A feature invaluable to any ISP would be DHCP Snooping with option 82 as found in Cisco and AliedTelesyn products :

http://www.cisco.com/en/US/products/hw/ ... 35791.html

http://www.alliedtelesis.com/datasheets ... on%2082%22

How to implement and use this option in the MT DHCP-Server?

I think i am having some like Dynamic ARP Inspection or DHCP Snooping...

In the Log i can see a lot of ip assignment and deassignment from the same MAC in any seconds and all theses IPs are stay in "busy" status in the leases table.

I need to constantly check the leases table and the Log and do a rule in the bridge filter dropping the access of the MAC.

Have someone this problem?

Thanks and regards!

I have some problem

"ip assigned", after 0,5 second - "ip deassigned" - but in DHCP-SERVER Lease status "busy"

sorry my english so bad.

--------------------
Mikrotik RouterOS v.3.13, Pentum 4 1,8 Ghz, Cpu Load 48%

4 - Vlan, 1 - DHCP-Server per Vlan, Abonents over 250

'busy' means there are already this address in the network, and it cannot be assigned second time at least until the first computer is off =)

I know. But in this case involved only one computer. Look carefully at the time

24/08/2008 19:00:00 | dhcp info debug | server-24 assigned 172.31.4.20 to 00:0E:2E:6C:00:00 -> authorized,tested,bound
24/08/2008 19:00:01 | dhcp info debug | server-24 deassigned 172.31.4.20 from 00:0E:2E:6C:00:00 -> busy
24/08/2008 19:00:03 | dhcp info debug | server-24 to 00:0E:2E:6C:00:00 172.31.4.20 address alredy in use

took only three seconds
-----------------------------------
server:
Pentium 4 1700MHz
Mikrotik RouterOS 3.13
License Level 4
Network interface 2
- on Uplink
- on with 4 vlan and 1 dhcp server per vlan

----------------------------------
My DHCP SERVER parametrs
----------------------------------
Name: server-24
Interface: vlan24
Lease Time: 01:00:00
Authoritative: after 2s delay
Bootp Support: Off
Add ARP For Leases: On
Always Broadcast: Off
Use RADIUS : On
----------------------------------
Server-24 work with networks:
172.31.4.0/27
172.31.4.32/27
172.31.4.64/27
172.31.4.96/27
172.31.4.128/27
172.31.4.160/27
172.31.4.192/27
172.31.4.224/27
172.31.5.0/27
172.31.5.32/27
172.31.5.64/27
172.31.5.96/27
172.31.5.128/27
172.31.5.160/27
172.31.5.192/27
172.31.5.224/27
-------------------------------------
Strangely but the problem only in one range addresses 172.31.4.* (in particular addresses - 172.31.4.20, 172.31.4.6, 172.31.4.111, 172.31.4.112, 172.31.4.113, the rest are working normally), all computers in other range 172.31.5.* - work fine.

And yet. The client has two computer, one with ip - 172.31.4.20 ,and with ip 172.31.5.2. At first there was the problem at the second no. If you manually swap MAC-addresses or network card, problem remains, but now at the second computer. So the problem is not in the client computer.

172.31.4.* - Dead Zone?
There are thoughts?

Sorry for my English is not my native language.