RFC 3442 (rfc3442) - Page 3 of 9
The Classless Static Route Option for Dynamic Host Configuration Protocol (DHCP) version 4
Alternative Format: Original Text Document
RFC 3442 Classless Static Route Option for DHCPv4 December 2002
This document also uses the following terms:
"DHCP client"
DHCP client or "client" is an Internet host using DHCP to
obtain configuration parameters such as a network address.
"DHCP server"
A DHCP server or "server" is an Internet host that returns
configuration parameters to DHCP clients.
"link"
Any set of network attachment points that will all receive a
link-layer broadcast sent on any one of the attachment points.
This term is used in DHCP because in some cases more than one
IP subnet may be configured on a link. DHCP uses a local-
network (all-ones) broadcast, which is not subnet-specific, and
will therefore reach all nodes connected to the link,
regardless of the IP subnet or subnets on which they are
configured.
A "link" is sometimes referred to as a broadcast domain or
physical network segment.
Classless Route Option Format
The code for this option is 121, and its minimum length is 5 bytes.
This option can contain one or more static routes, each of which
consists of a destination descriptor and the IP address of the router
that should be used to reach that destination.
Code Len Destination 1 Router 1
+-----+---+----+-----+----+----+----+----+----+
| 121 | n | d1 | ... | dN | r1 | r2 | r3 | r4 |
+-----+---+----+-----+----+----+----+----+----+
Destination 2 Router 2
+----+-----+----+----+----+----+----+
| d1 | ... | dN | r1 | r2 | r3 | r4 |
+----+-----+----+----+----+----+----+
In the above example, two static routes are specified.
Lemon, et. al. Standards Track