The following section explains the configuration commands for enabling the feature on a Cisco router. The configuration tasks needed to enable the individual functionality in the feature are listed as follows:
Configuring Frame Relay switching and creating switched PVCs on both serial and ISDN interfaces
Configuring Frame Relay Traffic Shaping on outgoing switched PVC
Configuring Frame Relay policing on incoming switched PVC
Configuring Frame Relay congestion management

NOTE:IOS Software Release 12.2(1) is used on the routers in the Cisco test lab for the purpose of the discussion in this section.

Configuring Frame Relay Switching on Switched PVC for Serial and ISDN Interfaces
Before configuring , Frame Relay switching must be enabled globally on the router. To enable Frame Relay switching, use the frame-relay switching global configuration command as follows:
Router(config)#frame-relay switching
To create switched PVCs, use the following commands, beginning from the global configuration mode:
Step 1. Define the connections between Frame Relay PVCs using the connect connection-name interface dlci interface dlci global configuration command. Note that the global connect command assigns DLCI numbers to the respective switched interfaces on the router. The connect command works similarly to the frame-relay route command.
Step 2. (optional) To attach a Frame Relay map class defined with traffic shaping or policing parameters to a switched PVC, you are required to identify a PVC as switched. To identify a PVC as switched, use the frame-relay interface-dlci dlci [switched] interface configuration command.

Example 6-1 shows both configuration examples of configuring switched PVCs over a serial interface and over an ISDN B channel. In both cases in this example, switched DLCI 100 is connected to switched DLCI 200. DLCI 200 is explicitly identified as a switched PVC using the frame-relay interface-dlci dlci switched interface configuration command. This command enters the user into the frame-relay interface-dlci configuration mode where a Frame Relay map class that is set up with user-defined shaping or policing parameters can be directly associated with the switched PVC.

Example 6-1. Creating Switched PVC and Identifying a DLCI as a Switched PVC
frame-relay switching
!
interface serial 3/2
encapsulation frame-relay
frame-relay intf-type dce
clock rate 56000
!
interface serial 4/2
encapsulation frame-relay
frame-relay intf-type dce
clock rate 56000
frame-relay interface-dlci 200 switched
!
connect fast serial3/2 100 serial4/2 200

frame-relay switching
!
isdn switch-type basis-5ess
!
interface bri 1/0
dialer pool-member 1
!
interface dialer1
encapsulation frame-relay
dialer pool 1
dialer-group 1
dialer caller 4085253422
dialer string 4085253422
frame-relay intf-type dce
!
interface serial 3/2
encapsulation frame-relay
frame-relay intf-type dce
clock rate 56000
!
connect fast serial3/2 100 dialer1 200
!
dialer-list 1 protocol ip permit

NOTE:When configuring a router as a Frame Relay switch in a Frame Relay network, you are required to identify the connected interface on the switch router as a DCE device. This is accomplished using the frame-relay intf-type dce interface configuration command. Because the routers in the lab are connected directly back-to-back on serial cables, the clock rate command is required on the DCE side to supply clocking on the line to the other DTE interface.

Configuring Frame Relay Traffic Shaping on Outgoing Switched PVC
To configure Frame Relay Traffic Shaping on switched PVCs, Frame Relay Traffic Shaping must be enabled first at the egress interface. To enable Frame Relay Traffic Shaping, use the frame-relay traffic-shaping interface configuration command as follows:
Router(config-if)#frame-relay traffic-shaping

NOTE:When using Frame Relay Traffic Shaping together with Frame Relay switching, Frame Relay Traffic Shaping does not apply to “routed PVCs” created with the legacy frame-relay route command.

After Frame Relay Traffic Shaping is enabled under the main interface, a Frame Relay map class with user-defined traffic shaping parameters can be associated with each switched VC. To associate a Frame Relay map class directly with the switched PVCs, use the following commands, beginning from the interface configuration mode:
Step 1. In the interface configuration mode of the main interface, identify the DLCI of the PVC with the frame-relay interface dlci switched interface configuration command.
Step 2. Associate the created Frame Relay map class directly with the switched PVC using the class map-class-name configuration command.

It is optional to associate a Frame Relay map class with the switched PVC. If no map class is associated with the switched PVC, the default traffic shaping parameters are applied to the switched PVC. By default, the value of CIR is 56,000, Bc is 7000, and Be is 0. Creating a Frame Relay map class for Frame Relay policing follows the same rules of inheritance applied to terminated PVCs in Frame Relay Traffic Shaping.

If there are no traffic shaping parameters defined in a Frame Relay map class and policing is configured on the ingress side of the switched PVC, Frame Relay Traffic Shaping calculates the shaping values based on the configured policing values as follows:
Frame Relay Traffic Shaping CIR = Policing CIR + Policing EIR (equivalent to Bc/Tc + Be/Tc)
Traffic Shaping MinCIR = Policing CIR
Traffic Shaping Bc = Policing Bc + Policing Be
Traffic Shaping Be = 0

Example 6-2 demonstrates the traffic shaping map class inheritance for switched PVCs.

Example 6-2. Frame Relay Traffic Shaping on Switched PVC
frame-relay switching
!
interface serial4/2
encapsulation frame-relay
clock rate 56000
frame-relay intf-type dce
frame-relay traffic-shaping
frame-relay class fast_vc
frame-relay interface-dlci 100 switched
class slow_vc
!
interface serial2/1
encapsulation frame-relay
clock rate 56000
frame-relay intf-type dce
!
connect slow serial4/2 100 serial2/1 300
connect fast serial4/2 200 serial2/1 400
!
map-class frame-relay fast_vc
frame-relay cir 64000
frame-relay bc 8000
frame-relay be 0
!
map-class frame-relay slow_vc
frame-relay cir 32000
frame-relay bc 4000
frame-relay be 0

In Example 6-2, the Frame Relay map class slow_vc is explicitly applied to switched PVC 300/100. Hence, the traffic shaping parameters defined in the slow_vc map class are used for shaping the traffic on switched PVC 300/100 before its entry to the Frame Relay network. On the other hand, switched PVC 400/200 is not explicitly associated with any map class at the DLCI level. Hence, it implicitly inherits the shaping parameters from the Frame Relay map class fast_vc defined at the main interface level using the frame-relay class fast_vc interface configuration command.

Configuring Frame Relay Policing on Incoming Switched Interface
To enable Frame Relay policing on an ingress interface and configure traffic policing parameters, use the frame-relay policing interface configuration command as follows:
Router(config-if)#frame-relay policing

NOTE:It is possible to configure Frame Relay Traffic Shaping and Frame Relay policing on the same interface. When both are enabled on the same interface, Frame Relay Traffic Shaping acts on outgoing traffic, and Frame Relay policing polices incoming traffic.
It is necessary to set up the Frame Relay policing parameters in a Frame Relay map class to define the values for performing Frame Relay policing on the ingress switched PVC.

The Frame Relay policing parameters that can be defined in the map class are CIR, Bc, Be, and Tc.To set up the policing parameters for Frame Relay policing, perform the following configuration tasks, beginning in global configuration mode:
Step 1. In the global configuration mode, create a Frame Relay map class by specifying a map class name with the map-class frame-relay map-class-name interface configuration command. This enters the user into the map-class configuration mode.
Note that in Steps 2 through 4 that follow, the command supports a new in option so that the value is used exclusively for Frame Relay policing.
Step 2. In the map-class configuration mode, the values of CIR, Bc, Be, and Tc can be defined as follows:
Step 3. Specify the incoming CIR rate with the frame-relay cir in bps map-class configuration command.
Step 4. Specify the incoming Bc value with the frame-relay Bc in bps map-class configuration command.
Step 5. Specify the incoming Be value with the frame-relay Be in bps map-class configuration command.
Step 6. Specify the Tc period with the frame-relay tc milliseconds map-class configuration command. This command is optional. By default, the Tc value is calculated from the Bc/CIR. The Tc value is set up only when the CIR is zero.
Step 7. Identify the switched PVC with the frame-relay interface-dlci dlci switched interface configuration command. Associate the Frame Relay map class created with the policing parameters using the class map-class-name command.
NOTE:The new in and out keywords in the Frame Relay map class configuration commands for defining CIR, Bc, and Be values are meant to distinguish between traffic shaping and policing parameters when the same map class is used for both Frame Relay Traffic Shaping and Frame Relay policing. When defining the parameters for traffic shaping, use the out keyword. The in keyword should be used when defining policing parameters.

Example 6-3 is a configuration example of applying Frame Relay policing parameters to the switched PVC using a Frame Relay map class.

Example 6-3. Configuring Frame Relay Policing and Applying Policing Parameters in a Map Class
frame-relay switching
!
interface serial4/2
encapsulation frame-relay
clock rate 64000
frame-relay intf-type dce
frame-relay policing
frame-relay interface-dlci 100 switched
class traffic_police
!
interface serial2/1
encapsulation frame-relay
clock rate 64000
frame-relay intf-type dce
!
connect switching serial4/2 100 serial2/1 300

!
map-class frame-relay traffic_police
frame-relay cir in 64000
frame-relay bc in 8000
frame-relay be in 0

Configuring Frame Relay Congestion Management
As mentioned earlier in this chapter, it is possible to configure two levels of Frame Relay congestion management on a Cisco router. The first level applies Frame Relay congestion management directly on the traffic shaping queues of individual switched PVCs transmitting traffic in excess of the CIR. In this mode, only FIFO queues are supported.

The second level applies to the output interface queue, which acts on all of the switched PVCs that are created at the interface as a whole. The first level gives users more granular control by allowing congestion management to be applied directly to the selected switched PVCs.
To configure Frame Relay congestion management on the FIFO traffic-shaping queues of individual switched PVCs, first create a Frame Relay map class to define the threshold values, beginning in the global configuration mode, as follows:
Step 1. In the global configuration mode, create a Frame Relay map class with the map-class frame-relay map-class-name interface configuration command. This enters the user into the map-class configuration mode.
Step 2. Configure the threshold at which received DE-marked packets will be discarded from the traffic shaping queues of the switched PVC using the frame-relay congestion threshold de percentage map-class configuration command. The percentage specified is pegged to the traffic shaping queue depth. When the queue is at or above the DE threshold, packets with the DE bit set will be discarded instead of queued.
Step 3. Configure the threshold at which Explicit Congestion Notification (ECN) bits (BECN and FECN) will be set on packets in the traffic shaping queues of the switched PVC using the frame-relay congestion threshold ecn percentage map-class configuration command. The percentage specified is pegged to the traffic shaping queue depth. When the queue is at or above the ECN threshold, all packets received will be marked with FECN or BECN bit according to their direction of travel.
Step 4. Configure the maximum size of the FIFO traffic-shaping queue on the switched PVC with the frame-relay holdq queue-size map-class configuration command. Valid queue size is from 1 to 512.
Step 5. Associate the Frame Relay map class with the switched PVC. First, identify the switched PVC at the interface configuration mode with the frame-relay interface-dlci dlci switched interface configuration command. Then associate the Frame Relay map class with the switched PVC using the class map-class-name command.

Example 6-4 is a configuration example of applying Frame Relay congestion management on individual switched PVCs. The traffic-shaping hold queue on DLCI 200 is configured at 100, and the congestion threshold for DE is set at 50. This implies that when the traffic shaping hold queue is at or has exceeded 50 percent (50/100) capacity, Frame Relay packets received with the DE bit set are discarded instead of queued.

Example 6-4. Configuring Frame Relay Congestion Management Applied to Individual Switched PVC
frame-relay switching
!
interface Serial3/0
no ip address
encapsulation frame-relay
clockrate 64000
frame-relay traffic-shaping
frame-relay interface-dlci 200 switched
class congestion
frame-relay lmi-type ansi
frame-relay intf-type dce
!
interface Serial4/0
no ip address
encapsulation frame-relay
clockrate 64000
frame-relay intf-type dce
!
map-class frame-relay congestion
frame-relay holdq 100
frame-relay congestion threshold de 50
!
connect switch Serial4/0 100 Serial3/0 200

NOTE:To apply Frame Relay congestion management directly on the traffic shaping queues of individual switched PVCs on an interface, Frame Relay Traffic Shaping must be enabled on the interface.

To enable Frame Relay congestion management on all switched PVCs on an interface, use the frame-relay congestion-management interface configuration command, as follows:
Router(config-if)#frame-relay congestion-management
Router(config-fr-congest)#

This enters the user into the Frame Relay congestion management subconfiguration mode. In the Frame Relay congestion management subconfiguration mode, configure the congestion management threshold as follows:
Step 1. In the Frame Relay congestion management subconfiguration mode, configure the threshold at which received DE-marked packets will be discarded from switched PVCs on the output interface using the threshold de percentage configuration command. The percentage specified is pegged to the queue depth of the interface output hold queue. When the queue is at or has exceeded the DE threshold, all packets with the DE bit set crossing the interface will be discarded instead of queued.
Step 2. In the Frame Relay congestion management configuration mode, configure the threshold at which ECN bits will be set on packets in switched PVCs on the output interface using the threshold ecn { bc | be } percentage configuration command. The percentage specified is pegged to the queue depth of the interface output hold queue. When the queue is at or has exceeded the ECN threshold, the BECN or FECN bit is set in the packets crossing the interface corresponding to the direction of traffic.
Step 3. (optional) Set the size of the interface output queue using the hold-queue queue-size out interface configuration command. Valid queue size is from 0 to 4096.
Refer to Example 6-5 for configuring congestion management at the interface level. The output queue size can be adjusted from the default of 40 to a value between 0 and 4096 using the hold-queue queue-size {in | out} command. In this example, the threshold for ECN is set at 50 percent for Bc traffic. This implies that when the output hold queue has exceeded 50 percent capacity, the interface will set the BECN and FECN bits in packets transmitted on the interface to notify a congestion condition. When the output queue size is over 75 packets, the DE threshold configured with the threshold de command is reached, and all DE marked packets subsequently received are dropped from the interface output queue.

Example 6-5. Configuring Congestion Management on the Interface
frame-relay switching
!
interface Serial3/0
no ip address
encapsulation frame-relay
no fair-queue
clockrate 64000
frame-relay traffic-shaping
frame-relay lmi-type ansi
frame-relay intf-type dce
frame-relay congestion-management
threshold ecn bc 50
threshold de 75
hold-queue 100 out
!
interface Serial4/0
no ip address
encapsulation frame-relay
clockrate 64000
frame-relay intf-type dce
!
connect switch Serial4/0 100 Serial3/0 200

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