I have the following questions on Catalyst 4500E hot-swappable hardware components;

  1. Is it possible to insert/pull out line cards to or from powered on chassis?
  2. Is it possible to insert redundant supervisor to powered on chassis?
  3. Is it possible to pull out one supervisor if two inserted?
  4. Can I cause any damage to chassis or line cards?

4 Answers 4


4500 line cards are hot swapable, so the answer to the first three questions is yes (assuming a 45xxR chassis).

A couple of caveats, for question 2, the supervisor has to meet the requirements for redundany. For instance, you would not be able to insert a Sup7 in a chassis with a SupIV. Additional configuration may be required as well to enable the redundancy properly.

For question 3, you shouldn't remove an active supervisor (while you can, this isn't best practice). If the supervisor you wish to remove is currently active, failover to the standby supervisor first.

The answer to the last question is yes, you can cause damage to the chassis and/or line card if you insert them incorretly (i.e. this has nothing to do with the chassis being running, but a purely mechanical problem). The levers should be open when inserted, the card should glide in easily until the levers start to close by themselves, and the final insertion should be done with the levers. If you have to use A LOT of force, it may not be aligned properly and you could result in damage.

On the 4500s, you also need to make sure you are using the proper slots. Do not try to install a supervisor module in a linecard slot or vice versa.

  • My goal was to understand if all modules are hot swapable. We are going to make stress tests and check supervisor redundancy. According to this we thought about hardware supervisor pull out. May 23, 2013 at 13:43
  • For redundancy tests, then yes, you can do so as you are trying to simulate a "worst case." I would also make sure you are in SSO mode rather than RPR mode.
    – YLearn
    May 23, 2013 at 13:48

YLearn and javano covered the question nicely.

I'd just like to add that most common reason of failing hot-swap is actually operator using too little force causing long bus stall.

The insertion can last quite finite time and by inserting too slowly/lightly you can trigger long bus stall which will affect other linecards as well

  • 1
    FYI, bus stalls are specific to the Catalyst 6500, due to the way a long pin on the LC interacts with the bus. It is the long pin on those LCs that can cause a bus stall, if the card is inserted slowly. May 24, 2013 at 8:54
  • Thanks Mike. With my very limited EE clues, isn't the insertion EE wise complex problem generally? Is 4500 safe from cascading fault due to improper insertion, and worst case scenario is just new linecard not coming up?
    – ytti
    May 24, 2013 at 9:03
  • 1
    The devil is invariably in the details... The 6500 chassis has three pins in each slot which correspond to the LC. If there is no DFC, during LC insertion the longest pin makes first contact and stalls the DBus. As the line card is pushed in further, the middle pin makes the data connection. Finally, the shortest pin removes the DBus stall and allows the chassis to continue switching.... thus, the mechanical design of Catalyst 6500 LCs (that do not have a DFC) make them more vulnerable to a bus stall... May 24, 2013 at 9:07

In the same order you have asked;

Hot-swappable power supplies and switching modules

Enables hot insertion and extraction for changes and maintenance any time without bringing down your system

hot swapping of supervisors is supported without disrupting system operation

It is obviously advised to pull out the backup one, as you runs these in a "master/backup" scenario, with the "master" syncing CEF adjacencies, RIB updates, TCAM entries etc, to the "backup". So removing the "backup" SUP typically has no effect. Removing the "master" SUP should have no effect if you have things like Nonstop Forwarding and Stateful Switchover configured, if not, your results will vary depending on your set up.

  • 4 No - These products are designed to be hot swappable (having said that, very very rarely they may malfunction. For example, pulling out a supervisor engine when you have two installed, could cause an outage, even though supervisor redundancy has been enabled with not stop forwarding etc. Sh*t happens, software does crash, so my recommendation would be to perform these supposedly "non service effecting" procedures during an announced maintenance period, just in case.).

In addition to what ytti said, the 4500 cards need quite "firm" pressure to seat properly. The extraction levers must rest all the way against the card when inserted. Make sure the cards are sliding into the "rails" properly, a twisted card can damage the card or the backplane connector

  • But don't slam the module in as hard as you can as I witnessed one time with a jr. network engineer who said another [supposedly sr.] engineer taught him to do it that way. May 23, 2013 at 23:58

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