Router Discovery Messages - Novell NETWARE 6-DOCUMENTATION Manual

Router Discovery Messages

ICMP Router Advertisement Message
ICMP Router Solicitation Message
Router Discovery Multicast Address
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NetWare TCP/IP Administration Guide
Forwarding is disabled, the Router Discovery Protocol will send Router
Solicitation Messages. these messages are explained in the next section.
The two message types that are used by the Router Discovery Protocol to
communicate between hosts and routers are discussed in the following
sections.
The ICMP Router Advertisement Message is ICMP message type 9. This
message is used by routers to advertise their presence on the network and is
broadcast or multicast to all hosts on the network.
This message type carries the IP address of the router and its preference level.
Hosts use the preference level to determine which router to use for forwarding.
The router with the highest preference becomes the default router. A value of
0x80000000 indicates the router is not to be used. Routers with this value are
used only when other routers send ICMP Redirect messages to the host.
The ICMP Router Solicitation Message is ICMP message type 10. Hosts use
this message to solicit router advertisements from all participating routers on
the network.
Router Discovery uses two IP multicast addresses. The IP address 224.0.0.1 is
reserved to multicast the Router Advertisement Message to the hosts. The IP
address 224.0.0.2 is reserved to multicast the Router Solicitation Message to
the routers. If the network does not support multicast, then broadcast address
255.255.255.255 is used for both the Router Advertisement and Router
Solicitation messages.