Cisco Intelligent Wireless Access Gateway, Руководство по настройке

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The process as part of iWAG SSO handling GTP checkpoints to the standby RP the information that is
necessary to create a copy of the session on the standby RP. Such an inactive copy of the session becomes
active when the standby RP becomes active.
When an iWAG mobility session with GTP tunneling is enabled using the SSO/ISSU feature, the Cluster
Control Manager on the active RP needs to wait for a few more components, including the GTP, to become
ready before checkpoint data collection, and polls these additional components for checkpoint data during
data collection. A very similar operation is performed on the standby RP as well. Although such additional
CPU consumption is per session, it is not expected to be too heavy since processing in each of these components
should include the time spent on a few data structure lookups and memory-copying operations.
During ISSU SIP and SPA upgrade, there is traffic interruption. To avoid session disconnect because of
dropped echo messages during such traffic interruption, a user has the following options:
• Option 1 (preferred):
1 Disable the echo messages on the iWAG and GGSN for the duration of the ISSU.
2
Re-enable the echo messages after ISSU is completed on the iWAG and GGSN.
• Option 2: Extend the t3 and n3 configurations to exceed the expected traffic interruption. The traffic
interruption characterized in the Cisco IOS XE Release 3.10S is 127 seconds. Hence, we recommend
the following t3 and n3 settings (t3_response: 1 and n3_request: 7, resulting in 127 seconds on both the
iWAG and GGSN) but the duration of the traffic interruption may depend on the types of SIPs and SPAs
and how loaded the router is. If traffic interruption exceeds the configured t3 and n3 limits, the session
is disconnected.
Enabling SSO Support for the GTP
This section describes how to enable SSO support for the GTP on the Cisco ASR 1000 Series Aggregation
Services Routers.
SUMMARY STEPS
1. enable
2.
configure terminal
3. redundancy
4. mode SSO
DETAILED STEPS
Purpose Command or Action
Enables the privileged EXEC mode. enable Step 1
Example:
Router> enable
Enter your password, if prompted.
Intelligent Wireless Access Gateway Configuration Guide
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iWAG SSO Support for GTP
Enabling SSO Support for the GTP