Specifications

88 Implementing IBM System Networking 10Gb Ethernet Switches
FDB flush
When an AMP port/trunk is the blocking state, FDB flush is performed on that port/trunk. Any
time there is a change in the data path for an AMP group, the FDB entries associated with the
ports in the AMP group are flushed. This situation ensures that communication is not blocked
while obsolete FDB entries are aged out.
FDB flush is performed when an AMP link goes down, and when an AMP link comes up.
2.7.8 Stacking
A stack is a group of up to eight IBM System Networking switches (the stacking is supported
only on Virtual Fabric 10Gb Switch Module devices) that work together as a unified system.
Because the multiple members of a stack acts as a single switch entity with distributed
resources, high-availability topologies can be more easily achieved.
In Figure 2-19, a simple stack using two switches provides full redundancy in the event that
either switch fails. As shown with the servers in the example, stacking permits ports within
different physical switches to be trunked together, further enhancing
switch redundancy.
Figure 2-19 High-availability topology using stacking
A stack has the following properties, regardless of the number of switches included:
򐂰 The network views the stack as a single entity.
򐂰 The stack can be accessed and managed as a whole using standard switch IP interfaces
configured with IPv4 addresses.
򐂰 After the stacking links are established, the number of ports available in a stack equals the
total number of remaining ports of all the switches that are part of the stack.
򐂰 The number of available IP interfaces, VLANs, trunks, trunk links, and other switch
attributes are not aggregated among the switches in a stack. The totals for the stack as a
whole are the same as for any single switch configured in stand-alone mode.
Stacking requirements
Before IBM System Networking switches can form a stack, they must meet the
following requirements:
򐂰 All switches must be the same model (Virtual Fabric 10Gb Switch Module).
򐂰 Each switch must be installed with IBM Networking OS Version 6.5 or later. The same
release version is not required, as the master switch pushes a firmware image to each
switch that is part of the stack.