07-14-2008 02:23 AM - edited 03-03-2019 10:42 PM
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?
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07-14-2008 02:35 AM
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.
07-14-2008 02:29 AM
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.
07-14-2008 02:30 AM
I don't think I need subinterfaces. Just want 3 IP address. 1 Primary and 2 Secondary. How do I configure that?
07-14-2008 02:35 AM
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.
07-14-2008 02:44 AM
Actually you can have as many secondary addresses you like on a single interface.
07-14-2008 02:46 AM
Yes, possible...
but what is the sense?
07-14-2008 02:52 AM
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.
07-14-2008 02:56 AM
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???
07-14-2008 03:00 AM
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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