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Cisco managed switches -- running out of IP addresses ?

Posted on 2015-02-12
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Last Modified: 2016-11-23
Are below valid options since I am
running out of IPs on 255.255.255.0 subnet ?

If so, which do you prefer and how can I setup
my Cisco Catalyst 3560 switches to accept
both 192.168.14.x and 192.168.15.x ?
============================================================
Details
  ** old managed Cisco Catalyst 3560
       switches all on 192.168.14.x network
  ** have old Windows Server 2003
        DHCP server, will upgrade soon
  ** do NOT need to segregate traffic,
        just need more IPs
  ** using Dell SonicWall firewall
============================================================
Option #1
  ** make SUPERSCOPE on Windows Server
       2003 DHCP server with new 192.168.15.x network
============================================================
Option #2
  ** change STATIC IP servers, switches, etc
       to new 255.255.255.254 subnet
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Question by:finance_teacher
6 Comments
 
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by:
Matt earned 84 total points
ID: 40606107
If you define VLANs on 3560 with gateway 192.168.14.1 for 192.168.14.X and 192.168.15.1 for 192.168.15.X, then you can access the switch via both IP addresses.
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by:Harold
Harold earned 84 total points
ID: 40606171
As Matt, explained you can create VLANs  on a switch, for each subnet, DHCP on the switch in the ranges and assign what ports you want on what subnet to the relevant VLAN. If DHCP is on the server as well, make sure you're not overlapping IP ranges, big headache.

If you're just needing to add IPs to the existing ranges, use /20, 21 or 22, this will give more addresses.

Are you wanting to put all DHCP in your switching or spread across servers and switches?
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by:tmoore1962
tmoore1962 earned 83 total points
ID: 40606178
you could also just expand your scope, change subnet from 255.255.255.0 to 255.255.252.0 this would expand your network to cover 192.168.12.0 to 192.168.15.255 You then expand your DHCP scope within this subnet to give more avail leases if needed ie make your scope from 13.1 to 14.xxx use the  entire .15 for switches / AP's  use the .12 for servers / printers / other static devices.  Should give you plenty of growth going from a /24 network.
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by:Stephen Berk
Stephen Berk earned 83 total points
ID: 40606494
Super scope. But you will need to change the subnet mask of your static addresses to match the superscope.
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by:costanos
costanos earned 83 total points
ID: 40606651
Pretty much what other people are saying is correct.  To make 192.168.14.x become 192.168.14.x - 192.168.15.x you would just need to change it to 255.255.254.0 aka 192.168.14.0 /23.
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by:giltjr
giltjr earned 83 total points
ID: 40608461
My personal opinion  would be to setup two VLAN's each with their own subnet.  One being the current 192.168.14.0/24 and a second one of your choice.  Make sure NEITHER VLAN is VLAN 1.  VLAN 1 is typically the default VLAN used by Cisco switches to communicate information about each other to each other, and you want to keep as much traffic as possible off of VLAN 1 as you can.

Setup all of the switches with new IP addresses on the new VLAN/subnet. This will keep your management and "user" traffic separate from each other.

Since you will have two VLAN's you will need to enable routing on the switches and setup trunking for any switch to switch connections.
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