3com S7906E Installationsanweisungen

 

1-6 

An IRF typically has a daisy chain connection, that is, IRF-port1 of a device is connected to IRF-port2 of 

another device, and the two devices are connected to form a single straight connection, as shown in 

Figure 1-5 Physical connections of IRF 

IRF-port1

IRF-port2

IRF

Master

Slave

 

 

The orange line in the figure represents the IRF link, which is different from a common Ethernet network 

cable. An IRF link can be composed of either one physical cable or multiple physical links. 

Each member in an IRF exchanges hello packets with the directly connected neighbors to collect 

topology of the entire IRF. The IRF hello packets carry topology information, including IRF port 

connection states, member IDs, priorities, and bridge MAC addresses. 

Each member is managed by its local active SRPU, which records its known topology information 

locally. At the initiation of the device startup, the local active SRPU records topology information of the 

local device. When an IRF port of a member becomes up, the local active SRPU performs the following 

operations: 

1)  Sends its known topology information from this port periodically.  

2)  Upon receiving the topology information from the directly connected neighbor, it updates the local 

topology information.  

3)  If there is a local standby SRPU configured, the local active SRPU synchronizes its recorded 

topology information to the local standby SRPU to ensure that the topology information on both 

SRPUs 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 will enter the next stage: role election. 

The process of defining the role (master or slave) of IRF members is role election. 

Role election is held when the topology changes, such as, forming an IRF, adding a new member, 

leaving or failure of the master, or IRF merge. The role election principles are as follows: 

z 

The current master wins, even if a new member has a higher priority. (When an IRF is being formed, 

there is no master, and all member devices consider themselves as the master, so this principle will 

be skipped) 

z 

A member with a higher priority wins. 

z 

A member with the longest system up-time wins. (The system up-time information of each device is 

delivered through IRF hello packets) 

z 

A member with the lowest bridge MAC address wins. 

The master is elected according to the above principles one by one, until the only winner is found out.