Topology Collection; Role Election - H3C S5820 Configuration Manual

IRF topology
An IRF virtual device typically adopts daisy chain connection or ring connection, as shown in
1-5.
A daisy chain connection is mainly used in a network where member devices are distributedly
located.
A ring connection is more reliable than the daisy chain connection. In a daisy chained IRF virtual
device, the failure of one link can cause the IRF virtual device to partition into two independent IRF
virtual devices; where the failure of a link in a ring connection result in a daisy chain connection, not
affecting IRF services.
Figure 1-5 IRF connections
Master
IRF-Port1
Slave
IRF-Port1
Slave
Daisy chain
connection

Topology Collection

Each member exchanges hello packets with the directly connected neighbors to collect topology of the
IRF virtual device. The hello packets carry topology information, including IRF port connection states,
member IDs, priorities, and bridge MAC addresses.
Each member records its known topology information locally. At the initiation of the collection, the
members record their own topology information. When an IRF port of a member becomes up, the
member sends its known topology information from this port periodically. Upon receiving the topology
information, the directly connected neighbor updates the local topology information.
The collection process lasts for a period of time. When all members have obtained the complete
topology information (known as topology convergence), the IRF virtual device enters the next stage:

role election.

Role Election
The process of defining the role (master or slave) of members is role election.
Role election is held when the topology changes, such as, forming an IRF virtual device, adding a new
member, leaving or failure of the master, or IRF virtual device partition. The master is elected based on
IRF
virtual
device
IRF-Port2
IRF-Port2
Master
IRF-Port1
IRF virtual
device
IRF-Port2 IRF-Port1
IRF-Port1
Slave
Ring connection
1-6
IRF-Port2
IRF-Port2
Slave
Figure