Multi-Chassis LAG
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Point-to-Point (p2p) Redundant Connection Across Layer 2/3 VPN Network
Figure 6: P2P Redundant Connection Through a Layer 2 VPN Network
Figure 6 shows the connection between two multi-service access nodes (MSANs) across network
based on Layer 2/3 VPN pseudo-wires. The connection between MSAN and a pair of PE routers is
realized by MC-LAG. From MSAN perspective, redundant pair of PE routers acts as a single
partner in LACP negotiation. At any point in time, only one of the routers has an active link(s) in a
given LAG. The status of LAG links is reflected in status signaling of pseudo-wires set between all
participating PEs. The combination of active and stand-by states across LAG links as well and
pseudo-wires give only 1 unique path between pair of MSANs.
Aggregation
node
A
Aggregation
node
C
MSANMSAN
Aggregation
node
B
Aggregation
node
C
Inter-chassis
PW for VLL
Active
Active
Active
Active
Standby
Standby
Standby
Standby
Standby
TLDP
Standby Active
Active
Inter-chassis
PW for VLL
Aggregation
node
A
Aggregation
node
C
MSANMSAN
Aggregation
node
B
Aggregation
node
C
Inter-chassis
PW for VLL
Active
Standby
Standby
TLDP
Active
Inter-chassis
PW for VLL