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Cat 3550 FastEthernet port IP assignment

Is there a way to insure that each port on a 3550 will only allow DHCP to issue one pre-determined IP address? I will not know the MAC addresses in advance either. The 3550 is in a student housing building. The students are only here for a short amount of time. I want to match IP addresses with room numbers, so I can cross-reference that information later if needed. Thanks.


Re: Cat 3550 FastEthernet port IP assignment

One thing you can do is make each port a router port by issuing the command "no switchport" in the interface configuration of each port. Assign a /30 address space to each port, with one host address assigned to the port itself and the other to the DHCP scope for that port's subnet. The caveats here are that this will eat into your IP address space quicker than you may have anticipated, and that having so many router ports may be too much of a burden for the 3550's CPU.

I was looking in the 3550 documentation and came across something called DHCP option 82. This seems to be a way of tracking a DHCP-assigned IP address by port. I didn't read it for the full details, but it may be a more efficient way for you to track an address to a port than what I described above. Here is the link:

Good Luck.


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