Multi-Chassis Trunking (MCT) is trunking that initiates at a single MCT-unaware server or switch and terminates at two MCT-aware switches. MCT allows the links to the two MCT-aware switches to appear to a downstream device as if they are coming from a single device on a single Link Aggregation (LAG) trunk interface or physical port.
Note
The SLX-OS device does not support Layer 2 protocols over MCT. Spanning Tree Protocol (STP) is disabled by default and must not be enabled with MCT. You must provide a loop-free topology.In a data center network environment, LAG trunks provide link level redundancy and increased capacity. However, they do not provide switch-level redundancy. If the switch connected to the LAG trunk fails, the entire trunk loses network connectivity.
With MCT, member links of the LAG trunk are connected to two MCT-aware devices. A configuration between the devices enable data flow and control messages between them to establish a logical Inter-Chassis Link (ICL). In this model, if one MCT device fails, a data path remains through the other device.
SLX-OS Layer 2 MCT cluster control protocol (CCP) synchronizes MAC, ARP, IGMP, and cluster management data between the MCT peers, for node resiliency and faster convergence.
On the SLX devices, the data plane is established using a VxLAN tunnel between MCT peers.
SLX-OS MCT provides Layer 3 protocol support for ARP, IPv4 and IPv6 BGP, OSPF, PIM, IGMP, ND6, and IS-IS through a VLAN or bridge domain VE interface. IPv4 or IPv6 Virtual Routing Redundancy Protocol (VRRP) and VRRP Extended (VRRP-E). is also supported.
SLX-OS MCT is only supported in the Default or Apptelemetry Hardware TCAM Profile.