Application of MC-LAGs

This topic describes the application of MC-LAGs. MC-LAGs work with Ethernet ring protection switching (ERPS) to provide network-wide protection for Ethernet services on the metropolitan area networks (MANs).

Figure 1 shows the typical application of MC-LAGs with ERPS.

LAG 1 and LAG 2 (blue lines in the figure) form the MC-LAG protection domain to provide dual-homing protection for upstream Ethernet services. LAG 1 is the primary link and LAG 2 is the standby link.
The Ethernet ring formed by in the figure is the ERPS protection domain that provides link protection for Ethernet services on the ring.

Figure 1 Application of MC-LAGs Working with ERPS

The following are requirements for application of MC-LAGs working with ERPS:

The south ports for the MC-LAG must be the same as the east and west ports (see and in Figure 1) of the ERPS ring. This configuration ensures independence of the ERPS protection domain and the MC-LAG protection domain while providing protection networkwide.
It is recommended to configure ERPS protection for the MCSP by routing the MCSP to the east and west ports of the ERPS ring.
Do not create two MCSPs on an ERPS ring with the same Protocol Path ID.

Service Switching in the Application of MC-LAG Working with ERPS

When the MC-LAG works with ERPS, the MC-LAG service switching mode is specific to the Ethernet service type.

The EVPLAN service
Figure 2 describes the EPLAN(IEEE 802.1q Bridge or IEEE 802.1ad Bridge) service switching mode during MC-LAG switchover.
Figure 2 EPLAN(IEEE 802.1q Bridge or IEEE 802.1ad Bridge) Service Switching Mode
The switching process is as follows:
1. The MC-LAG blocks ports in LAG 1.
2. The MC-LAG activates the standby link LAG 2.
3. The virtual bridge (VB) deletes the MAC addresses of the ports in the MC-LAG from the dynamic MAC address table and relearns these MAC addresses. Then the VB forwards the EVPLAN services to LAG 2 based on the newly learned MAC addresses.
The EVPLAN service
Figure 3 describes the EVPL service switching mode during MC-LAG switchover.
Figure 3 EVPL Service Switching Mode
- When the MC-LAG is functioning properly, Ethernet services are forwarded over the link between the port in the active LAG and the south port of the MC-LAG ().
- When the MC-LAG performs switchover, it automatically creates a link between the two south ports ( and ) to let EVPL services pass through to the south port connected to the standby LAG. Then the standby LAG forwards the EVPL services to the router.

NOTE:

For more information about MC-LAG application, see the OptiX OSN 8800 Product Documentation.