Computer Networks · TEE · formulas
Protocol facts worth writing accurately
TEE formulas, definitions and full forms
TEE · Complete six-unit quick reference · current syllabus 702AI0C023
| Topic | Exact fact |
|---|---|
| OSI / TCP-IP | Seven OSI layers; four TCP/IP layers here; five-layer teaching model splits link |
| CRC | Zero syndrome means no error detected, not certainty of no errors |
| GBN / SR ACK | This course: GBN ACK k=next expected; SR ACK k=individual frame accepted |
| IPv4 / IPv6 | 32-/128-bit addresses; IPv6 base header 40 bytes; no IPv6 broadcast |
| UDP / TCP / SCTP | UDP 8-byte header; TCP minimum 20; SCTP common 12 plus chunks |
| TCP data | Bytes counted; ACK next expected; SYN and FIN each consume one; pure ACK none |
| RIP | Metric 16 means unreachable; 15 is highest reachable hop metric |
| OSPF | Hello, Database Description, Link State Request, Link State Update, Link State Acknowledgment |
| HTTP | Default plain HTTP port 80; HTTPS commonly 443; HTTP/3 uses QUIC/UDP |
| DNS | Classic DNS uses UDP and TCP 53, not UDP only |
| FTP | Control TCP 21; active data traditionally server 20; passive port negotiated |
| SMTP | Server relay TCP 25; submission commonly 587; SMTP does not retrieve inboxes |
| Token shortage | Shaper delays; policer applies mark/drop policy; behaviour must be specified |