| IP option 3, Loose Source Route |
Description:
This option is used to route the internet datagram with info supplied by the source.
The loose source and record route (LSRR) option provides a means for the source of an internet datagram to supply routing information to be used by the gateways in forwarding the datagram to the destination, and to record the route information.
| MAC header | IP header | IP option 3 | Data |
IP Option 3:
| 00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Type | Length | Pointer | Route [] ::: | ||||||||||||||||||||||||||||
Type. 8 bits. Always set to 131.
| 00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 |
|---|---|---|---|---|---|---|---|
| C | Class | Option | |||||
C, Copy flag. 1 bit. Set to 1.
Indicates the option is to be copied into all fragments.Class. 2 bits. Set to 0.
The option is a control option.Option. 5 bits. Set to 3.
The IP option number.
Length. 8 bits.
Total length of the option in bytes.
Pointer. 8 bits.
Route []. Variable length.
An array of 32 bit IP addresses.
Host Implementation:
Router Implementation:
RFCs:
[RFC 791] Internet Protocol.