PLANET WGS3-24240 - Manual (Page 297)

User’s Manual of WGS3-24000 / WGS3-24240
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• Requests Relayed The total number of BOOTP/DHCP requests forwarded to the server since the
last time the switch was reset.
• Packets Discarded - The total number of BOOTP/DHCP packets discarded by this Relay Agent since
the last time the switch was reset.
4.6.8 Router Discovery
The Router Discovery is not a routing protocol but a Router Discovery Protocol. The function Router Discovery allows
neighboring routers to be found from ICMP Router Advertisement messages. It also be named as IRDP (ICMP Router
Discovery Protocol). – implemented as defined in RFC-1256.
The ICMP router discovery messages are called "Router Advertisements" and "Router Solicitations". Each router periodically
multicasts a Router Advertisement from each of its multicast interfaces, announcing the IP address(es) of that interface.
Hosts discover the addresses of their neighboring routers simply by listening for advertisements. When a host attached to a
multicast link starts up, it may multicast a Router Solicitation to ask for immediate advertisements, rather than waiting for the
next periodic ones to arrive; if (and only if) no advertisements are forthcoming, the host may retransmit the solicitation a small
number of times, but then must desist from sending any more solicitations.
Any routers that subsequently start up, or that were not discovered because of packet loss or temporary link partitioning, are
eventually discovered by reception of their periodic (unsolicited) advertisements. (Links that suffer high packet loss rates or
frequent partitioning are accommodated by increasing the rate of advertisements, rather than increasing the number of
solicitations that hosts are permitted to send.)
4.6.8.1 Router Discovery Configuration
Figure 4-6-41 Router Discovery Configuration
Selection Criteria