MC-LCR extends the functionality offered by SC-LCR to include protection against 7705 SAR node failure. With MC-LCR, the working adapter card of an LCR group is configured on one 7705 SAR node while the protection adapter card of the same LCR group is configured on a different 7705 SAR node. The working and protection nodes are connected by an IP link (directly or indirectly) that establishes a multi-chassis protocol (MCP) link between the nodes.
MC-LCR is supported for TDM CES (Cpipes). MC-LCR with TDM access is supported on DS1, E1, and DS0 (64 kb/s) channels.
MC-LCR supports TDM SAP-to-SAP connections when both LCR SAPs are configured using the same adapter card on each node.
MC-LCR also supports TDM SAP-to-spoke SDP connections over an MPLS network. In this configuration, the far-end connection may or may not be configured for LCR.
The working and protection adapter cards must be the same type and must have compatible configurations, such as the same speed, framing, and port type. The adapter cards in an LCR group on both the working and protection nodes must also have the same group ID. The LCR groups can have different descriptions. In order for MC-LCR to function correctly, pseudowire redundancy must be configured on both the working and protection adapter cards. For information about pseudowire redundancy, refer to the 7705 SAR Services Guide, ‟Pseudowire Redundancy”. MC-LCR with pseudowire redundancy also supports Inter-Chassis Backup (ICB); see MC-LCR and Inter-Chassis Backup for more information.
The working and protection nodes can be different platforms, such as a 7705 SAR-8 Shelf V2 and a 7705 SAR-18. However, to prevent possible switchover performance issues, avoid mixing different adapter card types in the same MC-LCR group. The 7705 SAR does not enforce configuration consistency between the working adapter card and the protection adapter card. Additionally, no service or network-specific configuration data is signaled or synchronized between the two nodes.
An MCP link can be established using the IP link between the two nodes by matching LCR group IDs. The signaling path verifies that one node is configured as the working adapter card and the other is configured as the protection adapter card. In case of a mismatch, an incompatible neighbor trap is generated. The protection node uses member adapter card status and the settings configured in the LCR Tools Commands to select the working adapter card. Changes in working adapter card status are sent across the MC-LCR signaling link from the working node to keep the protection node synchronized. External requests such as lockout and force switch are allowed only on the node with the protection adapter card.