Stack Split Detection (SSP) Managing OmniSwitch 6450 Stacks
page 7-40 OmniSwitch 6450 Hardware Users Guide September 2015
Use the stack split-protection guard-timer and the stack split-protection commands to configure the
guard timer and enable/disable SSP.
Automatic Recovery
If the stacking link recovers and the sub-stack reconnects to the active stack the sub-stack will automati-
cally reboot. The protection units will come up in the protection state; however they will now be part of
the active stack but their front panel ports will still be disabled. The primary of the combined stack will
detect that there are new elements in the protection state. The primary will wait for the guard timer to
expire and will then bring one element at a time from the protection state until all elements are active.
Once complete, the primary will generate a trap indicating the stack has been recovered.
Stack Split Example
1. Stack split detected, substack transitions to PROTECTION state.
2. Sub-stack front panel ports shutdown to avoid duplicate addresses on network
3. PROTECTION PDUs sent by sub-stack to active-stack over helper linkagg.
4. Active-stack sends trap indicating stack split.
1
Normal Opera-
tion
SSP PDUs sent over helper linkagg and relayed by helper switch.
2
Stack Split
Helper switch.
Sub-stack
Active-stack
3
Recovery
Helper switch.
1. Stacking link recovers, new elements detected by Primary.
2. Manual Recovery - Administrator disables/enables SSP to clear PROTECTION state.
3. Automatic Recovery - After guard-timer expiration, Primary will bring up elements one at a time.
4. Once stack is functioning, Primary will send trap indicating stack recovery.
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