[CentOS] Replacing gateway, is it bad idea?

Wed Nov 30 11:49:47 UTC 2011
Dennis Jacobfeuerborn <dennisml at conversis.de>

On 11/30/2011 10:09 AM, John R Pierce wrote:
> On 11/30/11 12:59 AM, Fajar Priyanto wrote:
>> How fast the Switches can recognize the new mac? Any other pitfall?
> within seconds.  or faster.  and the client's ARP caches expire nearly
> as fast.
> its not the switches you care about as much as the DHCP leases for your
> clients.  if you can copy the dhcp leases file over, that will save a
> lot of grief.

If you want to plug the new system in the same port the old system was 
plugged in before then depending on the switch and how it is configured it 
can take 30-60 seconds to change the switch port to a forwarding state. 
During that time the switch will send put out STP requests to determine if 
the newly attached device is also a switch. Once these time out it will 
assume the new device is a regular system and change the port to a 
forwarding state.

You can prevent this by enabline something like "PortFast" for that port 
which tells the switch to simply assume that only regular devices will be 
connected to that port and to immediately change the port to a forwarding 

See for example: