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Frequently asked questions about VC master election mechanism in EX switches



Article ID: KB16290 KB Last Updated: 04 Mar 2017Version: 2.0
 Frequently asked questions about VC master election mechanism
 Frequently asked questions about VC master election mechanism
Q1. How is the master member is elected?
The election algorithm follows the below mentioned steps from 1 through 4 in the following order. Once a master is chosen on a prior step, the algorithm stops and does not execute the remaining steps.

1 . Chooses the member with the highest user-configured mastership priority (255 is the highest possible value).
2 . Chooses the member that was master the last time the Virtual Chassis configuration booted.
3 . Chooses the member that has been included in the VC configuration for the longest period of time.
     (For this to be a deciding factor, there has to be a minimum time lapse of one minute between the power-ons of the individual interconnected member switches.)
4 . Chooses the member with the lowest MAC address.

Q2. Where is virtual chassis configuration is stored within the sytem?
A2. In the directory /config/vchassis. System checks the file while booting up.The file will be updated in accordance with VC configuration and topology.

Q3. Where are the serial number and mac-address infomation registered ?
A3. They are saved in the system's non-volatile Flash memory. The information is contained in the vc.tlv.db file under /config/vchassis directory.

Q4. As VCCPD detects the neighbor by hello mechanism of ISIS protocol, Is each PFE now considered to be ISIS node?
A4. In a VC setup, a PFE is not a node but a FPC is considered to be a node

Q5. How does hello packets help in forming VC setup?
A5. Hello packets carry information about the FPC [e.g.. Number of PFEs, Connectivity between PFEs, etc]
When VCCPd receives the information from all FPCs, it creates PFE specific graph

Q6. Does VCCPD run on each member of the VC including the Linecard?
A6. Yes, VCCPD process needs to be run on all members of a virtual chassis setup.
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