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New Member

Adding a second SUP IV to 4507R

I am looking at adding a second sup iv to a current 4507R switch. I am under the impression that by adding the second SUP I can then do an IOS upgrade on one SUP and then the other without having to do a power cycle/reload on the switch it’s self. The goal is to get redundancy in the switch. I will be purchasing a second 4507 switch also and building this into a HSRP setup for the multitude of vlans that are currently on the existing switch.

I am hoping that by also having dual SUP’s in each switch I will be able to do IOS upgrades with actually having to down the switch it’s self thus giving me the greatest uptime.

If I am wrong in this assumption can someone point me to some documentation that shows you will still have to power cycle the switch to complete an upgrade as this will save the cost of 2 SUP’s or about $20,000.00


New Member

Re: Adding a second SUP IV to 4507R

With 2 Sup engines, we can use route processor redundancy (RPR) and stateful switchover (SSO) to shortening the switchover time of 30 seconds or longer in RPR mode & subseconds in SSO mode if the active supervisor engine fails or if a manual switchover is performed.

On your IOS upgrade question, you still have to reload the switch to activate the new image. This can be done in a manner that will minimize the down time. Details of this can be found in



New Member



            Your response does not appear to directly match the question asked.

It is well documented how to upgrade iOS when both SUP are already in place....common.

Cisco Employee



I dont think with two SUP cards you will have to perform a reload on the router. when you add a new standby SUP, it is possible that it might not be running the correct code. It is better to break it into rommon mode itself and perform the upgrade for the standby. 

Since the standby and Active will not be running the same code, they will run in RPR mode. Once you reload the active SUP card by setting the boot statement to the correct IOS image, the standby will take over and boot up with the upgraded image. This way, by the time the new standby (which was previously active) comes up, the router will again be in SSO mode.

That is the best part of having two SUP cards on the router so that you can perform non-disruptive upgrades.

You might also look into the option of ISSU upgrade.

Hope this helps.



New Member

this was 100% simpler then it

this was 100% simpler then it seems.

Step 1.  confirm your NEW sup has the same IOS version as the existing SUP.

Step 2.  boot it in a LAB and make sure it does NOT have a config on it.

Step 3.  Plug it into the production system (does not cause any outage effect)

Step 4.  From console,  go to conf t :  Redun \n   mode sso \n exit \n   wr me \n

Step 5.  SHOW MODULE this for 15 minutes and WATCH the results transition from RPR mode to SSO mode .....that test with a manual fail over, fail back once closed

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