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New Member

How to assign 3 IP address to port?

I am trying to configure a port on 2811 router fa0/0 to contain 3 IP address. I tried using subinterfaces but it doesn't work. Telling me that it only works if the port is configured for vlan trunking. Is it not possible?

1 ACCEPTED SOLUTION

Accepted Solutions

Re: How to assign 3 IP address to port?

under the interface:-

ip address z.z.z.z y.y.y.y

ip address x.x.x.x w.w.w.w secondary

z.z.z.z = ip address **primary**

y.y.y.y = mask for primary IP address

x.x.x.x = ip address **secondary**

w.w.w.w = mask for secondary IP address

HTH.

8 REPLIES

Re: How to assign 3 IP address to port?

AFAIK - you can have a primary IP address and a secondary IP address - that's it. If you want to run multiple layer 3 sub-interfaces under 1 physical interface, then you need to configure the interface as a dot1q VLAN trunk.

HTH.

New Member

Re: How to assign 3 IP address to port?

I don't think I need subinterfaces. Just want 3 IP address. 1 Primary and 2 Secondary. How do I configure that?

Re: How to assign 3 IP address to port?

under the interface:-

ip address z.z.z.z y.y.y.y

ip address x.x.x.x w.w.w.w secondary

z.z.z.z = ip address **primary**

y.y.y.y = mask for primary IP address

x.x.x.x = ip address **secondary**

w.w.w.w = mask for secondary IP address

HTH.

Hall of Fame Super Gold

Re: How to assign 3 IP address to port?

Actually you can have as many secondary addresses you like on a single interface.

Re: How to assign 3 IP address to port?

Yes, possible...

but what is the sense?

Hall of Fame Super Gold

Re: How to assign 3 IP address to port?

Many people make migrations, changes, and expansions, but use addresses that in their view cannot be changed (need to re-configure servers and PCs that really cannot be touched), so having multiple addresses is a often a real necessity.

Re: How to assign 3 IP address to port?

In that case - surely it would make sense, with a layer 2 infrastrcuture with more than 1 flat VLAN - to run multiple layer 3 interfaces, rather than sedonary IP's???

Hall of Fame Super Gold

Re: How to assign 3 IP address to port?

Believe it or not, a lot of people is uncomfortable with, or do not have the equipment for VLANs.

Beside, often they want multiple addresses in the same subnet.

Luckily the router has no problem in doing so.

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