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Introduction
Circuit Cross Connect (CCC) connection service provides the capability to transport bidirectional frame relay traffic over an IP/MPLS backbone. This traffic is transported over a pair of pre-configured uni-directional transmit and receive MPLS Tunnels. The PVC traffic arrives at an Avici router as RFC 1490 frames. A frame relay PVC is the entry and exit point for the CCC connection service. The frame relay PVC encapsulates the frame for transport over the IP/MPLS backbone before sending the packet on to the tunnel ingress. At the tunnel egress frame relay PVC the frame is reconstructed based on frame-relay UNI rules and transmitted over a predefined PVC.
The following steps are required at both ends of the CCC service:
- Configure the frame relay interface
- Create a frame relay PVC
- Establish the connection
Frame relay runs on a POS interface that initially defaults to PPP encapsulation. Creation of a frame relay PVC requires that the interface encapsulation first be changed to frame relay. The interface encapsulation command provides for the changing of encapsulation from PPP to frame relay.
A frame relay PVC is created at each end of the CCC service. These frame relay PVCs connect two geographically displaced frame relay devices and carry bi-directional traffic from one end of the CCC service to the other end. Frame relay PVCs are configured by entering PVC configuration mode, specifying the interface and DLCI, and setting the PVC encapsulation to frame relay circuit cross connect (FRL-CCC).
Once the interface encapsulation and the PVC is configured for the interface at both ends of the CCC service, a connection between the service points is configured. There are three connection types: PVC tunnel, Tunnel stitch, and PVC-to-PVC.
The three CCC connection types are as follows:
PVC tunnel - Provides a Circuit Cross Connect based on a To-tunnel and From-tunnel association. Each tunnel is configured with the no traffic option (this prevents PPP traffic from flowing over the tunnel). Backup tunnels may be associated with both the To and From tunnels. Figure 8-1 "PVC-Tunnel Connection, displays a generic PVC-tunnel connection service. At each end of the service, RFC 1490 compatible devices forward frame relay traffic to the CCC service. The entry point for the traffic is a frame relay PVC. A connection is configured at both ends associating To and From tunnels. The To tunnel at the entry end of the connection is configured as the From tunnel at the exit end.
Figure 8-1. PVC-Tunnel Connection
Tunnel stitch - Provides for the connection of two tunnels that have ingress and egress points on a midpoint switch of the intended connection service. The tunnel stitch connection associates an egress From-tunnel with an ingress To-tunnel. Traffic arriving on the From-tunnel at the midpoint switch is forwarded out on the To-tunnel to the other end of the connection. From the point of view of the connection service, a tunnel stitch creates a single logical tunnel. The tunnel stitch is configured before creating the PVC-tunnel connection. Figure 8-2 "Tunnel-Stitch Connection displays a generic midpoint tunnel stitch connection. The From tunnel with the ingress at frame relay PVC A is stitched to the To tunnel with the egress at frame relay PVC B. The From tunnel with the ingress at frame relay PVC B is stitched to the To tunnel with the egress at frame relay PVC A.
Figure 8-2. Tunnel-Stitch Connection
PVC stitch - Provides a PVC to PVC connection between the entry and exit interfaces of a single router. In this case the connection functions as a PVC switch for this router. This connection is formed by associating the interface and DLCI for the router entry and exit interfaces. This connection type is also referred to as a PVC stitch.
Figure 8-3. PVC-To-PVC Connection
Each frame relay PVC supports a maximum-frame size of 10K that is configurable on a per port basis using the mtu command. Frame fragmentation and reassembly do not take place during CCC connection service transit.
Each frame relay interface is assigned a unique Weighted Fair Queue Group for QoS configuration purposes. An EXP value can be configured per frame relay PVC. Each PVC maps the QoS behavior for the to-tunnel egress point to a configured EXP value. See the "Quality of Service Configuration" discussion in this document for Weighted Fair Queue and EXP details.
For this release CCC connection service does not support the CIR, Bc and Be traffic parameters.
Configuring a Frame Relay Interface
In order to create a frame relay PVC on an interface, the interface must be configured as a frame relay interface. To configure a frame relay interface, the interface encapsulation must be changed from the default of PPP to frame-relay as follows:
- Enter interface configuration mode using the interface pos bay/slot/port command for the interface desired.
- Shutdown the interface using the shutdown command.
- Change the encapsulation for the interface from the default of PPP to frame relay using the encapsulation frame-relay command.
- Perform a no shutdown on the interface.
Example: In the following example, the encapsulation for interface 1/4/1 is changed to frame-relay:
router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
router(config)#interface pos 1/4/1
router(config-if)#shutdown
router(config-if)#encapsulation frame-relay
router(config-if)no shutdown
router(config-if)end
router#
Creating a Frame Relay PVC
Once the frame relay interface is configured, create a frame relay PVC at each end of the CCC service. There are two parts to configuring a PVC: associating a DLCI with the service point interface and setting PVC encapsulation to FRL-CCC.
Use the interface frl-pvc command, specifying the interface and DLCI association, to enter PVC configuration command mode. Once in PVC configuration command mode, the PVC is initially created with a default encapsulation of NULL.
For a PVC to be included in a connection, its encapsulation must be set to FRL-CCC. Use the encapsulation frl-ccc command in PVC configuration command mode to set the encapsulation to frame relay CCC encapsulation for this PVC. Use the exp command to optionally change the EXP value for this PVC.
Use the no interface frl-pvc command to delete a PVC from the specified frame relay interface. PVCs can not be deleted if already part of a connection. Remove the connection prior to deleting a PVC.
Example: In the following example a PVC is created on interface 1/4/1 by:
- Configuring an interface with encapsulation frame-relay.
- Creating a PVC by entering PVC configuration mode and associating DLCI 21 with the PVC.
- Setting PVC encapsulation to frl-ccc and the EXP to 3.
- Specifying a PVC description.
- Enabling the PVC with the no shutdown command.
router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
router(config)#interface pos 1/4/1
router(config-if)#encapsulation frame-relay
router(config-if)#no shutdown
router(config-if)#exit
router(config)#interface frl-pvc 1/4/1.21
router(config-pvc)#encapsulation frl-ccc
router(config-pvc)#exp 3
router(config-pvc)#description Bos-Doc DLCI 21 to 23 CCC connection
router(config-pvc)#no shutdown
router(config-if)#end
router#
Configuring a Connection
There are three connection types used to configure a CCC service: PVC tunnel, tunnel stitch, and PVC stitch:
- The PVC tunnel connection type specifies the to-tunnel with one optional backup tunnel and the from-tunnel with up to three optional backup tunnels to connect each end of the CCC service.
- The tunnel stitch joins two different tunnels at a midpoint node creating a single logical tunnel. If an ingress of one tunnel and an egress of another tunnel are established, the two tunnels can be stitched to form a single logical tunnel.
- The PVC stitch provides a PVC switch function between the entry and exit interfaces of a single router.
All tunnels in a CCC service must be configured with the no traffic option to prevent undesired PPP traffic from being forwarded over the tunnel.
Configuring a PVC Tunnel
Frame relay traffic is transported over a pair of pre-configured uni-directional transmit and receive MPLS tunnels: a to-tunnel and from-tunnel at each frame relay PVC. At each frame relay PVC a To tunnel is configured specifying the no traffic option. The To tunnel configured at a given frame relay PVC is specified as the From tunnel of the frame relay PVC at the other end of the connection. One backup To tunnel can be optionally specified. Up to three backup From tunnels can be optionally specified.
Use the connection name pvc-tunnel command to enter connection configuration mode. In connection configuration mode specify the To tunnel and From tunnel, as well as any desired backup tunnels. Perform a no shutdown to enable the connection.
A PVC tunnel connection can be modified by:
- Performing a shutdown of the connection
- Deleting the tunnel and associated backups using the no version of the appropriate tunnel command (to-tunnel and from-tunnel)
- Entering the new tunnel for this connection using the appropriate tunnel command (to-tunnel or from-tunnel)
- Performing a no shutdown to enable the connection.
Figure 8-4 "PVC-Tunnel Example, displays a PVC tunnel example configuration within a complete CCC service.
On the Boston side of the service an RFC 1490 compatible device forwards frame relay traffic to the frame relay PVC 1/1/1.21. A connection named BosCCC is configured at this end of the service. The ingress to the Bos21 tunnel is established at this end of the CCC service along with a single backup tunnel named BkBos21. The Bos21 tunnel is specified as the To tunnel for the BosCCC connection along with the BkBos21 backup. Frame relay traffic received from the Chicago side of the service is over the Chi23 tunnel. The Chi23 tunnel is specified as the From tunnel for the BosCCC connection. The BkChi23a and BkChi23b backup tunnels are configured as the From tunnel backups for the BosCCC connection.
On the Chicago side of the service an RFC 1490 compatible device forwards frame relay traffic to the frame relay PVC 1/1/5.23. A connection named ChiCCC is configured at this end of the service. The ingress to the Chi23 tunnel is established at this end of the CCC service along with a single backup tunnel named BkChi23. The Chi23 tunnel is specified as the To tunnel for the ChiCCC connection along with the BkChi23 backup. Frame relay traffic received from the Boston side of the service is over the Bos21 tunnel. The Bos21 tunnel is specified as the From tunnel for the ChiCCC connection. The BkBos21a and BkBos21b backup tunnels are configured as the From tunnel backups for the ChiCCC connection.
Figure 8-4. PVC-Tunnel Example
Example: In the following example a complete CCC service connection is configured starting with the 1/1/1.21 frame relay PVC configured with:
- PVC-tunnel connection named BosCCC.
- A to-tunnel named Bos21 with a backup named BkBos21.
- A from-tunnel named Chi23 with two backups named BkChi23a and BkChi23b.
router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
router(config)#interface pos 1/1/1
router(config-if)#encapsulation frame-relay
router(config-if)#no shutdown
router(config-if)#exit
router(config)#interface frl-pvc 1/1/1.21
router(config-pvc)#encapsulation frl-ccc
router(config-pvc)#description Bos-Doc DLCI 21 to 23 CCC connection
router(config-pvc)#no shutdown
router(config-pvc)#exit
router(config)#connection BosCCC pvc-tunnel frl-pvc 1/1/1.21
router(config-cxn)#to-tunnel Bos21 backup BkBos21
router(config-cxn)#from-tunnel Chi23 backup BkChi23a BkChi23b
router(config-cxn)#no shutdown
router(config-cxn)#end
router#
The other end of the CCC service connection is configured at the frame relay PVC 1/1/5.23 with:
- PVC-tunnel connection named ChiCCC.
- A to-tunnel named Chi23 with a backup named BkChi23.
- A from-tunnel named Bos21 with two backups named BkBos21a and BkBos21b.
router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
router(config)#interface pos 1/1/5
router(config-if)#encapsulation frame-relay
router(config-if)#no shutdown
router(config-if)#exit
router(config)#interface frl-pvc 1/1/5.23
router(config-pvc)#encapsulation frl-ccc
router(config-pvc)#description Chi-Doc DLCI 23 to 21 CCC connection
router(config-pvc)#no shutdown
router(config-pvc)#exit
router(config)#connection ChiCCC pvc-tunnel frl-pvc 1/1/5.23
router(config-cxn)#to-tunnel Chi23 backup BkChi23
router(config-cxn)#from-tunnel Bos21 backup BkBos21a BkBos21b
router(config-cxn)#no shutdown
router(config-cxn)#end
router#
Configuring a Tunnel Stitch
Two uni-directional tunnels can be stitched together to form a static span across an Avici router. The tunnel with the egress at this midpoint is specified as the from-tunnel. The tunnel with the ingress at this midpoint is specified as the to-tunnel. Traffic arriving on the from-tunnel is forwarded out the to-tunnel.
Use the connection name tunnel-stitch command to enter connection configuration mode. In connection configuration mode specify the from-tunnel on which traffic will arrive at the stitch and the to-tunnel on which traffic is forwarded to the service point at the other end of the CCC connection. Perform a no shutdown to enable the stitch connection.
A tunnel stitch connection can be modified by:
- Performing a shutdown of the connection
- Deleting the tunnel and associated backups using the no version of to-tunnel and from-tunnel associated with the tunnel stitch.
- Entering the new set of to and from tunnels for this stitch connection using the appropriate tunnel command (to-tunnel or from-tunnel).
- Performing a no shutdown to enable the new connection.
Figure 8-5 "CCC Tunnel-Stitch Example displays a tunnel stitch connection in the context of a CCC service that stitches a Boston/Chicago service at an Albany midpoint. Two tunnel stitches are configured.
The first tunnel stitch is named BosStitch. This connection stitches the Bos21 tunnel to the BosAlb21 tunnel at the Albany node. This stitch creates a single logical tunnel for traffic forwarded through Albany from Boston to Chicago. The BosStitch is configured by associating the Bos21 From tunnel with the BosAlb21 To tunnel along with the appropriate backups.
The second tunnel stitch is named ChiStitch. This connection stitches the Chi23 tunnel to the ChiAlb23 tunnel at the Albany node. This stitch creates a single logical tunnel for traffic forwarded through Albany from Chicago to Boston. The ChiStitch is configured by associating the Chi23 From tunnel with the ChiAlb23 To tunnel along with the appropriate backups.
Once the stitch is configured, the PVC tunnel connection between Boston and Chicago can be configured.
Figure 8-5. CCC Tunnel-Stitch Example
Example: In the following example a tunnel stitch is performed at an Albany CCC service connection midpoint for the Boston to Chicago direction using the connection name tunnel-stitch command to stitch the Bos21 tunnel to the BosAlb21 tunnel along with associated backup tunnels:
router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
router(config)#connection BosStitch tunnel-stitch
router(config-cxn)#to-tunnel BosAlb21 backup BkBosAlb21
router(config-cxn)#from-tunnel Bos21 backup BkBos21a BkBos21b router(config-cxn)#no shutdown
router(config-cxn)#end
router#
The example continues with the Chicago to Boston direction using the connection name tunnel-stitch command to stitch the Chi23 tunnel to the ChiAlb23 tunnel along with associated backup tunnels:
router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
router(config)#connection ChiStitch tunnel-stitch
router(config-cxn)#to-tunnel ChiAlb23 backup BkChiAlb23
router(config-cxn)#from-tunnel Chi23 backup BkChi23a BkChi23b router(config-cxn)#no shutdown
router(config-cxn)#end
router#
Configuring a PVC-TO-PVC Connection
The PVC-stitch connection provides a PVC switch function for a single router by associating an entry interface and DLCI with an exit interface and DLCI. For this association to take place: setup two PVCs, one on the entry and exit interfaces, and assign frl-pvc encapsulation to them.
Once the interface encapsulation and the PVC configuration are complete, configure the PVC-to-PVC connection using the connection name pvc-stitch command in configuration mode to enter connection configuration mode. Perform a no shutdown in connection configuration mode to enable the PVC-to-PVC connection.
Figure 8-6. PVC-to-PVC Connection Example
Example: In the following example a PVC-stitch connection is created on the router entry interface 1/1/1 and associated with the exit interface 1/2/5. First the interface encapsulation and PVC configuration are performed on interface 1/1/1 by:
- Enabling the interface with encapsulation frame-relay.
- Creating a PVC on the interface and associating DLCI 21 with the PVC.
- Setting PVC encapsulation to frl-ccc.
- Specifying a PVC description.
- Enabling the PVC with the no shutdown command.
router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
router(config)#interface pos 1/1/1
router(config-if)#encapsulation frame-relay
router(config-if)#no shutdown
router(config-if)#exit
router(config)#interface frl-pvc 1/1/1.21
router(config-pvc)#encapsulation frl-ccc
router(config-pvc)#description Avici-Doc DLCI 21 to 23 PVCtoPVC connection
router(config-pvc)#no shutdown
router(config-pvc)#exit
router(config)#
Next the frame relay interface encapsulation and PVC configuration are performed on the exit interface 1/1/5 by:
- Enabling the interface with encapsulation frame-relay.
- Entering PVC configuration mode while associating DLCI 23 with the interface.
- Setting PVC encapsulation to frl-ccc.
- Specifying a PVC description.
- Enabling the PVC with the no shutdown command.
router(config)#interface pos 1/2/5
router(config-if)#encapsulation frame-relay
router(config-if)#no shutdown
router(config-if)#exit
router(config)#interface frl-pvc 1/2/5.23
router(config-pvc)#encapsulation frl-ccc
router(config-pvc)#description Avici-Doc DLCI 23 to 21 PVCtoPVC connection
router(config-pvc)#no shutdown
router(config-pvc)#exit
router(config)#
Lastly the following PVC-to-PVC connection command is entered to complete the PVC switch:
router(config)#connection foo pvc-stitch frl-pvc 1/1/1.21 frl-pvc 1/2/5.23
router(config-cxn)#no shutdown
router(config-cxn)#end
router#
Configuring LMI on a Frame Relay PVC
IPriori has been enhanced to support the Local Management Interface (LMI) protocol on a frame relay PVC. IPriori supports the LMI ANSI standard which reserves DLCI 0.
Enabling LMI on a frame relay interface configures a frame relay PVC using DLCI 0 on the interface to provide status updates across the frame relay link. If the interface is part of a CCC connection service, active/inactive TLVs are included in the PATH message sent over the MPLS cloud.
The Avici router acts as a DCE to the DTE at the other end of the frame relay link. Message exchanges provide for updates on link integrity (keepalive), full status for all frame relay PVCs on the Avici router, and asynchronous PVC updates between the DTE and DCE. If a CCC connection service exists, an active/inactive TLV is included in the PATH message exchange to an Avici router on the other side of an MPLS cloud. To configure LMI on a frame relay PVC:
- Enable frame relay encapsulation on the frame relay interface using the encapsulation frame-relay command
- Enable ANSI LMI on the frame relay interface using the frame-relay lmi-type ansi command
See Figure 8-7 "LMI Status Update Configuration" for a presentation of the LMI functionality and configuration.
Figure 8-7. LMI Status Update Configuration
PROCEDURE: Use the following procedure to enable LMI on an Avici router frame relay PVC:
Step 1 Enter interface configuration mode for the frame relay port using the interface pos b/s/p command and shutdown the interface using the shutdown command.
Step 2 Within interface configuration mode, enable frame relay encapsulation using the encapsulation frame-relay command.
Step 3 Within interface configuration mode, enable LMI for this interface using the frame-relay lmi-type ansi command.
Step 4 Enter a no shutdown command to enable the interface followed by the end command to exit configuration modes.
router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
router(config)#interface pos 1/4/1
router(config-if)#shutdown
router(config-if)#encapsulation frame-relay
router(config-if)#frame-relay lmi-type ansi
router(config-if)#no shutdown
router(config-if)#end
router#
Use the interface pos b/s/p command to enter interface mode in order to enable LMI on the interface.
Use the frame-relay lmi-type ansi command to enable LMI on the interface.
Configuring Router Management Capability on a Frame Relay PVC
IPriori provides for the configuration of a routing interface used to manage the Avici router through a frame relay PVC. A new frame relay PVC type (frl-routed) configured on a PVC configured for DLCI 1 only, provides for the configuration of router interface management of an Avici router through a frame relay PVC. The source IP address for the router management interface is configured using the ip address command in PVC configuration mode. The destination address is configured using the peer default ip address command.
See Figure 8-8 "Router Management Interface on a Frame Relay PVC" for a presentation of router management interface configuration on a frame relay PVC.
Figure 8-8.Router Management Interface on a Frame Relay PVC
PROCEDURE: Use the following procedure to enable router management on an Avici router frame relay PVC:
Step 1 Enter interface configuration mode for the frame relay port using the interface pos b/s/p command and shutdown the interface using the shutdown command.
Step 2 Within interface configuration mode, enable frame relay encapsulation using the encapsulation frame-relay command.
Step 3 Perform a no shutdown on the interface and exit using the exit command.
Step 4 Configure this interface for frame relay PVC using the interface frl-pvc b/s/p.1 command specifying DLCI 1.
Step 5 Within frame relay PVC configuration mode, enable frame relay routed encapsulation using the encapsulation frl-routed command.
Step 6 Use the ip address a.b.c.d/n command to configure the source IP address for router management.
Step 7 Use the peer default ip address command to enable the other side of the link as the destination address.
Step 8 Enter a no shutdown command to enable the PVC at this end. Enter an end command to leave configuration mode.
router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
router(config)#interface pos 1/4/1
router(config-if)#shutdown
router(config-if)#encapsulation frame-relay
router(config-if)#no shutdown
router(config-if)#exit
router(config)#interface frl-pvc 1/4/1.1
router(config-pvc)#shutdown
router(config-pvc)#encapsulation frl-routed
router(config-pvc)#ip address 1.1.1.1/24
router(config-pvc)#peer default ip address
router(config-pvc)#no shutdown
router(config-if)#end
router#
Use the interface frl-pvc b/s/p.1 command to enter frame relay PVC configuration mode for a router management PVC.
Use the ip address command within PVC configuration mode to specify the source IP address for this router management link.
Use the peer default ip address to configure the destination address as the other side of the router management link.
Displaying Frame Relay PVC LMI and Router Interface Management Statistics
Use the show interface pos command to display LMI information within an interface context.
Use the show interface pos frame-relay lmi command to display LMI specific operational status and counters information.
Use the show interface frame-relay lmi command to display all LMI instances
Use the show connections command to display local and far-end PVC state.
Use the clear counters all command to clear all LMI related counters on the router or the clear counters pos b/s/p command to clear counters by port.
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Copyright © 2004
Avici Systems Inc.
Avici® and TSR®
is a registered trademark of Avici Systems Inc.
IPriori™, Composite Links™, SSR™, QSR, and NSR® are
trademarks of Avici Systems Inc.
Source
File Name: CCCconfig.fm
HTML File Name: CCCconfig.html
Last Updated: 12/19/04 at 16:17:56