H3C Technologies H3C SecPath F5020 - Manual (Page 11)

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IRF functionality
Network topology
A security device IRF fabric can only use the daisy-chain topology. The device does not support the full
mesh or ring topology. For information about connecting IRF member devices, see " Connecting IRF
physical interfaces ."
Simplified topology
Devices in an IRF fabric appear as one node. For redundancy and load balancing, a downstream or
upstream device can connect to the IRF fabric through a multichassis link aggregation. Together with link
aggregation, IRF creates a loop-free Layer 2 network. The spanning tree feature is not needed among
devices in the IRF fabric or on the link aggregations. IRF also simplifies the Layer 3 network topology
because it reduces the number of routing peers.
The network topology does not change when a device is added to or removed from the IRF fabric.
For example, Device A and Device B are M9000 security gateways that form a two-chassis IRF fabric, as
shown in Figure 2 . The fabric has four MPUs (one active and three standbys), and two times the number
of interface cards that a single device provides. The IRF fabric manages the physical and software
resources of Device A and Device B in a centralized manner.