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Managing a Switch Stack
153
What is Stacking Standby?
A standby unit is preconfigured in the stack. If the current stack master fails,
the standby unit becomes the stack master. If no switch is pre-configured as
the standby unit, the software automatically selects a standby unit from the
existing stack units.
When the failed master resumes normal operation, it joins the stack as a
member (not a master) if the new stack master has already been elected.
The stack master copies its running configuration to the standby unit
whenever it changes (subject to some restrictions to reduce overhead). This
enables the standby unit to take over the stack operation with minimal
interruption if the stack master becomes unavailable.
Operational state synchronization also occurs:
• when you save the running configuration to the startup configuration on
the stack master.
• when the backup unit changes.
What is Nonstop Forwarding?
Networking devices are often described in terms of three semi-independent
functions called the forwarding plane, the control plane, and the
management plane. The forwarding plane forwards data packets and is
implemented in hardware. The control plane is the set of protocols that
determine how the forwarding plane should forward packets, deciding which
data packets are allowed to be forwarded and where they should go.
Application software on the stack master acts as the control plane. The
management plane is application software running on the stack master that
provides interfaces allowing a network administrator to configure the device.
The Nonstop Forwarding (NSF) feature allows the forwarding plane of stack
units to continue to forward packets while the control and management
planes restart as a result of a power failure, hardware failure, or software fault
on the stack master. This type of operation is called nonstop forwarding.
When the stack master fails, only the switch ASICs on the stack master need
to be restarted.
To prevent adjacent networking devices from rerouting traffic around the
restarting device, the NSF feature uses the following three techniques:
Summary of Contents for PowerConnect M6220
Page 52: ...52 Introduction ...
Page 86: ...86 Switch Features ...
Page 100: ...100 Hardware Overview ...
Page 116: ...116 Using the Command Line Interface ...
Page 121: ...Default Settings 121 ...
Page 122: ...122 Default Settings ...
Page 142: ...142 Setting Basic Network Information ...
Page 206: ...206 Configuring Authentication Authorization and Accounting ...
Page 292: ...292 Managing General System Settings Figure 11 31 Verify MOTD ...
Page 296: ...296 Managing General System Settings ...
Page 332: ...332 Configuring SNMP ...
Page 408: ...408 Monitoring Switch Traffic ...
Page 560: ...560 Configuring Access Control Lists ...
Page 591: ...Configuring VLANs 591 Figure 21 17 GVRP Port Parameters Table ...
Page 597: ...Configuring VLANs 597 Figure 21 24 Double VLAN Port Parameter Table ...
Page 693: ...Configuring Port Based Traffic Control 693 Figure 24 3 Storm Control 5 Click Apply ...
Page 780: ...780 Configuring Connectivity Fault Management ...
Page 804: ...804 Snooping and Inspecting Traffic Figure 27 17 DAI Interface Configuration Summary ...
Page 818: ...818 Snooping and Inspecting Traffic ...
Page 836: ...836 Configuring Link Aggregation ...
Page 860: ...860 Configuring Data Center Bridging Features ...
Page 906: ...906 Configuring DHCP Server Settings ...
Page 940: ...940 Configuring L2 and L3 Relay Features Figure 34 3 DHCP Relay Interface Summary ...
Page 1080: ...1080 Configuring VRRP ...
Page 1104: ...1104 Configuring IPv6 Routing ...
Page 1131: ...Configuring Differentiated Services 1131 Figure 40 5 DiffServ Class Criteria ...
Page 1158: ...1158 Configuring Class of Service Figure 41 1 Mapping Table Configuration CoS 802 1P ...
Page 1174: ...1174 Configuring Auto VoIP Figure 42 2 Auto VoIP Interface Configuration ...
Page 1240: ...1240 Managing IPv4 and IPv6 Multicast Figure 43 51 DVMRP Next Hop Summary ...
Page 1266: ...1266 Managing IPv4 and IPv6 Multicast ...
Page 1274: ...1274 System Process Definitions ...
Page 1294: ...1294 Index ...