Specifications

Chapter 6. IBM Virtual Fabric 10Gb Switch Module implementation 241
6.2.1 Stacking overview
A stack is a group of up to eight Virtual Fabric 10Gb Switch Module switches with IBM
Networking OS that work together as a unified system. 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.
6.2.2 Stacking requirements
Before IBM Networking OS 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 have IBM Networking OS V6.5 or later installed. The same release
version is not required, as the Master switch pushes a firmware image to each switch that
is part of the stack.
򐂰 The preferred stacking topology is a bidirectional ring. To achieve this topology, reserve
two external 10 Gb Ethernet ports on each switch for stacking. By default, the first two
10 Gb Ethernet ports are used.
򐂰 The cables used for connecting the switches in a stack carry low-level, inter-switch
communications and cross-stack data traffic critical to shared switching functions. Always
maintain the stability of stack links to avoid internal stack reconfiguration.
6.2.3 Stacking limitations
A VFSM with IBM Networking OS V6.5 and above can operate in one of two modes:
򐂰 Default mode, which is the regular stand-alone (or non-stacked) mode.
򐂰 Stacking mode, in which multiple physical switches aggregate functions as a single
switching device.
When in stacking mode, the following stand-alone features are not supported:
򐂰 Active Multi-Path Protocol (AMP)
򐂰 BCM rate control
򐂰 Border Gateway Protocol (BGP)
򐂰 Converge Enhanced Ethernet (CEE)
򐂰 Fibre Channel over Ethernet (FCoE)
򐂰 IGMP Relay and IGMPv3
򐂰 IPv6
򐂰 Link Layer Detection Protocol (LLDP)
򐂰 Loopback Interfaces
򐂰 MAC address notification
򐂰 MSTP
򐂰 OSPF and OSPFv3