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New Member

Segment same network in VLAN´s

It´s possible segment on network 150.150.0.0/16 in two or three VLAN´s ?

My network use 6509(IOS native mode) and 2950(IOS 12.1)

  • Other Network Infrastructure Subjects
1 ACCEPTED SOLUTION

Accepted Solutions
Bronze

Re: Segment same network in VLAN´s

No, the router will only know about one of vlans so the proxy arp cannot be used on the others. The logical interfaces int the msfc (router) represent the different vlans that are to be "routed". The IP address and mask assigned to each interface define the address space that the interface routes for. The address spaces cannont overlap between interfaces in the same router. The router would not know which logical interface to send traffic out. If you want to use the same address space in each vlan then only one of the vlans can be defined in the router as a logical interface that can be routed. They would all be defined in the switch but because the switch does not know any thing about the layer 3 addresses being used in the vlan.

6 REPLIES
Bronze

Re: Segment same network in VLAN´s

Use mask of 255.255.192.0 and you'll get 4 networks of 16381 hosts.

150.150.0.0/18

150.150.64.0/18

150.150.128.0/18

150.150.192.0/18

Basically you subnet by dividing nets in half so you get an even number of networks. However, if you want 3 you can divide it in half then divide one of those halfs again. In that case you get one network with 32765 hosts and two with 16381.

150.150.0.0/17

150.150.128.0/18

150.150.192.0/18

New Member

Re: Segment same network in VLAN´s

I need the same network, 150.150.0.0/16, in many VLAN´S and one this VLAN´S is the servers.

The trafic go the vlan server to another and vice versa but never intervlan´s.

It´s possibilite with my network equipament ?

Bronze

Re: Segment same network in VLAN´s

It sounds like you saying you want the same IP address space in many vlans. Yes you can do this but the vlans will not be able to see each other. You can only route one of them and only to go to some other network besides the 150.150.0.0 vlans. They will all be isolated from each other and all but one isolated from the world.

New Member

Re: Segment same network in VLAN´s

And the options ip local-proxy-arp in any vlan.

Resolve this problem or no ???

Bronze

Re: Segment same network in VLAN´s

No, the router will only know about one of vlans so the proxy arp cannot be used on the others. The logical interfaces int the msfc (router) represent the different vlans that are to be "routed". The IP address and mask assigned to each interface define the address space that the interface ro;utes for. the address spaces cannont overlap between interfaces in the same router. The router would not know which logical interface to send traffic out. If you want to use the same address space in each vlan then only one of the vlans can be defined in the router as a logical interface that can be routed. They would all be defined in the switch but because the switch does not know any thing about the layer 3 addresses being used in the vlan.

Bronze

Re: Segment same network in VLAN´s

No, the router will only know about one of vlans so the proxy arp cannot be used on the others. The logical interfaces int the msfc (router) represent the different vlans that are to be "routed". The IP address and mask assigned to each interface define the address space that the interface routes for. The address spaces cannont overlap between interfaces in the same router. The router would not know which logical interface to send traffic out. If you want to use the same address space in each vlan then only one of the vlans can be defined in the router as a logical interface that can be routed. They would all be defined in the switch but because the switch does not know any thing about the layer 3 addresses being used in the vlan.

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