYNs                        |4.2.3.5 |x| | | | |
    R2 at least 3 minutes for SYN                |4.2.3.5 |x| | | | |
                                                 |        | | | | | |
Send Keep-alive Packets:                         |4.2.3.6 | | |x| | |
  - Application can request                      |4.2.3.6 |x| | | | |
  - Default is "off"                             |4.2.3.6 |x| | | | |
  - Only send if idle for interval               |4.2.3.6 |x| | | | |
  - Interval configurable                        |4.2.3.6 |x| | | | |
  - Default at least 2 hrs.                      |4.2.3.6 |x| | | | |
  - Tolerant of lost ACK's                       |4.2.3.6 |x| | | | |
                                                 |        | | | | | |
IP Options                                       |        | | | | | |
  Ignore options TCP doesn't understand          |4.2.3.8 |x| | | | |
  Time Stamp support                             |4.2.3.8 | | |x| | |
  Record Route support                           |4.2.3.8 | | |x| | |
  Source Route:                                  |        | | | | | |
    ALP can specify                              |4.2.3.8 |x| | | | |1
      Overrides src rt in datagram               |4.2.3.8 |x| | | | |
    Build return route from src rt               |4.2.3.8 |x| | | | |
    Later src route overrides                    |4.2.3.8 | |x| | | |
                                                 |        | | | | | |
Receiving ICMP Messages from IP                  |4.2.3.9 |x| | | | |
  Dest. Unreach (0,1,5) => inform ALP            |4.2.3.9 | |x| | | |
  Dest. Unreach (0,1,5) => abort conn            |4.2.3.9 | | | | |x|
  Dest. Unreach (2-4) => abort conn              |4.2.3.9 | |x| | | |
  Source Quench => slow start                    |4.2.3.9 | |x| | | |
  Time Exceeded => tell ALP, don't abort         |4.2.3.9 | |x| | | |
  Param Problem => tell ALP, don't abort         |4.2.3.9 | |x| | | |
                                                 |        | | | | | |
Address Validation                               |        | | | | | |
  Reject OPEN call to invalid IP address         |4.2.3.10|x| | | | |
  Reject SYN from invalid IP address             |4.2.3.10|x| | | | |
  Silently discard SYN to bcast/mcast addr       |4.2.3.10|x| | | | |
                                                 |        | | | | | |
TCP/ALP Interface Services                       |        | | | | | |
  Error Report mechanism                         |4.2.4.1 |x| | | | |
  ALP can disable Error Report Routine           |4.2.4.1 | |x| | | |
  ALP can specify TOS for sending                |4.2.4.2 |x| | | | |
    Passed unchanged to IP                       |4.2.4.2 | |x| | | |
  ALP can change TOS during connection           |4.2.4.2 | |x| | | |
  Pass received TOS up to ALP                    |4.2.4.2 | | |x| | |
  FLUSH call                                     |4.2.4.3 | | |x| | |
  Optional local IP addr parm. in OPEN           |4.2.4.4 |x| | | | |
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-------------------------------------------------|--------|-|-|-|-|-|--

FOOTNOTES:

(1)  "ALP" means Application-Layer program.