Configuring SGCP

Operation

Configure SGCP on the Entire Switch

Display SGCP

Configure CES Circuits for SGCP

Display SGCP Endpoints

Display SGCP Connections

Configure SGCP Request Handling

Configure Call-Agent Address

SGCP Shutdown

Configuring SGCP

SGCP controls Voice over IP gateways by an external call control element (called a call-agent). This has been adapted to allow SGCP to control ATM switch circuit emulation service (CES) circuits (called endpoints in SGCP). The resulting system (call-agents and gateways) allows for the call-agent to engage in common channel signalling (CCS) over a 64-Kbps CES circuit, governing the interconnection of bearer channels on the CES interface. In this system the ATM switch acts as a Voice over ATM gateway.

Note For detailed information on how to configure your CES circuits, refer to the section "Configuring CES/T1 and E1 Interfaces" in the chapter, "Configuring Port Adapter Interfaces."

Figure 18-1 illustrates how 64-Kbps CCS channels on the CES T1 and E1 ports are backhauled or carried to the VSC 2700 units.

Figure 18-1: Common Channeling Signalling over a CES Circuit

A single trunk circuit sigA (on ATM switch A's CES port) carries or backhauls the CCS control call setup for the port. Trunk circuit sigB also controls a similar port on ATM switch B. SigA is backhauled over the ATM network to ATM switch C by a CES soft PVC to a circuit on another CES card port directly attached to a call-agent (VSC 2700 (1)). Similarly, sigB is backhauled to a CES circuit on ATM switch D.

Both call-agents are configured to handle backhauled signalling circuits to the CES trunk circuits. When a call-setup request is received on sigA by VSC 2700 (1), the VSC 2700 (1) cooperates with VSC 2700 (2) to establish the connection.

To dynamically connect the CES circuits located on ATM switches A and B, the call-agents use SGCP to allocate the CES circuits on each switch and then establishes a soft PVC between the switches. The resulting connection is callAB. Call-agents use SGCP to cause the ATM switches to set up and delete end-to-end connections between circuits.

Operation

The network operator can globally enable or disable SGCP operation for the switch. By default, SGCP is disabled. When SGCP is enabled, the ATM switch begins listening on the well-known User Datagram Protocol (UDP) port for SGCP packets. The endpoint ID in an SGCP packet identifies the CES circuit. The CES circuit endpoint can be used by SGCP if the following conditions exist:

The parent CES interface is enabled, and the LineState is NoAlarm. (Determined via the show ces interface command.)
The CES circuit is allocated a single time slot.
The CES circuit is enabled (not shut).
The CES circuit is not configured as an active soft PVC.
The CES circuit is not configured as part of a hard PVC.

The following sections describe SGCP configuration tasks:

Configure SGCP on the Entire Switch
Configure CES Circuits for SGCP
Configure SGCP Request Handling
Configure Call-Agent Address

Configure SGCP on the Entire Switch

To enable SGCP operations for the entire switch, use the global configuration command, as shown in the following table:

Command Purpose

sgcp

SGCP operations are enabled or disabled for the entire switch.

Command	Purpose
sgcp	SGCP operations are enabled or disabled for the entire switch.

Example

The following example shows how to enable SGCP for the entire switch:

Switch(config)# sgcp

Display SGCP

To display SGCP configuration, operational state, and a summary of connection activity, use the following privileged EXEC command:

Command Purpose

show sgcp

Displays the global SGCP configuration.

Command	Purpose
show sgcp	Displays the global SGCP configuration.

Example

The following example displays the SGCP configuration:

Switch# show sgcp
SGCP Admin State ACTIVE, Oper State ACTIVE
SGCP call-agent:none  , SGCP graceful-shutdown enabled? FALSE
SGCP request timeout 2000, SGCP request retries 6
74 CES endpoint connections created
74 CES endpoints in active connections

Configure CES Circuits for SGCP

Any single time slot (64 Kbps) allocated to a circuit on a CES T1 or E1 interface can be configured for SGCP with these restrictions:

CES is not the active source end of a soft PVC.
CES is not part of a hard PVC.

Note Configuration on the call-agent can restrict the range of circuits designated for signalling on a CES circuit interface.

When you configure a CES circuit for SGCP, signalling should be given the proper time slot. For T1 CES circuits, a time slot can be given a number from 1 to 24; for E1 CES, a number from 1 to 31.

Although no keyword identifies a CES circuit as allocatable by SGCP, there is normally a simple configuration rule to ensure that signalling allocates the proper time slot:

: circuit x is allocated time slot x, 1<=x<=24 (or 31 for E1).

Note The endpoint specifier used by SGCP refers to the CES circuit ID (not the time slot). If a time slot is not allocated to a circuit, that time slot cannot be used by SGCP (or CES, either).

To configure SGCP operation on a CES circuit interface, perform the following steps, beginning in global configuration mode:

Step Command Purpose

1
interface cbr card/subcard/port

Selects the physical interface to be configured.

2
ces aal1 service structured

Configures the CES interface AAL1 service type.

3
ces circuit circuit_id timeslot timeslot_#

Allocates time slot number to circuit identifier.

Step	Command	Purpose
1	interface cbr card/subcard/port	Selects the physical interface to be configured.
2	ces aal1 service structured	Configures the CES interface AAL1 service type.
3	ces circuit circuit_id timeslot timeslot_#	Allocates time slot number to circuit identifier.

Example

The following example shows how to configure the CES port for structured CES services with all time slots available for SGCP. CES circuit 16 is configured for common channel signalling and specified as a soft PVC to a circuit on the CES PAM connected to the call-agent:

Switch(config)# interface CBR1/1/2
Switch(config-if)# ces aal1 service structured
Switch(config-if)# ces circuit 1 timeslot 1
Switch(config-if)# ces circuit 2 timeslot 2
Switch(config-if)# ces circuit 3 timeslot 3
Switch(config-if)# ces circuit 4 timeslot 4
Switch(config-if)# ces circuit 5 timeslot 5
Switch(config-if)# ces circuit 6 timeslot 6
Switch(config-if)# ces circuit 7 timeslot 7
Switch(config-if)# ces circuit 8 timeslot 8
Switch(config-if)# ces circuit 9 timeslot 9
Switch(config-if)# ces circuit 10 timeslot 10
Switch(config-if)# ces circuit 11 timeslot 11
Switch(config-if)# ces circuit 12 timeslot 12
Switch(config-if)# ces circuit 13 timeslot 13
Switch(config-if)# ces circuit 14 timeslot 14
Switch(config-if)# ces circuit 15 timeslot 15
Switch(config-if)# ces circuit 16 timeslot 16
Switch(config-if)# ces pvc 16 dest-address
47.0091.8100.0000.0060.3e64.fd01.4000.0c80.1038.10 vpi 0 vci 2064
Switch(config-if)# ces circuit 17 timeslot 17
Switch(config-if)# ces circuit 18 timeslot 18
Switch(config-if)# ces circuit 19 timeslot 19
Switch(config-if)# ces circuit 20 timeslot 20
Switch(config-if)# ces circuit 21 timeslot 21
Switch(config-if)# ces circuit 22 timeslot 22
Switch(config-if)# ces circuit 23 timeslot 23
Switch(config-if)# ces circuit 24 timeslot 24
Switch(config-if)# end

Display SGCP Endpoints

SGCP endpoints are all the CES circuits that might be eligible for SGCP connections. To display SGCP endpoints, use the following EXEC command:

Command Purpose

show sgcp endpoint [interface cbr card/subcard/port [circuit_id]]

Displays the SGCP endpoints.

Command	Purpose
show sgcp endpoint [interface cbr card/subcard/port [circuit_id]]	Displays the SGCP endpoints.

Note SGCP cannot allocate a CES circuit to a connection if it is already part of a hard or soft PVC.

Example

The following example displays the possible SGCP endpoints on CES interface cbr1/1/0:

Switch> show sgcp endpoint interface cbr1/1/0
Endpt         Timeslots Conn State            Call ID
CBR1.1.0/1         1    no connection
CBR1.1.0/2         1    no connection
CBR1.1.0/3         1    no connection
CBR1.1.0/4         1    no connection
CBR1.1.0/5         1    no connection
CBR1.1.0/6         1    no connection
CBR1.1.0/7         1    no connection
CBR1.1.0/8         1    no connection
CBR1.1.0/9         1    no connection
CBR1.1.0/10        1    no connection
CBR1.1.0/11        1    active
CBR1.1.0/12        1    no connection
CBR1.1.0/14        1    active             1234abc
CBR1.1.0/15        1    active             2234abc
CBR1.1.0/16        1    active             3234abc
CBR1.1.0/17        1    active             4234abc
CBR1.1.0/18        1    active             5234abc
CBR1.1.0/19        1    active             6234abc
CBR1.1.0/20        1    active             7234abc
CBR1.1.0/21        1    active             8234abc
CBR1.1.0/22        1    active             9234abc
CBR1.1.0/23        1    active             a234abc
CBR1.1.0/24        1    active             b234abc

Display SGCP Connections

To display SGCP connections (either globally or per single interface), use the following EXEC command:

Command Purpose

show sgcp connection [interface cbr card/subcard/port]

Displays the SGCP connections.

Command	Purpose
show sgcp connection [interface cbr card/subcard/port]	Displays the SGCP connections.

Example

The following example displays all SGCP connections created on the ATM switch:

Switch> show sgcp connection
Conn Endpt          Soft VC State        Call Id
CBR0.0.0/1         Dest- active VC       d234ab
CBR0.0.0/2         Dest- active VC       12345bc
CBR0.0.0/3         Dest- active VC       1284ab
CBR0.0.0/4         Dest- active VC       9234abc

Configure SGCP Request Handling

When the ATM switch initiates an SGCP request (for example, to disconnect the circuit), default request timer and request retry values are in operation. To change the default value of SGCP requests, use the global configuration commands, as shown in the following table:

Command Purpose

sgcp request timeout timeval

Configures the SGCP request timeout value.

sgcp request retries retryval

Configures the SGCP request retry value.

Command	Purpose
sgcp request timeout timeval	Configures the SGCP request timeout value.
sgcp request retries retryval	Configures the SGCP request retry value.

Examples

The following example shows how to change the request timeout to 2000 milliseconds:

Switch(config)# sgcp request timeout 2000

The following example shows how to change the request retry value to 5:

Switch(config)# sgcp request retries 5

Configure Call-Agent Address

By default:

The ATM switch sends a response to an SGCP request in a UDP packet with the destination address the same as the source address of the request UDP packet.
To send a DeleteConnection request for a connection that exists, the ATM switch specifies the destination address of the UDP packet as the source UDP address in the CreateConnection request.

To alter this behavior, and send responses and requests to a specific IP address and UDP port, use the following global configuration command:

Command Purpose

sgcp call-agent host_IPaddr UDP_port

Configures the call-agent IP address and UDP port.

Command	Purpose
sgcp call-agent host_IPaddr UDP_port	Configures the call-agent IP address and UDP port.

Note If the IP address is specified without the UDP port number, the well-known SGCP port 2427 is used.

Example

The following example shows how to set the call-agent with IP address 133.20.5.122 and UDP port 12000:

Switch(config)# sgcp call-agent 133.20.5.122 12000

SGCP Shutdown

When SGCP is disabled with the no sgcp command, active SGCP connections are terminated; however DeleteConnection requests are not sent to the call-agent for these active connections. To notify call-agent and perform a graceful SGCP shutdown, use the following global configuration command:

Command Purpose

sgcp graceful-shutdown

Shuts down SGCP and notifies call-agent.

Command	Purpose
sgcp graceful-shutdown	Shuts down SGCP and notifies call-agent.

Example

The following example shows how to perform a graceful shutdown:

Switch(config)# sgcp graceful-shutdown

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