Technical Documentation

Supported Platforms
M10i Routers, M120 Routers, M320 Routers, M7i Routers
MX240 Routers, MX480 Routers, MX960 Routers
T640 Routers

Related Topics
Configuring the Method and Reason in ServiceChange Commands for Contexts

Controlling ServiceChange Commands Sent from the Virtual BGF to the Gateway Controller

For seamless interoperability between the BGF and gateway controller devices, you can control the method and reason that the virtual BGF includes in ServiceChange commands that it sends to the gateway controller. You can also prevent the system from being overloaded with messages for certain state changes by specifying that the virtual BGF not send a request or notification when those changes occur.

You can specify the method and reason that the virtual BGF includes in ServiceChange commands when the state of one of the following changes:

Control associations
Virtual interfaces
Contexts

This topic covers:

Control Association States

A control association is a relationship where the gateway controller is controlling the virtual BGF. Each virtual BGF has only one control association at any time.

Table 1 describes the control association states.

Table 1: Control Association States

Control Association State	Description
Disconnected	The control association is in the Disconnected state. No gateway controller is controlling the virtual BGF, and incoming H.248 messages are ignored. The control association remains disconnected as long as the virtual BGF is Out-of-Service. Depending on what caused the virtual BGF to become Out-of-Service, the virtual BGF either drops H.248 commands or answers them with a port-unreachable ICMP error.
Connecting	The control association is in Connecting state between the time the virtual BGF sends a registration request to the gateway controller and the time the gateway controller accepts, rejects, or aborts the request. The virtual BGF rejects incoming H.248 commands while the control association is in the Connecting state with error # 505: “Transaction Request Received before a ServiceChange Reply has been received”.
Draining	The control association enters the Draining state when an administrator instructs the virtual BGF to gracefully transition from In-Service to Out-of-Service. The gateway controller transitions to Out-of-Service when the controlling gateway controller subtracts all of the virtual BGF’s H.248 terminations. The virtual BGF accepts only Subtract and AuditValue commands from the controlling gateway controller. It rejects all other commands with error # 502: “Not Ready”.

Control Association State

Description

Disconnected

The control association is in the Disconnected state. No gateway controller is controlling the virtual BGF, and incoming H.248 messages are ignored. The control association remains disconnected as long as the virtual BGF is Out-of-Service.

Depending on what caused the virtual BGF to become Out-of-Service, the virtual BGF either drops H.248 commands or answers them with a port-unreachable ICMP error.

Connecting

The control association is in Connecting state between the time the virtual BGF sends a registration request to the gateway controller and the time the gateway controller accepts, rejects, or aborts the request.

The virtual BGF rejects incoming H.248 commands while the control association is in the Connecting state with error # 505: “Transaction Request Received before a ServiceChange Reply has been received”.

Draining

The control association enters the Draining state when an administrator instructs the virtual BGF to gracefully transition from In-Service to Out-of-Service. The gateway controller transitions to Out-of-Service when the controlling gateway controller subtracts all of the virtual BGF’s H.248 terminations.

The virtual BGF accepts only Subtract and AuditValue commands from the controlling gateway controller. It rejects all other commands with error # 502: “Not Ready”.

When the state of a control association changes, the virtual BGF can send the following types of ServiceChange commands to the gateway controller:

Registration requests—The virtual BGF sends a Registration Request ServiceChange command to request that a gateway controller become its controlling gateway controller. The virtual BGF sends these requests when a control association enters the Connecting state.
Unregistration messages—The virtual BGF sends an Unregistration ServiceChange command to its controlling gateway controller when it transitions to the Out-of-Service (Disconnected) service state because of an administration operation or a failure. The failure can be the result of a services PIC, Flexible PIC Concentrator (FPC), or MS-DPC failure, or because the PIC or DPC was powered off or removed.
Notification messages—The virtual BGF sends a notification ServiceChange command to its controlling gateway controller when the control association transitions between the Connected and Draining states and vice versa.

Method and Reason Options for Control Association State Changes

You can control the ServiceStateMethod and ServiceStateReason that the virtual BGF includes in ServiceChange commands for control associations.

You can use the CLI to specify the method and reason that the virtual BGF includes in ServiceChange commands for control associations. Table 2 shows the method and reason options available for each reported state and the events that led to the report.

Table 2: Options for Method and Reason in ServiceChange Commands for Control Associations

Reported Association State	Event Leading to Report	Options	Embedded H.248 Reason	Explanation
Disconnect	Controller failure	FL/909	Gateway controller impending failure	Virtual BGF is reregistering with a new gateway controller following a disconnection of the virtual BGF and gateway controller.
	Controller failure	RS/902	Warm boot	Virtual BGF is reregistering with a new gateway controller following a disconnection of the virtual BGF and gateway controller.
	Reconnect	DC/900	Service restored	Virtual BGF is registering with the last controlling gateway controller following a disconnection of the virtual BGF and gateway controller.
	Reconnect	RS/902	Warm boot	Virtual BGF is transitioning to In-Service, and the previously installed state is retained.
Down	Administrative	FO/905	Termination taken out of service	Virtual BGF is transitioning to Out-of-Service because of an administrative operation.
		FO/908	VPG impending failure	Virtual BGF root termination transitioned to Out-of-Service and is unable to process request.
		none		No message is sent for this event.
	Failure	FO/904	Termination malfunctioning	Virtual BGF is transitioning to Out-of-Service because of a failure.
		FO/908	VPG impending failure	Virtual BGF root termination transitioned to Out-of-Service because of a failure.
		none		No message is sent for this event.
	Graceful	GR/905	Termination taken out of service	The control association entered the Draining state because of an administrative operation.
	Graceful	none		No message is sent for this event.
Up	Cancel graceful	RS/908	Cancel graceful	The control association transitioned from the Draining state to the Forwarding state.
	Cancel graceful	none		No message is sent for this event.
	Cold failover	FL/920	Cold failover	Virtual BGF is registering following a graceful Routing Engine switchover. The previously installed state is reset.
	Cold failover	RS/901	Cold boot	Virtual BGF is transitioning to In-Service. The previously installed state is not retained.
	Warm failover	FL/919	Gateway controller impending failure	Virtual BGF is registering with a new gateway controller following a disconnection of the virtual BGF and gateway controller.
	Warm failover	RS/902	Warm boot	Virtual BGF is transitioning to In-Service, and the previously installed state is retained.

Virtual Interface States

Table 3 describes the virtual interface states.

Table 3: Virtual Interface States

Virtual Interface Operational State	Description
Blocked	A virtual interface is in the Blocked state when the interface is Out-of-Service. While a virtual interface is in the Blocked state, all VPGs do not add new terminations using the interface. Likewise, the virtual BGF rejects H.248 commands other than Subtract and AuditValue commands on existing terminations on the interface. The error that the virtual BGF returns for commands that it rejects depends on the reason that caused the virtual interface to be Out-of-Service: Error #502: "Not ready"—If the virtual interface is Out-of-Service because of an administrative operation. Error #529: "Internal hardware failure in PG"—If the virtual interface is Out-of-Service because of a failure.
Forwarding	A virtual interface is in the Forwarding state when it is functioning normally. All gates are using the interface process data flows according to the H.248 properties installed on them.
Draining	A virtual interface enters the Draining state when an administrator instructs the virtual interface to gracefully transition from In-Service to Out-of-Service. The virtual interface automatically transitions to Out-of-Service when it is no longer used by any termination in any of the virtual BGFs. A virtual interface that is in the Draining state is In-Service and existing gates process data flows normally. However, as in the Blocked state, the virtual BGFs do not add new terminations using that virtual interface or to perform any command other than Subtract and AuditValue on existing terminations on the interface. If the virtual BGF receives other commands, it replies with error #502: "Not ready".

Virtual Interface Operational State

Description

Blocked

A virtual interface is in the Blocked state when the interface is Out-of-Service.

While a virtual interface is in the Blocked state, all VPGs do not add new terminations using the interface. Likewise, the virtual BGF rejects H.248 commands other than Subtract and AuditValue commands on existing terminations on the interface. The error that the virtual BGF returns for commands that it rejects depends on the reason that caused the virtual interface to be Out-of-Service:

Error #502: "Not ready"—If the virtual interface is Out-of-Service because of an administrative operation.
Error #529: "Internal hardware failure in PG"—If the virtual interface is Out-of-Service because of a failure.

Forwarding

A virtual interface is in the Forwarding state when it is functioning normally. All gates are using the interface process data flows according to the H.248 properties installed on them.

Draining

A virtual interface enters the Draining state when an administrator instructs the virtual interface to gracefully transition from In-Service to Out-of-Service. The virtual interface automatically transitions to Out-of-Service when it is no longer used by any termination in any of the virtual BGFs.

A virtual interface that is in the Draining state is In-Service and existing gates process data flows normally. However, as in the Blocked state, the virtual BGFs do not add new terminations using that virtual interface or to perform any command other than Subtract and AuditValue on existing terminations on the interface. If the virtual BGF receives other commands, it replies with error #502: "Not ready".

When the state of a virtual interface changes, the virtual BGF can send the following types of ServiceChange commands to the gateway controller:

Service-Restoration—The virtual BGF sends Service-Restoration ServiceChange commands when a virtual interface transitions to the In-Service service state; that is, it transitions from the Blocked state to the Forwarding operational state.
Service-Interruption—The virtual BGF sends Service-Interruption ServiceChange commands when a virtual interface transitions to the Out-of-Service, or Blocked, service state.
Notification messages—The virtual BGF sends Notification ServiceChange commands when a virtual interface transitions between the Forwarding and Draining states and vice versa.

Method and Reason Options for Virtual Interface State Changes

You can control the ServiceStateMethod and ServiceStateReason that the virtual BGF includes in ServiceChange commands for virtual interface state changes.

You can use the CLI to specify the method and reason that the virtual BGF includes in ServiceChange commands for virtual interfaces. Table 4 explains the method and reason options available for each reported state and the events that led to the report.

Table 4: Options for Method and Reason in ServiceChange Commands for Virtual Interfaces

Reported State	Event Leading to Report	Options	Embedded H.248 Reason	Explanation
Virtual interface down	Administrative	FO/905	Termination taken out of service	Virtual interface is transitioning to Out-of-Service because of an administrative operation.
		FO/906	Loss of lower-layer connectivity	Virtual interface is transitioning to Out-of-Service because of a loss of layer 2 connectivity caused by the logical or physical interface being administratively disabled.
		none		No message is sent for this event.
	Graceful	GR/905	Termination taken out of service	Virtual interface has entered the Draining state.
	Graceful	none		No message is sent for this event.
Virtual interface up	Cancel graceful	RS/918	Cancel graceful	Virtual interface has returned to the Forwarding state.
	Cancel graceful	none		No message is sent for this event.
	warm	RS/900	Service restored	Virtual interface has become In-Service and is in the Forwarding state.
	warm	none		No message is sent for this event.

Context States

The virtual BGF sends context Service-Interruption messages when the gates of a specific context no longer provide their configured service. When such a message is issued, both terminations included in the context become Out-of-Service.

You can use the CLI to specify the method and reason that the virtual BGF includes in Service-Interruption ServiceChange commands that it sends to the gateway controller when a state loss occurs. Table 5 describes the method and reason options available.

Table 5: Options for Method and Reason in ServiceChange Commands for Specific Contexts

Reported State	Event Leading to Report	Options	Embedded H.248 Reason	Explanation
State loss	Mismatch between pgcpd process and Service PIC or MS-DPC states	FO/910	State loss because of a media failure	A mismatch between the pgcpd process and the services PIC or MS-DPC states was detected on one or more of the context’s gates.
		FO/915	State loss	A mismatch between the pgcpd process and the services PIC or MS-DPC states was detected on one or more of the context’s gates.
		none		No message is sent for this event.