Cisco Cisco IOS Software Release 12.2(27)SBC
ISSU and SSO—DHCP High Availability Features
Information About DHCP High Availability
5
Cisco IOS Release 12.2(31)SB22
ISSU and SSO—DHCP Proxy Client
The DHCP proxy client enables the router to obtain a lease for configuration parameters from a DHCP
server for a remote Point-to-Point Protocol (PPP) client. The DHCP proxy client that is ISSU and SSO
aware is able to request a lease from the DHCP server and the state of the lease is synchronized between
the active and standby RP.
server for a remote Point-to-Point Protocol (PPP) client. The DHCP proxy client that is ISSU and SSO
aware is able to request a lease from the DHCP server and the state of the lease is synchronized between
the active and standby RP.
illustrates the process.
Figure 3
DHCP Proxy Client Lease Synchronization
ISSU and SSO—DHCP ODAP Client and Server
The DHCP on-demand address pool (ODAP) client that is ISSU and SSO aware can request a lease for
a subnet from the DHCP ODAP server. After the DHCP ODAP server allocates the subnet to the client,
the state of the lease is synchronized between the active and standby RP through binding updates.
Following a switchover event, the DHCP ODAP client can continue to allocate IP addresses from the
same subnets and also continue to renew the subnets from the DHCP ODAP server.
a subnet from the DHCP ODAP server. After the DHCP ODAP server allocates the subnet to the client,
the state of the lease is synchronized between the active and standby RP through binding updates.
Following a switchover event, the DHCP ODAP client can continue to allocate IP addresses from the
same subnets and also continue to renew the subnets from the DHCP ODAP server.
illustrates
the process.
170566
CPE
BRAS
(DHCP Proxy Client)
DHCP Offer
DHCP Request
DHCP Ack
DHCP Discover
BNDUPD
Active
Standby
DHCP Request
DHCP Ack
BNDUPD
DHCP Release
BNDUPD
Lease created
Lease updated
Lease destroyed
DHCP
Server
PPP
DSLAM
PPP session setup
IPCP carries DHCP address to CPE
PPP session tear down
PPP session setup
IPCP carries DHCP address to CPE
PPP session tear down