perm filename IMPHDR.TXT[SS,SYS] blob
sn#804877 filedate 1986-01-20 generic text, type C, neo UTF8
COMMENT ā VALID 00004 PAGES
C REC PAGE DESCRIPTION
C00001 00001
C00002 00002 Format of an IMP message header (32 bit words)
C00007 00003 Format of an IMP message header (36 bit words)
C00011 00004 TCP state diagram (from RFC 793):
C00017 ENDMK
Cā;
Format of an IMP message header (32 bit words)
(In 1822, IMP-host header bits are numbered 1-96. Here they are
numbered starting at 0 in word 0.)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------+-------+---------------+-------+-+-----+---------------+
0 |unused | New | Destination |unused |T|Ldr | Message |
| | Format| Network | |r|Flags| Type |
+-------+-------+---------------+-------+-+-----+---------------+
1 | Handling | Destination | Destination |
| Type | Host | IMP |
+---------------+-------+-------+-------------------------------+
2 | Message ID |Sub- | Message Length |
| |Type | |
+-----------------------+-------+-------------------------------+
Internet (IP) header (IHL = Internet header length, in 32-bit words)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------+-------+---------------+-------------------------------+
3 |Version| IHL |Type of Service| Total Length |
+-------+-------+---------------+-----+-------------------------+
4 | Identification |Flags| Fragment Offset |
+---------------+---------------+-----+-------------------------+
5 | Time to Live | Protocol | Header Checksum |
+---------------+---------------+-------------------------------+
6 | Source Address |
+---------------------------------------------------------------+
7 | Destination Address |
+-----------------------------------------------+---------------+
| Options | Padding |
+-----------------------------------------------+---------------+
TCP header
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
8 | Source Port | Destination Port |
+-------------------------------+-------------------------------+
9 | Sequence Number |
+---------------------------------------------------------------+
10 | Acknowledgement Number |
+-------+-----------+-+-+-+-+-+-+-------------------------------+
| Data | |U|A|P|R|S|F| |
11 | Offset| Reserved |R|C|S|S|Y|I| Window |
| | |G|K|H|T|N|N| |
+-------+-----------+-+-+-+-+-+-+-------------------------------+
12 | Checksum | Urgent Pointer |
+-------------------------------+---------------+---------------+
| Options | Padding |
+-----------------------------------------------+---------------+
13 | data |
+---------------------------------------------------------------+
(IP and TCP options are optional. Padding fills to 32-bit boundary.)
Format of an IMP message header (36 bit words)
(assuming no options)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-------+-------+---------------+-------+-+-----+---------------+-------+
0 |unused | New | Destination |unused |T|Ldr | Message |Handling
| | Format| Network | |r|Flags| Type |Type
+-------+-------+-------+-------+-------+-+-----+-------+-------+-------+
1 Handling| Destination | Destination | Message ID
Type | Host | IMP |
+-------+-------+-------+-----------------------+-------+-------+-------+
2 Message|Sub- | Message Length |IP | IHL |Type of
ID |Type | |Version| |Service
+-------+-------+-----------------------+-------+-------+-------+-------+
3 Type of| Total Length | Identification |
Service| | |
+-----+-+-----------------------+-------+-------+---------------+-------+
4 |Flags| Fragment Offset | Time to Live | Protocol |Cksum
+-----+-----------------+-------+---------------+---------------+-------+
5 IP Header Checksum | Source Address
+---------------+-------+-----------------------------------------------+
6 Source Address | Destination Address
+-------+-------+-----------------------+-------------------------------+
7 Dest Adr| Source Port | Destination Port |
+-------+-------------------------------+-----------------------+-------+
8 | Sequence Number |ACK No.
+-------------------------------------------------------+-------+-------+
9 Acknowledgement Number | Data | Reser-
| Offset| ved
+---+-+-+-+-+-+-+-------------------------------+-------+-------+-------+
|U|A|P|R|S|F| |
10 Rsvd|R|C|S|S|Y|I| Window | TCP checksum
|G|K|H|T|N|N| |
+---+-+-+-+-+-+-+-----------------------+-------+-----------------------+
11 Cksum | Urgent Pointer | (beginning of data)
+-------+-------------------------------+-------------------------------+
TCP state diagram (from RFC 793):
September 1981
Transmission Control Protocol
Functional Specification
+---------+ ---------\ active OPEN
| CLOSED | \ -----------
+---------+<---------\ \ create TCB
| ā \ \ snd SYN
passive OPEN | | CLOSE \ \
------------ | | ---------- \ \
create TCB | | delete TCB \ \
V | \ \
+---------+ CLOSE | \
| LISTEN | ---------- | |
+---------+ delete TCB | |
rcv SYN | | SEND | |
----------- | | ------- | V
+---------+ snd SYN,ACK / \ snd SYN +---------+
| |<----------------- ------------------>| |
| SYN | rcv SYN | SYN |
| RCVD |<-----------------------------------------------| SENT |
| | snd ACK | |
| |------------------ -------------------| |
+---------+ rcv ACK of SYN \ / rcv SYN,ACK +---------+
| -------------- | | -----------
| x | | snd ACK
| V V
| CLOSE +---------+
| ------- | ESTAB |
| snd FIN +---------+
| CLOSE | | rcv FIN
V ------- | | -------
+---------+ snd FIN / \ snd ACK +---------+
| FIN |<----------------- ------------------>| CLOSE |
| WAIT-1 |------------------ | WAIT |
+---------+ rcv FIN \ +---------+
| rcv ACK of FIN ------- | CLOSE |
| -------------- snd ACK | ------- |
V x V snd FIN V
+---------+ +---------+ +---------+
|FINWAIT-2| | CLOSING | | LAST-ACK|
+---------+ +---------+ +---------+
| rcv ACK of FIN | rcv ACK of FIN |
| rcv FIN -------------- | Timeout=2MSL -------------- |
| ------- x V ------------ x V
\ snd ACK +---------+delete TCB +---------+
------------------------>|TIME WAIT|------------------>| CLOSED |
+---------+ +---------+
TCP Connection State Diagram
Figure 6.
[Page 23]