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Preparation For Switch Failure?

I've been tasked by my IT director with developing a plan for when a switch fails at our two locations. Redundancy and HA aren't part of this plan. Instead, I've been asked to focus on replacing a failed switch with an identical appliance. We have three 3560G 48 port swtiches in one locaiton and seven 3750Gs at our other location. We've purchased one of each as a backup. I understand the method of configuring the replacement switches in the event of a failure, but what I'm stuck on is developing a plan that presents the quickest most efficient and clean process. We do have room in our rack at the location utilizing 3560G switches, but no room in the rack where the 3750s are housed.

How have you planned for switch failure? What are the best practices?

9 REPLIES

Preparation For Switch Failure?

Hi Charles,

This is 'cold' standby procedure. This way you definitely expect to have downtime incase production device failure but try to minimize the down time. As you purchased one of each as back up (which most companies do), my suggestion-

-> upload the IOS that is similar to existing production units (as that IOS/features are working fine)

->Keep up to date TFTP backup of the production switches.

-> I assume all prod switches have similar configuration except for IP addresses (description on port does not matter when there is real outage). Prepare the standby switches with existing configuration of one of the switch (you can use different  management IP or same IP as it will be cold standby).

-> label them with the IP used/switch configuration used and you can mount them (based on space in the cabinet) or keeo it aside.

-> Incase if you mount it (ex;3560), make sure production 3560 port cables able to reach this swich ports or else buy longer cables and keep them ready to use.

Thx

MS

Preparation For Switch Failure?

mvsheik123, provided some very good ideas to help you.

This will also depend on how far apart these two locations are?

Also, what your Network Topology looks like as well.

I would configure a switch already powered on, and configure it like any of your others, if they are very similar..

You can either not include cables already or not, one again, this depends on which switch, and where in the topology it fails.

All you would have to do, is just plug in the switch cables to go wherever you need them to, and you're good to go.

That's really the quickest and easiest method in your situation.

I saw you ahve some 3750, so you could just install one in your currently operating stack (depending on how many stacks you have, and where they are located in your topology), and provison the switch like the others, then all you have to do is move cables, confiure a few things most likely and you're good.

New Member

Preparation For Switch Failure?

Thank you for your input.

I'm new to Cisco switching and routing, so bare with me. The 3560 switches do have similar configurations. The only differences I can see are:

1. The port configurations

2. One has spanning-tree vlan 1-4094 priority 0 and the others don't

3. One has a TP-self-signed certificate while the other two have HTTPS_SS_Cert_Keypair

4. Obviously the IP Addressing

5. Two have NTP servers configured and one does not.

Would I be better off leaving the switch without a configuration and just keep fresh backups of the config files so the respective file can be imported into the replacement switch when one fails?

Thanks again for your help?

Preparation For Switch Failure?

Would I be better off leaving the switch without a configuration and just keep fresh backups of the config files so the respective file can be imported into the replacement switch when one fails?

Sounds good. Make sure you connect the cable back into the same ports (1 ->1, 2->2 etc). Label all production  switch port cables.

hth

MS

Hall of Fame Super Gold

Re: Preparation For Switch Failure?

Ok, let me give you a "funky" method which incorporates two processes:  Zero-Touch SmartInstall and EEM.

Let's start with the easy part:  EEM

For this process to work, you need to have a non-MS TFTP server.  Linux/Unix is preferred because of the way the files are written.  This EEM script is invoked when someone saves the config of your appliance.  When this happens the appliance will automatically send a copy of the configuration to the remote TFTP server of your choice.  The filename will be named is this syntax:  Switch_name-Month-Day-Hour-Minues-Second-Timezone-version

Another thing, if no one has saved the config for a week, then the switch will still copy the startup-config to the TFTP server of your choice. 

Ok, here's the script:

archive

log config

   logging enable

   hidekeys

path tftp:///$h-

write-memory

time-period 10080

Ok, now this solves the problem of an "updated config".  Next, the replacement.

There's a process called Zero-Touch SmartInstall.  What this does:

1.  You have a new switch, fresh from the box, no configuration whatsoever;

2.  You connect the new switch to the Director (explained later) via the ethernet port;

3.  You power up the new switch and YOU DO NOTHING;

4.  The new switch will talk to the Director.  The Director will provide the new switch with an IP Address (via VLAN 1).  The Director determines that the new switch does not have a config and running an IOS with is not "standard".  The Director will push the config to the new switch's startup-config (the running-config still empty) and then the IOS will get pushed to the new switch;

5.  The new switch will reboot with the correct IOS specified and a full-working configuration.

Ok.  So let's run the scenario.  You have a failed switch at either one of the sites.

Using the above EEM, you have a full-blown working config.  The latest one to boot!

The site with a dead switch has a switch capable of being a Director and a TFTP server.  So you copy the working config from your TFTP server to the Director.  Configure the Director switch.  Cisco sends the replacement unit to the site (instead of your location).  You instruct the person on-site to connect the new switch to the Director and power up the switch.  New switch gets the working config and an IOS upgrade/downgrade.

All in all, your new replacment switch is ready in 30 minutes.  Tops.

New Member

Preparation For Switch Failure?

How would I designate a 3560 switch to be a Director? What's entailed?

Thanks.

Hall of Fame Super Gold

Re: Preparation For Switch Failure?

How would I designate a 3560 switch to be a Director? What's entailed?

Go here:  Zero-Touch SmartInstall

Re: Preparation For Switch Failure?

Hello

Are these switches are stacked?

Res
Paul

Sent from Cisco Technical Support iPad App

Please don't forget to rate any posts that have been helpful. Thanks.
New Member

Preparation For Switch Failure?

Yes, the 3750s are stacked.

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