HP 600 Series, Services And Applications

Page: 139 / 316

The relay agent sends the Bootrequest either to specifically configured
addresses or to the broadcast IP address. When the Bootp server receives
the relayed request, it sends the Bootreply to the relay agent that is adjacent
to the client. The adjacent Bootp relay agent then sends the Bootreply to the
client’s station and IP addresses on the interface from which the Bootrequest
was received.
Note that the Bootp relay agent functionality need not be turned on in all the
routers between the client and server. The router that is adjacent to the
client must be a relay agent. If that adjacent relay agent has a configured set
of Bootrequest destinations that are either specific server addresses or
subnet addresses, then it is the only router that needs the relay agent
functionality. See figure 15. If the adjacent relay agent does not have either
server or subnet addresses configured, then the Bootrequest is sent out
through all of the adjacent router’s interfaces, and is addressed to the All
Hosts Broadcast for each interface. See figure 16. To allow these Bootre-
quests to be forwarded to the server, each router in the path between the
client and server must be a Bootp relay agent.
Figure 15. Bootrequest Relay with Specific Server or Subnet
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Internet Protocol Routing Service
BootP and DHCP
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