8320 / 8400 / ArubaOS-CX High Availability using MCLAG
The ArubaOS-CX operating system supports HA using an advanced implementation of MCLAG TODAY. It is at the same or higher level than similar technologies in the market.
The MCLAG solution is the same for 8400 and 8320 switches.
The MCLAG elements are:
- Control plane: Inter-Switch-Link and Keepalive
- Data plane L2: MCLAGs
- Data plane L3: Active gateway
What is MCLAG?
MCLAG is the technology that allows for the configuration of link-aggregation-groups (LAG) with member ports distributed across two chassis.
MCLAG is also the name of these distributed LAGs. These MCLAGs are layer 2 LAGs, and are the optimal solution when connecting layer 2 access devices like access switches and mobility controllers.
Why MCLAG?
MCLAG's main advantage is that it provides redundancy by providing dual homing to layer 2 access devices without the need for STP and at the same time keeps the management and control planes of the two aggregation devices independent, maximizing availability.
Control plane
The inter-switch-link is:
- a function that implements the coordination and synchronization of MCLAG information like LACP neighbors, MAC address tables, etc.
- configured on a link between the two chassis implemeting MCLAG - this link is not dedicated to this function, and it can and does carry other traffic
A separate IP-based keepalive mechanism completes the control plane by providing an integrity check in the case of an ISL failure.
Data plane:
MCLAGs are layer 2 LAGs configured on both chassis that connect to a single access device like a switch or mobility controller. From this 3rd device's LACP point of view, all ports in the LAG belong to a single device.
The Active Gateway is a layer 3 function of MCLAG that provides an active-active gateway for the clients connected to the access device(s).
What is VSX?
MCLAG as described above is available today.
VSX is the next generation of MCLAG, that will simplify the deployment, streamline the configuration, ensure configuration consistency across the two chassis, and take advantage of the unique database-centric OS architecture to provide deeper visibility into MCLAG's management, control and forwarding planes.