Redesigning IP Addressing on live network

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Feb 20th, 2009
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I have a task to re-design IP addressing for 2 sites. Have these doubts,

1. At one site we are extending hosts by changing the mask from /24 to /23 for class A ip adress.

What all things i need to keep in mind when i change the mask on the router, then switch, then servers?

Will there be any kind of service disruption?

2. I will need to add a new subnet range at another site and remove the current subnet range after a month. This is also class A. Shall I plan to put the new subnet as secondary IP range or primary IP range or vice versa?

The old subnet will be taken to another site later.

ip address /23 primary

ip address 10.vvv.vv.vv /23 secondary


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Giuseppe Larosa Sat, 02/21/2009 - 01:29
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Hello Srinath,

1) when you change a subnet mask you cause service disruption for sure so you should consider to add the second network in a separate vlan as a /24 (preferred) or as secondary address (if your site cannot support multiple Vlans only in this case)

2) in this case using primary/secondary addresses in the same vlan helps to have a smooth migration.

If using DHCP you need to create a scope for new subnet

Hope to help



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