01-30-2020 08:54 AM - edited 01-30-2020 09:01 AM
I have a very simple setup. A Netgear router that is connected to WAN and has four ports. If I connect a PC to any port, I get an IP from DHCP (192.168.10.0/24) and the internet is also working.
What I want to do is to extend this to a Cisco switch. On the switch, I have created VLAN 10 and assigned the ports 1-10 to that VLAN. Port 1 is connected to the Netgear as a WAN/DHCP. Now if I connect a PC to any of the remaining ports, I can't get an IP from the Netgear's DHCP server. What am I doing wrong?
int fastEthernet1/0/1 switchport access vlan 10 description NETGEAR int fastEthernet1/0/2 switchport access vlan 10 description ConnectedToPC int fastEthernet1/0/3 switchport access vlan 10 int fastEthernet1/0/4 switchport access vlan 10 int fastEthernet1/0/5 switchport access vlan 10 int fastEthernet1/0/6 switchport access vlan 10
If I connect a PC to port 2 and another to port 3; and give them an IP in the same subnet, I can ping them. But the DHCP is the issue.
01-30-2020 09:05 AM
- Should work at first glance, is there anything in the logs (of the switch and or the DHCP server) ; when you force the PC to get a new IP with (ipconfig /release and renew) for instance. It's best to test this explicit in order to not confuse with machines having an IP already.
M.
01-30-2020 11:12 AM
Hello,
Try adding "spanning-tree portfast" to the access ports. Without it DHCP requests don't get forwarded while spanning tree is being negotiated when the ports come up.
Hope this helps
02-09-2020 03:47 AM
I added spanning tree to both ports but it's still the same. There is a trunk on the switch. Could it be causing any issues?
02-09-2020 04:32 AM
Hello
First of all you may require a crossover cable between the the switch and the negear router/siwtch if the ports are not mdix compatible.
Second put all access ports on the new switch in access vlan 1 test again
switch
interface x/x
switchport host
switchport access vlan 1
02-10-2020 07:23 AM
You might need DHCP snoop turned on. The multicast/broadcast for DHCP discovery might be not getting to the server.
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