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8 router discovery – PLANET WGS3-24000 User Manual

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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

Slot/Port

- Select the router interface for which data is to be configured.

Configurable Data

Advertise Mode

- Select enable or disable from the pulldown menu. If you select enable, Router Advertisements

will be transmitted from the selected interface.

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