Hello Don, I think you could set up DHCP scopes on a server and use the "ip helper address" command to direct dhcp discover broadcasts from your clients. The router should place its own sub-interface address in the packet and send it to the DHCP server. The server should then pick from the corresponding scope depending on the router IP address. I know of at least one server which does that but I do not want to mention it here.
Winston V. Shaw CCIE(#7991) -----Original Message----- From: Don Pezet [mailto:[EMAIL PROTECTED]] Sent: Monday, July 22, 2002 1:15 PM To: [EMAIL PROTECTED] Subject: DHCP Server on Multiple VLANs [7:49403] Hey guys, I have a Cisco 3620 connected to a 2948G-L3 which in turn provides layer three services to a cluster of 3548XLs. I have 9 operating VLANs and have been trying to work out a scenario for DHCP in my environment. Right now, we assign static IPs in all 9 vlans because we do not want to provide seperate DHCP servers for each. If we could find a way to get one server to provide DHCP to all the VLANs then we could implement it. The trick is, each VLAN is a different subnet. I had heard that if you use the 3620 as a DHCP server, create subinterfaces on a FE port using ISL and assign IP addresses appropriately, and create multiple DHCP pools, then the router would issues IPs from pools that matched the interface it drew the request from. However, when I try this it just issues IPs from the first pool until it is full and then moves to the next. Is there a way to make sure the router assigns correct IPs on the correct sub-interfaces? Is there a 3rd party DHCP server that would do this better? Let me do a sample config to show what I tried. Each network has a network printer at .200 (don't ask) and a router sub-interface at .1 except the 10.10.10.0 network which has reserved IPs through 100, but still a router interface at .1 Here's the Cisco 3620 DHCP portion of the config: ! ip dhcp excluded-address 10.10.10.1 10.10.10.100 ip dhcp excluded-address 192.168.1.1 ip dhcp excluded-address 192.168.1.200 ip dhcp excluded-address 192.168.2.1 ip dhcp excluded-address 192.168.2.200 ip dhcp excluded-address 192.168.3.1 ip dhcp excluded-address 192.168.3.200 ip dhcp excluded-address 192.168.4.1 ip dhcp excluded-address 192.168.4.200 ip dhcp excluded-address 192.168.5.1 ip dhcp excluded-address 192.168.5.200 ip dhcp excluded-address 192.168.6.1 ip dhcp excluded-address 192.168.6.200 ip dhcp excluded-address 192.168.7.1 ip dhcp excluded-address 192.168.7.200 ip dhcp excluded-address 192.168.8.1 ip dhcp excluded-address 192.168.8.200 ! ip dhcp pool Vlan1 network 10.10.10.0 /24 dns-server 4.2.2.1 default-router 10.10.10.1 ! ip dhcp pool Vlan10 network 192.168.1.0 /24 dns-server 4.2.2.1 default-router 192.168.1.1 ! ip dhcp pool Vlan20 network 192.168.2.0 /24 dns-server 4.2.2.1 default-router 192.168.2.1 ! ip dhcp pool Vlan30 network 192.168.3.0 /24 dns-server 4.2.2.1 default-router 192.168.3.1 ! ip dhcp pool Vlan40 network 192.168.4.0 /24 dns-server 4.2.2.1 default-router 192.168.4.1 ! ip dhcp pool Vlan50 network 192.168.5.0 /24 dns-server 4.2.2.1 default-router 192.168.5.1 ! ip dhcp pool Vlan60 network 192.168.6.0 /24 dns-server 4.2.2.1 default-router 192.168.6.1 ! ip dhcp pool Vlan70 network 192.168.7.0 /24 dns-server 4.2.2.1 default-router 192.168.7.1 ! ip dhcp pool Vlan80 network 192.168.8.0 /24 dns-server 4.2.2.1 default-router 192.168.8.1 ! interface FastEthernet1/0 description connected to Private Network no ip address duplex auto speed auto ! interface FastEthernet1/0.1 encapsulation isl 1 ip address 10.10.10.1 255.255.255.0 no ip redirects ! interface FastEthernet1/0.10 encapsulation isl 10 ip address 192.168.1.1 255.255.255.0 no ip redirects ! interface FastEthernet1/0.20 encapsulation isl 20 ip address 192.168.2.1 255.255.255.0 no ip redirects ! interface FastEthernet1/0.30 encapsulation isl 30 ip address 192.168.3.1 255.255.255.0 no ip redirects ! interface FastEthernet1/0.40 encapsulation isl 40 ip address 192.168.4.1 255.255.255.0 no ip redirects ! interface FastEthernet1/0.50 encapsulation isl 50 ip address 192.168.5.1 255.255.255.0 no ip redirects ! interface FastEthernet1/0.60 encapsulation isl 60 ip address 192.168.6.1 255.255.255.0 no ip redirects ! interface FastEthernet1/0.70 encapsulation isl 70 ip address 192.168.7.1 255.255.255.0 no ip redirects ! interface FastEthernet1/0.80 encapsulation isl 80 ip address 192.168.8.1 255.255.255.0 no ip redirects ! Thanks, Don Pezet [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=49484&t=49403 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
