Configuration Guide User guide

330 FastIron Configuration Guide
53-1002494-02
Hitless stacking
Non-supported hitless stacking events
The following events are not supported by hitless stacking. These events require a software reload,
resulting in an impact to data traffic.
• Unit ID change – When a stack is formed or when a unit is renumbered using secure-setup.
• Stack merge – When the old Active Controller comes back up, it reboots. If it has fewer number
of members than the Active Controller, it loses the election, regardless of its priority. If it has a
higher priority, it becomes the Standby Controller after the reboot and is synchronized with the
Active Controller. Next, a switchover occurs and it becomes the new Active Controller.
Supported hitless stacking protocols and services
Table 56 lists the services and protocols that are supported by hitless stacking. Table 56 also
highlights the impact of a hitless switchover or failover to the system’s major functions.
NOTE
Services and protocols that are not listed in Table 56 will encounter disruptions, but will resume
normal operation once the new Active Controller is back up and running.
TABLE 56 Hitless-supported services and protocols
Traffic type Supported protocols and services Impact
Layer 2 switched traffic,
including unicast and
multicast
+
System-level
+
Layer 4
• 802.1p and 802.1Q
• 802.3ad – LACP
• 802.3af – PoE
• 802.3at – PoE+
• DSCP honoring and Diffserv
• Dual-mode VLAN
• IGMP v1, v2, and v3 snooping
• IPv4 ACLs
• Layer 2 switching (VLAN and 802.1Q-in-Q)
• MAC-based VLANs
• MLD v1 and v2 snooping
• MRP
• Multiple spanning tree (MSTP)
• Physical port/link state
• PIM SM snooping
• Port mirroring and monitoring
• Port trunking
• Rapid spanning tree (RSTP)
• Spanning tree (STP)
• ToS-based QoS
• Policy Based Routing
• Traffic policies
• UDLD
• VSRP
Layer 2 switched traffic is not impacted during a hitless
stacking event. All existing switched traffic flows
continue uninterrupted.
New switched flows are not learned by the switch
during the switchover process and are flooded to the
VLAN members in hardware. After the new Active
Controller becomes operational, new switched flows
are learned and forwarded accordingly. The Layer 2
control protocol states are not interrupted during the
switchover process.