IP Pool Sharing Protocol


IP Pool Sharing Protocol
 
 
This chapter provides information on configuring an enhanced, or extended, service. The product administration guides provide examples and procedures for configuration of basic services on the system. It is recommended that you select the configuration example that best meets your service model, and configure the required elements for that model before using the procedures in this chapter.
Sections in this chapter include:
 
 
Overview
The IP Pool Sharing Protocol (IPSP) is a protocol that system-based HA services can use during an offline-software upgrade to avoid the assignment of duplicate IP addresses to sessions while allowing them to maintain the same address, and to preserve network capacity.
 
In order for IPSP to be used, at least two system-based HAs with identical configurations must be present on the same LAN. IPSP uses a primary & secondary model to manage the IP pools between the HAs. When used, this protocol ensures the following:
The protocol is enabled at the interface level. Each system-based HA must have an IPSP-enabled interface configured in the same context as the HA service for this protocol to function properly.
 
Primary HA Functionality
The primary HA is the system that is to be upgraded. It performs the following functions for IPSP:
 
 
For graceful termination conditions (e.g. an administrative user issues the reload command), sends a termination message to the secondary HA causing it to assume the responsibilities of the primary HA until the primary is available again.
 
Secondary HA Functionality
The secondary HA is the system that takes over Mobile IP sessions from the primary HA that is being upgraded. It performs the following functions for IPSP:
 
 
For graceful termination conditions (e.g. an administrative user issues the reload command), it notifies the primary HA that it is going out of service
 
Requirements, Limitations, & Behavior
 
 
 
How IPSP Works
IPSP operation requires special configuration in both the primary and secondary HAs. As mentioned previously, both HAs must have identical configurations. This allows the secondary HA to process sessions identically to the primary when the primary is taken offline for upgrade.
Configuration must also be performed on the AAA server. Whereas subscriber profiles on the AAA server originally directed sessions to the primary HA, prior to using IPSP, subscriber profiles must be re-configured to direct sessions to the secondary HA.
There are two scenarios in which IPSP takes effect:
New sessions: Once IPSP is configured, new sessions are directed to a secondary HA (HA2) allowing the primary HA to go through a software upgrade without degrading network capacity. The secondary HA requests addresses from the primary HA’s (HA1) pools as needed. As the addresses are allocated, they are busied out on the primary HA. This procedure is displayed below.
Session handoffs: Once IPSP is configured, sessions originally registered with the primary HA (HA1) are re-registered with the secondary HA (HA2). To ensure the session is assigned the same IP address, the secondary HA requests the address from the primary HA. The primary HA verifies the binding and releases it to the secondary HA which, in turn, re-assigns it to the session. As the addresses are allocated, they are busied out on the primary HA. This procedure is displayed below.
 
IPSP Operation for New Sessions
The following figure and text describe how new sessions are handled when IPSP is enabled.
 
IPSP Operation for New Sessions
IPSP Operation for New Sessions Description
 
IPSP Operation for Session Handoffs
The following figure and text describe how session handoffs are handled when IPSP is enabled.
 
IPSP Operation for Session Handoffs
IPSP Operation for Session Handoffs Description
 
Configuring IPSP Before the Software Upgrade
Configuring IPSP requires changes to the primary HA (the HA on which the software upgrade is to occur), the secondary HA (the HA to which subscribers sessions are to be directed), and the AAA server.
This section provides information and instructions for configuring IPSP before the software upgrade.
Important: This section provides the minimum instruction set for configuring IPSP on the system. For more information on commands that configure additional parameters and options, refer to the IPSP Configuration Mode Commands chapter in the Command Line Interface Reference.
To enable the IP pool sharing during software upgrade:
Step 1
Step 2
Configure an interface on the system for use by IPSP according to the instructions found in the Creating and Configuring Ethernet Interfaces and Ports section of the System Administration Guide.
Step 3
Step 4
Perform the boot system priority and SPC/SMC card synchronization as described in Off-line Software Upgrade section in the System Administration Guide.
Step 5
Step 6
Verify your ACL configuration by following the steps in the Verifying the IPSP Configuration section.
Step 7
Step 8
Save your configuration as described in the Saving Your Configuration chapter.
 
Configuring the AAA Server for IPSP
For subscriber session establishment, the AAA server provides the IP address of the HA that is to service the session. This information exists in the 3GPP2_MIP_HA_Address RADIUS attribute configured for the subscriber.
Because the primary HA has been responsible for facilitating subscriber sessions, its IP address is the one configured via this attribute. For IPSP however, the attribute configuration must change in order to direct sessions to the secondary HA.
To do this, reconfigure the 3GPP2_MIP_HA_Address RADIUS attribute for each subscriber on the AAA server with the IP address of the secondary HA.
The precise instructions for performing this operation vary depending on the AAA server vendor. Refer to the documentation for your AAA server for more information.
 
Enabling IPSP on the Secondary HA
The secondary HA is the alternate HA that is to take responsibility while the primary HA is upgraded.
Important: This section provides the minimum instruction set for configuring IPSP on the system. For more information on commands that configure additional parameters and options, refer to the IPSP Configuration Mode Commands chapter in Command Line Interface Reference.
Use the following example to enable the IPSP on secondary HA:
configure
  context <ipsp_ctxt_name> [ -noconfirm ]
     interface <ipsp_if_name>
        pool-share-protocol primary <pri_ha_address> [ mode {active | inactive | check-config } ]
           dead-interval <dur_sec>
           end
Notes:
 
ipsp_if_name is the name of the interface on which you want to enable IPSP.
 
Enabling IPSP on the Primary HA
The primary HA is the HA that is to be upgraded.
Important: This section provides the minimum instruction set for configuring IPSP on the system. For more information on commands that configure additional parameters and options, refer to the IPSP Configuration Mode Commands chapter in the Command Line Interface Reference.
Use the following example to enable the IPSP on primary HA:
configure
  context <ipsp_ctxt_name> [ -noconfirm ]
     interface <ipsp_if_name>
        pool-share-protocol secondary <sec_ha_address> [ mode {active | inactive | check-config } ]
           dead-interval <dur_sec>
           end
Notes:
 
ipsp_if_name is the name of the interface on which you want to enable IPSP.
Important: Once this configuration is done, the primary HA begins to hand responsibility for sessions and release IP addresses to the secondary HA. Prior to performing the software upgrade, all IP addresses must be released. When IPSP has released all IP pool addresses from the primary HA an SNMP trap (starIPSPAllAddrsFree) is triggered.
 
Verifying the IPSP Configuration
These instructions are used to verify the IPSP configuration.
Step 1
 
show ip ipsp
The output of this command provides the list of used addresses and released addresses. The system will send the starIPSPAllAddrsFree trap once all IP addresses are released. When the value in the Used Addresses column reaches 0 for all IP pools listed, then the primary HA sends the SNMP trap and notifies the secondary HA to take over as the primary HA.
 
Configuring IPSP After the Software Upgrade
If desired, IP pool addresses can be migrated from the original secondary HA back to the original primary HA once the upgrade process is complete.
Important: It is important to note that the HA that was originally designated as the secondary is now functioning as the primary HA. Conversely, the HA that was originally designated as the primary is now functioning as the secondary.
In order to migrate the addresses, both HAs and the AAA server must be configured according to the instructions in this section.
This section provides information and instructions for configuring IPSP after the software upgrade.
Important: This section provides the minimum instruction set for configuring IPSP on the system. For more information on commands that configure additional parameters and options, refer IPSP Configuration Mode Commands chapter in Command Line Interface Reference.
To enable the IP pool sharing after software upgrade:
Step 1
Step 2
Step 3
Step 4
Step 5
Verify your ACL configuration by following the steps in the Verifying the IPSP Configuration section.
Step 6
Save your configuration as described in the Saving Your Configuration chapter.
 
Disabling IPSP
Once all IP addresses on the primary HA have been released, IPSP must be disabled on both the primary and secondary HAs.
 
Caution: Prior to disabling IPSP, ensure that the primary HA has released all IP addresses to secondary HA.
Follow the instructions in this section to disable IPSP on primary and secondary HA after migration of all IP addresses.
Important: This section provides the minimum instruction set for disabling IPSP on the HAs. For more information on commands, refer to the IPSP Configuration Mode Commands chapter in the Command Line Interface Reference.
Use the following example to enable the IPSP on primary/secondary HA:
configure
  context <ipsp_ctxt_name> [ -noconfirm ]
     interface <ipsp_if_name>
        no pool-share-protocol
        end
Notes:
 
ipsp_if_name is the name of the interface on which you want to disable IPSP.
 

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