EVC Attributes

Some of the global EVC attributes are:

• EVC ID—An unique identifier that identifies the EVC
• EVC Type—E-LINE, E-LAN, or E-TREE
• List of associated EFPs that belong to an EVC

EFP Attributes

The key attributes of an EFP are:

• Encapsulation string—Defines the classification criteria for an incoming packet.
• Forwarding operations—Defines the forwarding operation to be applied on frames that belong to this EFP.
• Ingress rewrite operation—Defines the rewrites to be performed on the frames that belong to this EFP before proceeding with the forwarding operations.

Note	CPT supports only the Ingress rewrite operation and all the rewrite operations are symmetric in nature.

For a list of supported encapsulation and ingress rewrite operations on point–to–point (P2P) EVC and point–to–multipoint (P2MP) EVC, see Supported Encapsulation and Rewrite Operations.

Configuration Constraint

The encapsulation and rewrite operations are not allowed if the bridge domain is configured on the EFP. Remove the existing bridge domain from the EFP and then change the encapsulation and rewrite operations.

Types of Bridge Domains

The bridge domain can be configured to operate in point–to–pointand point–to–multipoint modes. The default configuration mode of the bridge domain is point–to–multipoint.

The types of bridge domains supported are:

Ethernet Private Line

An Ethernet Private Line (EPL) is a point–to–point EVC. EPL is an EVC that supports communication between two UNIs. In EPL, only one EVC can exist on a port and the port can have only one EFP. See Figure 1.

Figure 1. Ethernet Private Line

Ethernet Virtual Private Line

An Ethernet Virtual Private Line (EVPL) is a point–to–point EVC. EVPL is an EVC that supports communication between two UNIs. In EVPL, multiple EVCs can exist on a port and the port can have multiple EFPs. Each EFP is associated with a different bridge domain. See Figure 2.

Figure 2. Ethernet Virtual Private Line

Ethernet Private LAN

An Ethernet Private LAN (EPLAN) is a multipoint–to–multipoint EVC. EPLAN is an EVC that supports communication between two or more UNIs. In EPLAN, only one EVC can exist on a port and the port can have only one EFP. See Figure 3.

Figure 3. Ethernet Private LAN

Ethernet Virtual Private LAN

An Ethernet Virtual Private LAN (EVPLAN) is a multipoint–to–multipoint EVC. EVPLAN is an EVC that supports communication between two or more UNIs. In EVPLAN, multiple EVCs can exist on a port and the port can have multiple EFPs. Each EFP is associated with a different bridge domain. See Figure 4.

Figure 4. Ethernet Virtual Private LAN

Rooted Multipoint EVC

A rooted Multipoint EVC is a multipoint–to–multipoint EVC. In this EVC, the split horizon is configured on the access side EFPs. Figure 5 shows a rooted multipoint EVC with a split horizon configured between the two UNIs.

Figure 5. Rooted Multipoint EVC

CTC handles E-TREE services as a special case of EPLAN or EVPLAN.

Split Horizon

The rooted multipoint EVC supports split horizon. A split horizon is a subset of the members of a bridge domain.

The split horizon can be enabled for the service instances that are members of the multipoint bridge domain. This disables traffic among all the members of the bridge domain where split horizon is configured.

Note	CPT does not support split horizon groups.

Figure 6 shows an example of a multipoint bridge domain with four EFPs. The split horizon is configured on the three EFPs (EFP2, EFP3, and EFP4). The traffic is disabled among these three EFPs. Therefore, these three EFPs can only pass traffic to EFP1 and receive traffic from EFP1.

If the split horizon is configured on a Link Aggregation Group (LAG), the configurations apply to the entire LAG and not to the individual member ports.

Figure 6. Bridge Domain with Four EFPs

The following example configures a split horizon through Cisco IOS commands.

Router> enable
Router# configure terminal
Router(config)# interface TenGigabitEthernet 4/1
Router(config-if)# service instance 101 ethernet
Router(config-if-srv)# encapsulation  dot1q 100
Router(config-if-srv)# rewrite ingress tag push dot1q 20 symmetric
Router(config-if-srv)# bridge-domain 12 split-horizon 
Router(config-if-srv)# exit

Perform these steps to configure an EVC service instance under the point–to–multipoint bridge domain. To configure an EVC service instance under the point–to–point bridge domain, perform the DLP-J216 Configure a Bridge Domain Using Cisco IOS Commands procedure first and then perform this procedure.

This procedure allows you to perform the following:

• Create new end point EFPs for the EVC
• View the configurations of the EFPs
• Specify the QoS policies to apply on individual EFPs
• Specify the IGMP Snooping settings for the bridge domain
• Specify the MAC learning settings for the bridge domain
• Specify the multicast settings for the bridge domain

EVC with LAG

EFPs can be configured on a channel group. The traffic, carried by the EFPs, is load balanced across the member links. Ingress traffic for a single EVC can arrive on any member of the bundle. All egress traffic for an EFP uses only one of the member links. The load balancing is achieved by distributing EFPs between the member links. The EFPs on a channel group are grouped and each group is associated with a member link. In the default load balancing mechanism, there is no control over how the EFPs are distributed together, and sometimes the EFP distribution is not ideal. The manual load balancing mechanism can be alternatively used to control the EFP grouping.

When you configure a physical port as part of a channel group, you cannot configure EVCs under that physical port.

The number of LAGs supported is 128 with 8 member links for each LAG.

LACP protocol is supported on the LAG.

EVC with REP

EVC supports up to 32 segments. You can configure REP over EVC using the cross–connect or using the bridge domain at the service instance level. REP is not supported on service instances configured with encapsulation untagged or default type.

REP is not supported for Ethernet Private Line and Ethernet Virtual Private Line services.

EVC with MPLS

MPLS pseudowire circuits can be configured over the service instance infrastructure using xconnect commands to bind the EFPs.

All the encapsulation and rewrite operations are supported for MPLS pseudowire EFPs except the following:

• Symmetric rewrites do not support push 2 tag operations.
• Symmetric 1–to–2 and 2–to–1 translate operations are not supported.

EVC with Layer 2 Protocol Tunneling

CPT supports Layer 2 protocol tunneling only at the interface level. Configurations applied at the interface level are applicable to all the EFPs configured on that interface.

The following port actions are supported in this release:

• Forward—Forwards the unmodified ingress BPDUs on the data path.
• Drop—Drops the ingress BPDUs on the interface.
• Peer—Punts BPDUs to the local instance of the protocol.

Note	The pass option, tunnel option, and Layer 2 protocol tunneling at the EFP are not supported in this release.

The following protocols are supported for each port action:

The following table lists the default port action for each protocol:

See DLP-J212 Configure Layer 2 Protocol Tunneling Using Cisco IOS Commands and DLP-J213 Configure Layer 2 Protocol Tunneling Using CTC to configure Layer 2 protocol tunneling.

EVC with MAC Learning and MAC Address Limiting

MAC learning is supported and enabled (by default) only for point–to–multipoint bridge domains. MAC learning can be enabled or disabled for point–to–multipoint bridge domains.

The MAC address limiting for bridge domains provides the capability to control the MAC address learning behavior at the bridge domain level. You can configure an upper limit on the number of MAC addresses that reside in a bridge domain. The remaining MAC addresses are flooded because they are not learned.

The MAC address limiting commands are configured under the bridge domain.

The default MAC address limit on a bridge domain is 1024. The maximum MAC address limit on a bridge domain is 128000.

EVC with QoS

See EVCS QoS Support.

EVC with High Availability

All the EFP configurations are synchronized between the active and standby fabric cards.

EVC with MVR

Multicast VLAN Registration (MVR) is supported only for point–to–multipoint services. Twenty bridge domains can be configured for MVR. The multicast traffic flows from MVR source EFP to multiple MVR receiver EFPs.

EVC with IGMP Snooping

Internet Group Management Protocol Snooping (IGMP snooping) is supported only for point–to–multipoint services. IGMP snooping can be enabled only at the bridge domain level.