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Removing routes when DHCP clients release their DHCP-assigned addresses or
when the addresses expire
When a DHCP client sends a request to an external DHCP server, the relay proxy
receives the request and forwards it to the external DHCP server. The relay proxy
then sends the DHCP server’s response back to the client. This process is similar to
that used by the DHCP relay component. The DHCP client views the relay proxy as
a DHCP server, and the DHCP server sees the relay proxy as a DHCP relay agent.
To DHCP clients, there is no difference when they use a DHCP relay or a DHCP relay
proxy. However, the DHCP relay proxy differs from the DHCP relay in how client
address renewals and releases are handled:
■
With the DHCP relay proxy, DHCP clients communicate with the relay proxy to
renew and release addresses.
■
With the DHCP relay, DHCP clients communicate directly with the DHCP server
to renew and release addresses.
A major benefit of the relay proxy configuration is that the E Series router is kept
informed of the status of a DHCP client’s address. When addresses are released by
clients, the router removes the installed host route for that client. In the DHCP relay
configuration, the router does not know when addresses have been renewed or
released; the host routes that are no longer needed are still unavailable.
For additional information on managing client bindings, see “Viewing and Deleting
DHCP Client Bindings” on page 460.
Selecting the DHCP Server Response
Similar to the DHCP relay, the DHCP relay proxy enables you to specify up to five
DHCP servers to provide address and configuration information for a DHCP client.
As an added benefit over the relay, when using multiple DHCP external servers, you
can configure how the DHCP relay proxy determines which offer to send to the DHCP
client. You can configure the DHCP relay proxy to use either the single best offer or
the first offer it receives from the DHCP servers.
If there are multiple offers, the DHCP relay proxy selects the final offer based on the
following priorities:
1.
The offer that contains the IP address requested by the DHCP client.
2.
The offer that contains an IP address on the same subnetwork as the requested
IP address.
3.
The offer that has the longest lease time.
If you have enabled the optional select-first-offer feature, the DHCP relay proxy
immediately uses the first offer that it receives from any DHCP server.
Behavior for Bound Clients and Address Renewals
When a DHCP client is already bound to an IP address or is renewing the lease on
its IP address, DHCP relay proxy unicasts DHCP ACK and DHCP NAK replies to the
514
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Configuring DHCP Relay Proxy
JUNOSe 11.0.x Broadband Access Configuration Guide
Содержание JUNOSE 11.0.X MULTICAST ROUTING
Страница 6: ...vi...
Страница 28: ...xxviii Table of Contents JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 36: ...xxxvi List of Tables JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 42: ...2 Managing Remote Access JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 204: ...164 Managing RADIUS and TACACS JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 274: ...234 CLI Commands Used to Modify RADIUS Attributes JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 292: ...252 Monitoring RADIUS Relay Server JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 336: ...296 RADIUS Client Terminate Reasons JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 368: ...328 Managing L2TP JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 408: ...368 Configuring the Weighted Load Balancing Method JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 444: ...404 PPP Accounting Statistics JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 492: ...452 Monitoring Operational Status within the Current VR Context JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 494: ...454 Managing DHCP JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 510: ...470 DHCP Local Server Configuration Tasks JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 528: ...488 Configuring the Router to Work with the SRC Software JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 556: ...516 Configuring DHCP Relay Proxy JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 616: ...576 Managing the Subscriber Environment JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 632: ...592 Subscriber Management Configuration Examples JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 636: ...596 Monitoring Active IP Subscribers Created by Subscriber Management JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 672: ...632 Monitoring Active IP Subscribers Created by Subscriber Management JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 674: ...634 Managing Subscriber Services JUNOSe 11 0 x Broadband Access Configuration Guide...
Страница 767: ...Part 7 Index Index on page 729 Index 727...
Страница 768: ...728 Index JUNOSe 11 0 x Broadband Access Configuration Guide...