Cisco Cisco ASR 5000
Page Throttling
▀ How it Works
▄ SGSN Administration Guide, StarOS Release 18
1. The SGSN initiates a paging message to identify the subscriber's current location.
2. The PMM application sends an indication to the Access layer whenever it wants to page the MS either for
signalling or data packets. Throttling of paging messages for UMTS is performed at the Access layer in the
Session Manager (SESSMGR). Throttling can be performed either at the Global or NSE level.
Session Manager (SESSMGR). Throttling can be performed either at the Global or NSE level.
3. For throttling at the global level, the RLF context is created at the Session Manager level and is maintained in the
Access layer.
4. Currently, the SGSN does not allow configuring the same RA in different RNCs across the IuPS services,
instead it allows only within the same IuPS service. For throttling at the RNC level, the RLF context is created
for each RNC and is maintained in the RNC control block of the Access layer in the Session Manager.
for each RNC and is maintained in the RNC control block of the Access layer in the Session Manager.
5. The Access layer collects the information about the subscriber to be paged and sends it to the RLF module for
throttling. The RLF template is configurable, and the RLF module performs the throttling function based on the
thresholds configured in the template.
thresholds configured in the template.
6. The RLF module applies the rate limiting algorithm based on the configured limits. It sends or queues paging
message based on the configured limits, once the maximum rate or the configured threshold is reached the
paging messages are dropped by the RLF module.
paging messages are dropped by the RLF module.
7. The Access layer registers the call-back functions which are used by RLF module to send the paging messages
out of SGSN.
Limitations
Listed below are the known limitations of the Page Throttling feature:
In the SGSN Global configuration mode "interface" command, the NSE-NAME (already existing) and RNC-
NAME (added as part of this feature) are not validated against the configuration under GPRS-SERVICE or
IuPS-SERVICE. This configuration is used only for the purpose of associating the paging-rlf-template for the
peer entity (either NSE/BSC or RNC). It is possible to change the ID to NAME mapping of both BSC and
RNC. The BSC/RNC ID is used for associating the paging-rlf-template as well as throttling the paging
messages internally even though the user can associate the paging-rlf-template using NAME explicitly.
IuPS-SERVICE. This configuration is used only for the purpose of associating the paging-rlf-template for the
peer entity (either NSE/BSC or RNC). It is possible to change the ID to NAME mapping of both BSC and
RNC. The BSC/RNC ID is used for associating the paging-rlf-template as well as throttling the paging
messages internally even though the user can associate the paging-rlf-template using NAME explicitly.
The rate limiting parameters for the rlf-template associated at global level should be configured in such a way
that it applies to all configured NSE and RNC's. The SGSN does not guarantee a uniform distribution of
message rate for each NSE/RNC while throttling at a global level.
message rate for each NSE/RNC while throttling at a global level.
Page throttling is applicable to all RNC's whenever the operator configures the same RNC-ID with different
PLMN-ID in different IuPS services. If the operator associates the Paging RLF template for that RNC-ID, the
SGSN starts page throttling for both the RNC's irrespective of the PLMN.
SGSN starts page throttling for both the RNC's irrespective of the PLMN.
No mechanism is present to identify if the operator associates the paging-rlf-template by either configured RNC
name or RNC identifier while generating the CLI for "show/save configuration". The paging-rlf-template CLI
is always generated with the RNC name if the operator configured the name mapping even though the
association is done using the RNC-ID otherwise the output is always generated with the RNC-ID.
is always generated with the RNC name if the operator configured the name mapping even though the
association is done using the RNC-ID otherwise the output is always generated with the RNC-ID.
Currently, the show output "show sgsn mode interface-mgmt-status" displays a maximum of "32" characters
(truncated value) of the name configured for both NSE/RNC and the RLF template name.
The SGSN does not support paging load limitation to the common RA paging initiated in the other access.
Whenever the operator removes the association of paging-rlf-template from a particular NSE/RNC and if the
page-limiting is already enabled at global level, all the queued messages in RLF context maintained for that
NSE/RNC will be flushed out by RLF and it does not accept any new paging messages for throttling. The RLF
context for that NSE/RNC will be cleaned up after all the messages in the queue flushed out. All the new
paging messages for that NSE/RNC will use the global RLF context for further rate-limiting.
NSE/RNC will be flushed out by RLF and it does not accept any new paging messages for throttling. The RLF
context for that NSE/RNC will be cleaned up after all the messages in the queue flushed out. All the new
paging messages for that NSE/RNC will use the global RLF context for further rate-limiting.