The Internet Link protocol or IL is a connection-based transport-layer protocol designed at Bell Labs originally as part of the Plan 9 operating system and is used to carry 9P. It is assigned the Internet Protocol number of 40. It is similar to TCP but much simpler.
Its main features are:
- Reliable datagram service
- In-sequence delivery
- Internetworking using IP
- Low complexity, high performance
- Adaptive timeouts
As of the Fourth Edition of Plan 9, 2003, IL is deprecated in favor of TCP/IP because it doesn't handle long-distance connections well.
Header
<syntaxhighlight lang="c">
struct IPIL
{
byte vihl; /* Version and header length */
byte tos; /* Type of service */
byte length[2]; /* packet length */
byte id[2]; /* Identification */
byte frag[2]; /* Fragment information */
byte ttl; /* Time to live */
byte proto; /* Protocol */
byte cksum[2]; /* Header checksum */
byte src[4]; /* Ip source */
byte dst[4]; /* Ip destination */
byte ilsum[2]; /* Checksum including header */
byte illen[2]; /* Packet length */
byte iltype; /* Packet type */
byte ilspec; /* Special */
byte ilsrc[2]; /* Src port */
byte ildst[2]; /* Dst port */
byte ilid[4]; /* Sequence id */
byte ilack[4]; /* Acked sequence */
};
</syntaxhighlight>
See also
- Fast Local Internet Protocol
References
Further reading
- —The original paper describing IL