H3C Technologies H3C S7500E Series Switches - Manual (Page 13)

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Figure 1-5 Physical connections of IRF virtual device
The orange line in the figure represents the IRF link, which is different from a common Ethernet link. An
IRF link can be composed of either one physical cable or multiple physical links.
Topology Collection
Each member exchanges hello packets with the directly connected neighbors to collect topology of the
IRF virtual device. The hello packets carry the topology information, including IRF port connection
states, member IDs, priorities, and bridge MAC addresses.
Each member is managed by its active SRPU, which records its known topology information locally. At
the startup of a member device, the active SRPU of the member device records topology information of
the member device. When an IRF port of the member device becomes up, the active SRPU of the
member device performs the following operations:
1) Periodically sends its known topology information from this port.
2) Upon receiving the topology information from the directly connected neighbor, it updates the local
topology information.
3) If a standby SRPU is available on the member device, the active SRPU synchronizes its recorded
topology information to the standby SRPU to ensure that the topology information on both cards is
consistent.
After topology collection lasts for a period of time, all members have obtained the complete topology
information (known as topology convergence), and then 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 merge. The master is elected based on
the rules below, in the order specified. If the first rule does not apply, a second rule is tried, and so on,
until the only winner is found.
z The current master, even if a new member has a higher priority. (When an IRF virtual device is
being formed, all member devices consider themselves as the master, so this principle is skipped)
z A member with a higher priority.
z A member with the longest system up-time. (The system up-time information of each member
device is delivered through IRF hello packets)
z A member with the lowest bridge MAC address.
Then, the IRF virtual device is formed and enters the next stage: IRF virtual device management and
maintenance.