IP option 3, Loose Source Route

Description Glossary RFCs Publications Obsolete RFCs


Protocol suite: TCP/IP.
Protocol type:Connectionless network layer protocol.
Option length: Variable length.
Host implementation:
Router implementation:
Links: IANA: IP option numbers.

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:

0001020304050607 0809101112131415 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.

C Class Option

C, Copy flag. 1 bit. Set to 1.
Indicates the option is to be copied into all fragments.

Class. 2 bits. Cleared 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.



[RFC 791] Internet Protocol.


Obsolete RFCs:

Description Glossary RFCs Publications Obsolete RFCs