Juniper JUNOSE SOFTWARE 10.2.2 - RELEASE NOTES 6-4-2010 Release Note page 26

JUNOSe 10.2.2 Release Notes
18
Known Behavior
When the DHCP relay agent application and the DHCP external server
application are configured in the same virtual router, using the ip
dhcp-external server-sync command on an unnumbered IP interface does not
function as expected. When you issue the ip dhcp-external server-sync
command in this configuration to create subscriber state information based on
lease renewals when the external DHCP server and the router are
unsynchronized, the router does not forward the ACK request from the DHCP
server to the client because there is no route. [Defect ID 88562]
When a bound DHCP client on a dynamic subscriber interface extends its IP
address lease by restarting the DHCP discovery process on its primary IP
interface instead of by initiating the DHCP renewal process on its dynamic
subscriber interface, the default behavior of the DHCP external server
application to preserve the client's dynamic subscriber interface was changed
in the following JUNOSe releases to delete and re-create the client's dynamic
subscriber interface:
Release 7.2.4p0-4 and all higher-numbered 7.2.x releases and patch
releases
Release 7.3.4 and all higher-numbered 7.3.x releases and patch releases
Release 8.0.4 and all higher-numbered 8.0.x releases and patch releases
Release 8.1.2 and all higher-numbered 8.1.x releases and patch releases
Release 8.2.3 and all 8.2.3 patch releases
Release 9.0.0 and all 9.0.0 patch releases
Release 9.0.1 and all 9.0.1 patch releases
Release 9.1.0 and all 9.1.0 patch releases
If you are upgrading the JUNOSe Software on the router from any of these
releases, you must explicitly issue the ip dhcp-external
recreate-subscriber-interface command to configure the router to continue to
delete and re-create the DHCP client's dynamic subscriber interface.
NOTE: The DHCP external server application is unsupported in JUNOSe Release
8.2.1 and JUNOSe Release 8.2.2.
DHCP external server may not be able to bind all DHCP clients when all of the
following conditions exist:
DHCP external server and either DHCP relay or relay proxy are configured
in separate virtual routers on an E320 router.
The client-facing and server-facing interfaces for DHCP external server and
either DHCP relay or relay proxy are configured on the same ES2 4G LM.
DHCP external server is configured to create dynamic subscriber interfaces.