I have a cisco 3560 24PS and its connected to two ADSL broard band routers.
one is a personal broadband line using a Billion ADSL broadband router, and the other is a business broardband line using BT's 2wire broadband line.
on the Billion routers i have various things attached like a NAS and a printers, both wired connections. then i have laptops and phones that connect over wifi, so its configured to act as a DHCP server
the only thing conncted to my 2wire router is my company's laptop (wired or wifi depending on where i'm working from), so again i have it working as a dhcp server.
The switch is configured with multiple vlans, with dhcp scopes assigned for each vlan.
I have a static route pointing all traffic to my Billion ADSL for internet connectivity.
The problem i'm having is that when i turn on the cisco switch, all wifi conected devices loose their conection.
only 2 things get it working again, a reboot of the router, or disabling then enabling the DHCP service on the router.
upon further analysis i was able to find out that the devices were not able to pick up an address from the router.
again i looked deeper into this and i can see the following on logs of my router:
Jul 24 09:32:34 DHCP SERVER: DHCP ack to 7c:61:93:30:79:29
Jul 24 11:53:31 DHCP SERVER: DHCPINFORM from 192.168.1.9
Jul 24 11:53:46 DHCP SERVER: DHCPINFORM from 192.168.1.9
Jul 24 11:54:01 DHCP SERVER: DHCPDISCOVER from 00:11:bb:b7:fe:00 via 192.168.1.9
Jul 24 11:54:02 DHCP SERVER: DHCP offer to 00:11:bb:b7:fe:00
Jul 24 11:54:02 DHCP SERVER: Exiting as another DHCP server is found
so it seems that the router tuns off its DHCP capabilities because it detects that my Cisco switch is running DHCP services.
I'm at a loss here. I need to figure out how to keep the billion routers DHCP running when ever the switch is turned on.
can someone help out here? is there a way of filtering out any DHCP chat from the switch to the router?
according to rfc 2131 the DHCP INFORM message is from a client(having already an ip address configured by other means) to a server for requesting options. and the DHCP DISCOVER confirms this is considered a client but it shouldn't be
I'm gonna take a closer look at your config and post your topology also.
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