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Ex3300 virtual chassis split

[ Edited ]
2 weeks ago

Hello all,

im studying virtual chassis concepts,  as i don't have required lab to test my scenarios. can you guys please help me with my questions?  please check topology of 4-member VC:

 

1)  split detection is enabled:   what happens if vc-port broken on Master, does it will cause any issue to VC? as connection is redundant, hope there will be no issue, as one of link broken(let say towards Backup) still master has redundant VC connection is there with(towards linecard directly), as far as i know there will be no issues? correct me if im wrong

 

2) split detection is enabled: suppose, if "Backup" member got failed to boot/dead completely. next linecard will take role as "Backup" (as split is detected in VC, as there is change in topology , Both member0(master) and linecard(member2) will start mastreship algorithm. As already in master, priroity is defined "Master" will retain it's role, now after "Backup" is dead then "Linecard" with priority 253 ==> will takeover as "Backup"?)

or as split detection is enabled and master consider there is split and will push it's own master role to line card?

 

In device only master-ship priority settings are defined:

show configuration virtual-chassis | display set

set virtual-chassis member 0 mastership-priority 255
set virtual-chassis member 1 mastership-priority 254
set virtual-chassis member 2 mastership-priority 253
set virtual-chassis member 3 mastership-priority 252

vctopology.jpg

 

Thanks already for help Smiley Happy

 



2 REPLIES 2
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Re: Ex3300 virtual chassis split

2 weeks ago

Hi madhutraining,

 

The split detection feature avoids a dual master scenario when a member is detached from the VC.

 

In a Virtual Chassis configuration, switches are connected together to form a unit that is managed as a single chassis. If there is a disruption to the Virtual Chassis configuration due to member switches failing or being removed from the configuration, the Virtual Chassis configuration splits into two separate Virtual Chassis. This situation could cause disruptions in the network if the two separate configurations share common resources, such as global IP addresses. The split and merge feature provides a method to prevent the separate Virtual Chassis configurations from adversely affecting the network and also allows the two parts to merge back into a single Virtual Chassis configuration.

 

While the Virtual Chassis split detection implementation is desirable in most cases, there are rare situations that
could lead to all parts of a Virtual Chassis split being rendered inactive. For example, if a split occurs and the resulting segments have an equal number of Virtual Chassis members, the original Master and Backup switches do not fall into the same split segment, and the original Backup switch is part of the failure that triggers the split, the resulting split parts would have no “active” members. 

 

I found one very useful document to answer your queries. In addition to your conditions of master and backup failures, it also has an additional condition of what happens when the line card fails. Please give it a read.

https://kb.juniper.net/InfoCenter/index?page=content&id=KB19732&cat=EX4200_1&actp=LIST

 

Hope this helps Smiley Happy

 

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Re: Ex3300 virtual chassis split

2 weeks ago

Hi madhutraining,

 

Also, considering that your question is pertaining to one situation only, the below document has all details covering various situations and conditions about the split and merge and how it functions in Virtual Chassis. This should give a complete clarity of how split and merge works.

 

https://www.juniper.net/documentation/en_US/junos/topics/concept/virtual-chassis-ex4200-split-merge....

 

Please give it a read. 

 

Hope this helps Smiley Happy

 

Please mark this "Accepted Solution" if this solves your doubts.

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