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What do I need to consider when copying a configuration file over to a new switch?

Posted on 2013-05-21
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Last Modified: 2013-05-28
I am adding a switch to our network.  I am going to connect a C3560-IPBASEK9-M to an existing C2960-LANBASE-M.
At first, I tried loading an existing configuration from a similar switch to the 3560. This is a fairly simple network and all switches are configured similiarly.  Simply copying the config did not work.  
After some reading, I learned that it would probably be best not to copy over the NTP commands, so I can enter them, allowing the new switch to set its own ‘ntp clock-period’.
I learned that aside from deleting any existing vlan.dat file, I should start the switch in ‘transparent mode’ and then enter the vtp domain and password and set it to client mode.
I read that I should not use ‘spanning tree’ or ‘portfast’ on the ports connecting the two switches.  (Not that I was)
Although I believe both switches have auto-sensing and don’t need a cross-over cable, I think I will use one anyway.
I figured out on my own, that it would probably be best to create any banners manually.  It seems the control character causes some issues if copied.

Is it okay to copy over the mls qos commands as is?
Are there any other considerations I should make when copying a config file from one switch to another?
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Question by:tmaususer
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by:Akinsd
Akinsd earned 250 total points
ID: 39184410
There is nothing wrong with copying config a from one switch to another. The only issues you might encounter are
1. They both will have the same host name
2. They both will have the same virtual IP  

When copying configs, VLAN.dat file is not copied over.  When adding a used switch, just make sure to delete the vlan.dat file and reboot, then check spanning tree related issue (eg, switch becoming root bridge)

You can edit the config before pasting and change IP address, host name etc.

There is a chance you are pasting in privilege mode, if so, switch to config mode (conf t) then paste the config

Lastly, conflicting features will not copy over, eg ipv6, crypto etc. the physical components and they IOS features that match are the settings that will cross.

Again, since all your configurations are similar like you said, I don't see any issues copying configs from one switch to another. Best time saving practice is to have a template for your switches. This will usually include banners, line config (console and cry), ntp settings and server (time synchronization) etc. imagine if  you have 500 new switches to configure.....
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by:tmaususer
ID: 39184490
Okay, thanks!  I did edit the hostname and ip before copy it over.
Would you say it is best to copy the modified config file from TFTP to Start, and then reload the switch?
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by:tmaususer
ID: 39184494
For got to mention that next time I will confirm I am in conf mode.
Again, thanks.
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by:corower
ID: 39186951
you mentioned "crossover cable". it should be used only if you are connecting old (10+) years hardware, that is not able to do auto-mdi. (and at 10 or 100 Mbit). if at least one of your switches is auto-mdi capable, or if they connect at 1G speeds (or higher), do not use crossover cables. at 1G or higher speeds all four twisted pairs in cable are used, so you will need a specially crafted crossver (that crosses all 4 pairs). however, since 1998 all 1G interfaces are required to have auto-mdi capabilities. so, stick with stright cables.
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by:tmaususer
ID: 39187140
Thanks for the tip corower.  I did not realize that crossover cables used for that application are different.  
Would you say it is best to copy the modified config file from TFTP to Start, and then reload the switch?
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corower earned 250 total points
ID: 39189200
tmauser - i would say, it's quite common way of doing "push" upgrades. after all, when restoirng onfigs from backup copies - it is exactly what we do. of course, there are caveats.
0) check that config does not contain a checksumm. (i.e. it's a plaintext or xml). if it does, and you do not know the checksumming algorythm, you might be in trouble.
1) if switches are different model - check, that file formats are the same, and that switch does not leave specific signatures that must be matched.
1.1) if they're same family, but different model (like different number of ports) - check, that no excessive info is left over and no info is missing (excessive/missing ports), otherwise switch might assume that config is broken and not use it, or stop halfway.
2) if you leave donor switch in network, change all system IDs in config accordingly (at least sysname and IP - i guess, you are willing to access both old and new switches?).
3) try in sandbox first. at least - not in the core.
and good luck :)

p.s. me myself usually does it the other way - me creates a config script, that is pasted to CLI. but i'm the lazy one, and do not like using TFTP :)
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by:Akinsd
ID: 39197296
You can copy from tftp to startup config but not recommended. Open the file in text, copy everything and paste it in global config mode. The switch will accept acceptable configurations and reject the other. This is the safest way to duplicate settings between switches.

All the best
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by:tmaususer
ID: 39201084
thank you
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by:tmaususer
ID: 39201117
does it matter what the current running-config is before I paste the new one?
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by:Akinsd
ID: 39203549
Yes and no
Similar entries will be replaced while dissimilar entries are added. If you plan to duplicate the settings on both switches, you may want to erase startup config, reboot then paste your config. That way, you are starting on a new slate
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