Two Cisco 3850 in a Stack

[gilsbar]

I have two 3850s in a stack and noticed that they are in an Active/ Standby configuration.  Is this normal?  I have never used just 2 switches in a stack before and used to seeing Master and Members and not Active Standby.

Does this mean the standby switch is not live untl the Active one fails?

I am a bit confused as to why this is Active/Standby as opposed to Master/member.  If Active/Standby is correct can I convert it to Master Member? I need all ports to be live.

[Brandon Buffin]

Each switch stack has one active switch and one standby switch. The active switch controls the switch stack and controls global and interface level features. The standby switch takes over if the active switch is unavailable. After the election of the active and standby switches, other switches in the stack become members. Since you only have two switches you will only see an active and a standby switch - no members.

Take a look at this link for more detail:

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3850/software/release/3se/ha_stack_manager/configuration_guide/b_hastck_3se_3850_cg/b_hastck_3se_3850_cg_chapter_010.html#con_1228109

Brandon

[gilsbar]

Thank you for the reply.  

Are all ports live even though the switch is marked as standby?  Any idea how long it take to failover the master role once the stack loses a switch?

[Brandon Buffin · Accepted solution]

Yes, all ports are active. Only the control stack control function is in standby. If the active switch fails, the switch ports on other member switches continue to function. The active/standby election will take place again and the new active switch will take over stack control functions. I don't know the exact time - should be a matter of seconds. See the following quote from the link above.

"After election, the new active switch becomes available after a few seconds. In the meantime, the switch stack uses the forwarding tables in memory to minimize network disruption. The physical interfaces on the other available stack members are not affected during a new active switch election and reset."

Brandon

[Ganesh Hariharan · Accepted solution]

I have two 3850s in a stack and noticed that they are in an Active/ Standby configuration.  Is this normal?  I have never used just 2 switches in a stack before and used to seeing Master and Members and not Active Standby.Does this mean the standby switch is not live untl the Active one fails?I am a bit confused as to why this is Active/Standby as opposed to Master/member.  If Active/Standby is correct can I convert it to Master Member? I need all ports to be live.

Hello ,

There is bit change in technology for cisco 3850 switches which are in stack compare to old one with master and slave concept, With 3850 it have  standby fully synced with the master for high availability which is in line with N3k platform series of switches.

Consider of thinking dual sup concept in 4500 series switches , if you check show redundacny you will SSO or hot standby . That measn standby is activey waiting to take control in case of master fails. So to answer your question, they kind of work together 

You can use the following commands to verify your stacking:

3850-stack#show switch detail

3850-stack#show switch stack-ports summary

Hope it Helps..

-GI

Rate if it Helps..

[gilsbar]

There is bit change in technology for cisco 3850 switches which are in stack compare to old one with master and slave concept, With 3850 it have  standby fully synced with the master for high availability which is in line with N3k platform series of switches.

Thank you for the SSO information that does make more sense.  I setup our 4500s in SSO eariler in the year so I get the concept.  Most of my other switches have been 2960s that don't have this functionality so I was a bit confused about why I was seeing Active/Standby vs Master/Member. Normally I associate the word "Standby" with something not being live, but ready to go in case there is a problem.