Overview
The hard disk was introduced in the ASR 5500 platform to add storage capability. The first application is used in CDMA environments to increase buffering for I/O between the gateway and L-ESS to alleviate tight linkage required to avoid record loss due to overrun on the ASR 5500 PSC buffers.
The External Storage System (ESS) is a high availability, fault tolerant, redundant solution for short-term storage of files containing detail records (UDRs/EDRs/FDRs (xDRs)). To avoid loss of xDRs on the chassis due to overwriting, deletion, or unforeseen events such as power or network failure or unplanned chassis switchover, xDRs are off-loaded to ESS for storage and analysis to avoid loss of charging and network analysis information contained in the xDRs. The xDR files can be pulled by the external storage from the chassis, or the chassis can push the xDR files to the external storage using SFTP protocol. In the Push mode, the external storage URL to which the xDR files need to be transferred to is specified. The configuration allows a primary and a secondary server to be configured. Configuring the secondary server is optional. Whenever a file transfer to the primary server fails for four consecutive times, the files will be transferred to the secondary server. The system running with ECS stores xDRs on an external storage, and the billing system collects the xDRs form the external storage and correlates them with the AAA accounting messages using 3GPP2-Correlation-IDs (for PDSN) or Charging IDs (for GGSN).
This release now supports purging/deleting xDR records based on time or volume limit to restrict hard-disk space usage for charging records. When configured, old records can be deleted based on specified storage or time limits.
The second application is intended for UMTS environment. Records generated on ASR 5500 are sent through UDP to an external storage application running on possibly clustered SUN servers utilizing shared storage. In parallel, records are sent over GTPP to a CGF. In addition to (e)GCDRs, the hard disk supports SCDRs and MCDRs generated by SGSN.
Important |
The hard disk is not designed to support all features supported by the external storage application and not intended to replace this application in all situations. |
The hard disk is useful for other applications:
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Store the Content Filtering static ratings database instead of using FLASH; valuable for other users including recovery scenarios.
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IPMS
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Large volume firewall and other DPI information such as applications/particular user, and users/bay station heretofore not store-able embedded.
The hard drive serves a number of uses in providing storage for various records generated by the mobile gateway that formerly require buffering or treatment outside of the gateway, necessitating purchase and operation of auxiliary servers. For 3GPP2 accounts the hard disk is an enhancement to service, and not a replacement. The hard drive is required to provide non-volatile storage in the ASR 5500. For 3GPP accounts the hard disk can be used instead of external storage in networks where storage and record formatting needs can be met by the hard disk. The communication link between the ASR 5500 and external storage is removed. GTPP continues to be supported. Files can be accessed by either GTPP (streaming) or sFTP (file I/O), but not both. At the same time, different files can be accessed by GTPP or sFTP.
Benefits
The HDD functionality provides an additional level of protection to the wireless operator by ensuring the charging records are preserved in case the Charging Gateway (CGF) goes down or loses connectivity with the ASR 5500 gateway. At the same time, this was implemented in a way that does not require any addition or modification to the existing mediation/billing systems.
Supported Records on HDD
This section describes the various records supported on the HDD:
Accounting Request Records (ACR)
The Accounting Request Records are types of CDRs that contain offline charging information generated by the Diameter Rf interface. If all the Diameter servers configured in a group are down, ACRs are written to files in formats supported by the external node and stored on the HDD. These files are created when the chassis does not have connection with the CDF. From the HDD, ACR files can be pushed/pulled using FTP/SFTP protocols.
Important |
ACRs are supported in 10.0 and later releases. |
In StarOS releases prior to 12.3, in the standby chassis if HDD is configured and if the HDD profile status is unavailable, the pending Diameter accounting requests will be removed. Release 12.3 onwards, when HDD is configured in the standby chassis, irrespective of HDD profile status, the Diameter accounting requests will be retried to HDD until it successfully writes in to HDD. Any misconfiguration of HDD can result in Diameter accounting requests being piled up in to accounting archive list in the standby chassis. The only way to clean up the list can be either un-configure the HDD or configure active HDD properly.
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RAM-disk: /records/acr/<policy_name>/
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HDD: /hd-raid/data/records/acr/<policy_name>/
File Formats: Currently, file format1 to format10 are supported.
Supported Products: HSGW, P-GW, S-GW
Charging Data Records (CDR)
A Charging Data Record is a formatted collection of information about a chargeable event. The CDRs generated by GGSN/SGSN are sent to an external node for storage. CDRs are written to files in formats supported by the external node and stored on the HDD. From the HDD, CDR files can be pushed/pulled using FTP/SFTP protocols.
For information on how to configure push functionality, refer to the Configuring CDR Push section in this chapter.
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RAM-disk: /records/cdr/<gtpp_group_name><vpn_id>/
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HDD: /hd-raid/data/records/cdr/<gtpp_group_name><vpn_id>/
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RAM-disk: /records/cdr/hdd_sec_stor_<gtpp-group-name><vpn-id>/
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HDD: /hd-raid/data/records/cdr/hdd_sec_stor_<gtpp-group-name><vpn-id>/
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RAM-disk: /records/cdr/<gtpp-group-name>_<context-name>/
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HDD: /hd-raid/records/cdr/<gtpp-group-name>_<context-name>/
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RAM-disk: /records/cdr/hdd_sec_stor_<gtpp-group-name>_<context-name>/
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HDD: /hd-raid/records/cdr/hdd_sec_stor_<gtpp-group-name>_<context-name>/
File Formats: The GSS file formats, Custom1 to Custom8 are supported.
Supported Products: ePDG, GGSN, SGSN, P-GW, S-GW
Diameter Records
The Diameter Records contain CCR messages generated by the Diameter Gy interface. In cases where the Assume-Positive interim-quota is allocated, and CCR-T is not reported/answered, the CCR-T message is written to a local file, and saved in the HDD. This local file and directory information can be fetched and parsed to account for the lost bytes/usage. The retrieval of the file can be done with the PULL mechanism.
Important |
This feature requires a valid license to be installed prior to configuring this feature. Contact your Cisco account representative for more information on the licensing requirements. |
Important |
Diameter records are supported in 19 and later releases. |
When the diameter hdd CLI command is configured in the Credit Control Group Configuration mode, the Gy application sends the failed CCR-T messages to the CDR module for storing in the HDD. For more information, see the Command Line Interface Reference guide.
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RAM-disk: /records/diameter/
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HDD: /hd-raid/data/records/diameter/
Supported Products: HA, P-GW
Event Data Records (EDR)
The Event Data Records are responsible for definition, generation, and offloading of EDRs generated in the system (as a result of occurrence of an event) to the external billing system. EDRs are basically used for content billing purposes, wherein it is required that a different charging unit be employed for different types of content e.g. HTTP, SMTP, MMS, etc. EDRs are a type of usage records that are configurable by the operator. EDRs are generated per flow subject to available configuration.
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RAM-disk: /records/edr/
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HDD: /hd-raid/data/records/edr/
File Formats: In this release, EDRs are supported in the Comma Separated Values (CSV) format.
Supported Products: ECS and other products/features using ECS
Event Records
The Event reporting is a mechanism using which subscriber activities like session creation/deletion, bearer creation/modification/update/deletion are reported to the external server (RTT server). The event report logs assist network operators in maintaining and troubleshooting the network. The event records are stored as files in the HDD and these files are later SFTPd to the external RTT server. To store the event records in the form of files, compress the event record file using the Call Detail Records Module (CDRMOD) which provides support for collecting, storing, and compressing the event records.
Important |
Event Records are supported in 12.2 and later releases. |
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RAM-disk: /records/event/
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HDD: /hd-raid/data/records/event/
File Formats: In this release, Event Records are supported in the Comma Separated Values (CSV) format.
Supported Products: SGSN, S-GW
Reporting Event Data Records (REDR)
Reporting Event Data Records are a type of CDRs that contain EDRs generated on flow end conditions, that is reporting flow end EDRs and HTTP transaction EDRs. REDR records are written to files in formats supported by the external node and stored in the HDD. From the HDD, REDR records can be pushed/pulled using FTP/SFTP protocols.
Important |
REDRs are supported in 12.2 and later releases. |
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RAM-disk: /records/redr/
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HDD: /hd-raid/data/records/redr/
File Formats: In this release, REDRs are supported in the Comma Separated Values (CSV) format.
Supported Products: ECS and other products/features using ECS
Usage Data Records (UDR)
The Usage Data Records contain accounting information related to a specific mobile subscriber. UDRs are generated and stored on the system as records in CSV format (comma separated values). The CDR subsystem in conjunction with the External Storage Server (ESS) are responsible for offloading of UDRs. UDRs are generated per content type. The fields required as part of usage data records are configurable and stored in the System Configuration Task (SCT). UDRs are generated at the end of a call, i.e. call termination, time threshold, volume threshold, and handoffs.
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RAM-disk: /records/udr/
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HDD: /hd-raid/data/records/udr/
File Formats: In this release, UDRs are supported in the Comma Separated Values (CSV) format.
Supported Products: GGSN, HA, PDSN