Dear all,
Real funny one I'm hoping one of you clever guys can help me understand....
I have a bit of a hybrid setup.. with a cisco SG350 connected to an old Dell 6224 with a set of servers connected to both switches.
The cisco is connected to the dell via trunk port and it trunks vlans 10,101-103,190,200,254,2000,2122,2126
The old DHCP server (192.168.10.10) sits on the old servers connected to the Dell switches.
The new DHCP server (192.168.10.12) sits on the new servers and is connected to the Cisco switch
All users are connected to VLAN 200 who's interface has an IP address of 192.168.200.253 on the new switch.
It's 192.168.200.254 on the old switch.
VLAN 190 has an IP address of 192.168.100.254 on the old Dell switch and 192.168.100.253 on the new cisco switch.
All users connect to the new cisco switch.
I added ip dhcp relay address 192.168.10.10 & ip dhcp relay address 192.168.10.12 to the Cisco switch (and it already exists on the Dell switch)
I added the dhcp scopes 192.168.100.0 & 192.168.200.0 to the new DHCP server activated them and deactivated them on the old server.
I tested it on a test PC and all seemed fine yesterday with the PC getting a 192.168.200.nn address and the DHCP server listed as 192.168.10.12. I then removed the ip dhcp relay address 192.168.10.10 from the Cisco, happy days or so I thought.
I came in this morning to discover that a bunch of people who had turned off their PC's last night, were now getting 192.168.100.nn IP addresses not 200.nn as should have been the case.
I disabled the scopes on the new DHCP server and re-enabled them on the old DHCP server and after a reboot people are able to get a 200.nn Ip address again.
So in trying to troubleshoot this my questions are;
1. It appears that the ip dhcp relay address command isnt doing a whole lot since I've not readded it to the cisco switch and people are still able to get their DHCP requests to the old server on the old switch, how is that possible?
2. Why would people get an IP address for a scope that's not aligned to the IP address of the VLAN that they're in... I thought the source requesting address would be 192.168.200.253 (the new cisco) and as a result a 192.168.200.nn address would be returned, not a 192.168.100.nn
I appreciate you might need more detail.... but that's my first stab.
kind regards,
Paul.
