Table Of Contents

Configuring iSCSI Support

iSCSI Overview

Configuring an iSCSI Target Interface Profile on the CSG2

Associating an iSCSI Target Interface Profile with the CSG2

Configuring the iSCSI Packet Drain Settings

Verifying the iSCSI Session

Configuring iSCSI Support

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Under normal conditions, the CSG2 sends call detail records (CDRs) to the Billing Mediation Agent (BMA). If for any reason those BMAs cannot be reached, CDRs are sent to the Cisco Persistent Storage Device (PSD) for safekeeping until contact is reestablished with the BMAs. When contact is reestablished, the CSG2 retrieves the CDRs from the PSD and forwards them to the BMAs. For more information, see the "Configuring PSD Support" section on page 7-1.

Instead of using the PSD as backup storage, the CSG2 can use the Storage Area Network (SAN) connected to the Internet Small Computer Systems Interface (iSCSI) to store CDRs until the BMAs can be reached. This chapter describes that function.

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Note The CSG2 supports only one type of backup device, either a PSD or an iSCSI device. The PSD and iSCSI features can coexist, but only one can be enabled at a time.

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The CSG2 provides the following features for the SAN connected to the iSCSI:

•iSCSI Overview

•Configuring an iSCSI Target Interface Profile on the CSG2

•Associating an iSCSI Target Interface Profile with the CSG2

•Configuring the iSCSI Packet Drain Settings

•Verifying the iSCSI Session

iSCSI Overview

The iSCSI transport protocol operates over TCP/IP, enabling mobile operators and service providers to use their SAN connected to an iSCSI to save CDRs.

SAN technology, which enables customers to build scalable storage solutions, is comprised of the following primary elements:

•SCSI—An interface standard which enables multiple devices to be installed on a system, attached to cable to form a chain of devices. Each device is assigned a unique ID, which is expressed as a number, that identifies that device on the bus. SCSI IDs can be broken into Logical Unit Numbers (LUNs), enabling a number of devices to share a single SCSI ID. Devices from which I/O requests originate are called initiators, and devices from which responses originate are called targets.

•SAN—Technology that involves moving network storage to a separate network of its own. Disk, tape, and optical storage can then be attached to the storage network that is based on a fabric of switches and hubs that connects storage devices to a heterogeneous set of servers.

A SAN system provides block-level access to data residing on shared storage arrays through dedicated storage networks.

Under normal conditions, the SAN connected to the iSCSI provides standby capabilities when necessary—for example, during network outages. The SAN stores the payload from the packet in a queue, and is unaware of the content or format of that data, so that the data can be retrieved exactly as it was sent.

Once the CSG2 determines that the regular data server is again reachable (in this case, the BMA), it retrieves the stored data from the SAN. The data is returned to the CSG2 in the same order and form as it was deposited. The CSG2 is responsible for maintaining order, if necessary, or of mixing retrieved data with incoming "live" records. Once the CSG2 acknowledges to the SAN that it has successfully sent the data to the data server (the BMA), the SAN deletes that data. The SAN stores the data until it receives this acknowledgement.

•iSCSI—Transport protocol that maps SCSI requests and responses over TCP and provides block-level data transfer between the SCSI initiator (such as the CSG2), and the target (the storage device on the SAN). The initiator sends I/O requests and the target sends I/O responses.

A SAN topology is distinguished by the following features:

•Storage is not directly connected to network clients.

•Storage is not directly connected to servers.

•Storage devices are interconnected.

•Multiple servers can share multiple storage devices.

When configuring iSCSI CDR backup and storage on the CSG2, keep the following considerations in mind:

•Currently, iSCSI targets cannot be dynamically discovered.

•The number of TCP connections per iSCSI session is limited to one.

•The iSCSI target device should be preformatted. Each LUN must have only one FAT32 partition.

•Maximum of size of a LUN must not be more than 2TB, which is the maximum disk size supported by a FAT32 file system.

Configuring an iSCSI Target Interface Profile on the CSG2

In the SCSI environment, the CSG2 functions as an iSCSI initiator. To enable the CGS2 to use the SAN for CDR backup storage, you must first configure an iSCSI target interface profile on the CSG2 that includes the name and IP address of the target, and the TCP port on which to "listen" for iSCSI traffic.

To configure the iSCSI target interface profile on the CSG2, complete the following tasks, beginning in global configuration mode:

	Command	Purpose
Step 1	Router(config)# ip iscsi target-profile target-profile-name	Creates an iSCSI profile for an iSCSI target on the CSG2, and enters iSCSI configuration mode Note You can configure one and only one iSCSI profile on a given CSG2.
Step 2	Router(config-iscsi)# name target-name	Specifies the name of an iSCSI target in the target profile on the CSG2
Step 3	Router(config-iscsi)# ip ip-address	Specifies the IP address of an iSCSI target in the target interface profile on the CSG2.
Step 4	Router(config-iscsi)# port port-number	Specifies the number of the port on which to listen for iSCSI traffic in the iSCSI target interface profile on the CSG2.

Associating an iSCSI Target Interface Profile with the CSG2

After you have configured the iSCSI target interface profile on the CSG2, you must configure the CSG2 to use the iSCSI for CDR storage when no BMA is available. To do so, you must associate the iSCSI target interface profile with the CSG2. This enables the CSG2 to read from and write to the remote SAN, using the iSCSI.

To associate an iSCSI target interface profile with the CSG2, enter the following command in global configuration mode:

Command	Purpose
csg2(config)# ip csg iscsi profile target-profile-name	Specifies the iSCSI target interface profile to be used as backup storage for the CSG2. Note You can associate one and only one iSCSI target interface profile at a time with a given CSG2. The profile name specified must be the same as the one configured using the ip iscsi target-profile command.

Configuring the iSCSI Packet Drain Settings

When the BMA becomes active, the CSG2 begins draining CDRs from the SAN.

By default, the CSG2 limits the rate at which GTP' messages are read from the SAN to 167 packets/second. However, you can change that rate. For example, you can specify an interval of 2 seconds to yield a rate of 250 packets/second (500 packets/2 seconds).

To configure a delay before the CSG2 begins draining packets, enter the following command in global configuration mode:

Command	Purpose
csg2(config)# ip csg iscsi drain delay number-of-seconds	(Optional) Defines the delay interval, in seconds, before draining packets from the iSCSI when the BMA becomes active.

You can also change the rate at which GTP' messages are read from the SAN by changing the number of packets to be drained per interval. For example, specifying that 600 packets are to be drained per interval yields a rate of 200 packets/second (600 packets/3 seconds).

To configure the number of packets to be drained from the iSCSI, enter the following command in global configuration mode:

Command	Purpose
csg2(config)# ip csg iscsi drain packet number-of-packets	(Optional) Defines the number of packets to be drained from the iSCSI per drain delay interval when the BMA becomes active.

Verifying the iSCSI Session

To verify that the iSCSI session is up, use the following command in privileged EXEC mode:

Command	Purpose
Router# show ip iscsi session	Displays the status of iSCSI session.