DHCP problem L3 switch with vlans

120 pts.
Tags:
DHCP
Networking
Switches
Virtualization
VLAN
Hi, I have searched this forum and found a lot of help regarding this problem. I have 3 Vlans configured on my Dell PowerConnect 6224 (L3 Switch) and a DHCP server Windows Server 2000 with different subnet scopes, as far as I know I need to set-up a bootdhcprelay server and enable bootdhcprelay which I have done, but when I try to get a dhcp address from my client pc I don't get an address. When I configure the client with a manual IP it communicates as expected.
Here is my running-config, is there anything wrong?

!Current Configuration: !System Description "Dell 24 Port Gigabit Ethernet, 2.0.0.12, VxWorks5.5.1" !System Software Version 2.0.0.12 !configure vlan database vlan 10,20,30,40 vlan association subnet 10.10.1.0 255.255.255.0 1 vlan association subnet 10.10.10.0 255.255.255.0 10 vlan association subnet 10.10.20.0 255.255.255.0 20 vlan association subnet 10.10.30.0 255.255.255.0 30 vlan association subnet 10.10.40.0 255.255.255.0 40 exit hostname "L3_Switch" stackmember 1 1 exit switch 1 priority 1 ip address 10.10.1.1 255.255.255.0 ip default-gateway 10.10.10.2 ip domain-name XXXX ip name-server 10.10.10.10 ip routing ip route 0.0.0.0 0.0.0.0 10.10.10.2 bootpdhcprelay enable bootpdhcprelay serverip 10.10.10.10 ip helper-address 10.10.10.1 10.10.10.10 37 ip helper-address 10.10.10.1 10.10.10.10 49 ip helper-address 10.10.10.1 10.10.10.10 137 ip helper-address 10.10.10.1 10.10.10.10 138 ip helper-address 10.10.10.10 255.255.255.0 37 ip helper-address 10.10.10.10 255.255.255.0 42 ip helper-address 10.10.10.10 255.255.255.0 49 ip helper-address 10.10.10.10 255.255.255.0 53 ip helper-address 10.10.10.10 255.255.255.0 137 ip helper-address 10.10.10.10 255.255.255.0 138 ip helper-address 10.10.20.1 10.10.10.10 37 ip helper-address 10.10.20.1 10.10.10.10 49 ip helper-address 10.10.20.1 10.10.10.10 137 ip helper-address 10.10.20.1 10.10.10.10 138 ip helper-address 10.10.30.1 10.10.10.10 37 ip helper-address 10.10.30.1 10.10.10.10 49 ip helper-address 10.10.30.1 10.10.10.10 137 ip helper-address 10.10.30.1 10.10.10.10 138 ip helper-address 10.10.40.1 10.10.10.10 37 ip helper-address 10.10.40.1 10.10.10.10 49 ip helper-address 10.10.40.1 10.10.10.10 137 ip helper-address 10.10.40.1 10.10.10.10 138 interface vlan 10 name "Main_Production" routing ip address 10.10.10.1 255.255.255.0 exit interface vlan 20 name "Vlan_2" routing ip address 10.10.20.1 255.255.255.0 exit interface vlan 30 name "Vlan_3" routing ip address 10.10.30.1 255.255.255.0 exit interface vlan 40 name "Vlan_4" routing ip address 10.10.40.1 255.255.255.0 exit username "admin" password 4f70cfb1451a1b0ce0b872421bee6c1c level 15 encrypted ip dhcp filtering ! interface ethernet 1/g1 switchport mode general switchport general pvid 10 no switchport general acceptable-frame-type tagged-only switchport general allowed vlan add 10,20,30,40 exit ! interface ethernet 1/g2 switchport mode general switchport general pvid 20 no switchport general acceptable-frame-type tagged-only switchport general allowed vlan add 10,20 exit interface ethernet 1/g3 switchport mode general switchport general pvid 30 no switchport general acceptable-frame-type tagged-only switchport general allowed vlan add 30 exit ! interface ethernet 1/g24 switchport mode general switchport general pvid 10 no switchport general acceptable-frame-type tagged-only switchport general allowed vlan add 10,20,30,40 exit exit

Please tell me if you can see any errors.
ASKED: February 28, 2008  12:50 PM
UPDATED: April 13, 2014  11:44 PM

Answer Wiki

Thanks. We'll let you know when a new response is added.

Looks like you have IP Helper addresses setup for a number of services, but not for DHCP and/or bootp. The service numbers for common forwarders are:

Time 37
TACACS 49
DNS 53
BOOTP/DHCP Server 67
TFTP 69
NetBIOS name service 137
NetBIOS datagram service 138

Notice that you don’t have one configured for DHCP. Also, you don’t have a IP forwarder setup to forward these protocols, it’s likely you will need that as well.

http://www.ciscopress.com/articles/article.asp?p=330807&seqNum=9″>Here
is a good article that should get you going. Pay close attention to “Example 2-6 Verifying IP Helper Address Configuration” in this article.

This should get you going.

Discuss This Question: 8  Replies

 
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  • Michi
    Thanks for your reply I just tried adding the port for BOOTP/DHCP Server 67 but for some reason the Dell switch tells me that DHCP/BOOTP packets are handled in DHCP relay, it won't let me add that port! Here is what I entered: helper-address 10.10.10.10 67 this is what I get DHCP/BOOTP packets are handled in DHCP relay Thanks for any more help
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  • Jerry Lees
    Whoops. Sorry about that... when I looked at the question and I read DELL --- then say the commands and saw CISCO IOS. What is the output of the "show bootpdhcprelay" command? Specifically, how many jops away is your dhcp server? Here is a DELL ARTICLE that goes over these commands.
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  • Michi
    The output I get is: Maximum Hop Count....................4 Minimum Wait Time(Seconds)...0 Admin Mode....................................Enable Server IP Address..........................10.10.10.10 Circuit Id and remote Agend ID Option Mode.....Disable Request Received.........................800 Requests Relayed........................800 Packets Discarded.......................800 My DHCP Server is connected straight to the switch on port 1/g1 Thanks for your help so far
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  • Jerry Lees
    Looks like the relay is infact working-- it's just discarding all of them. Back to basics questions, so I'm sure I'm not missing anything. It's looking like the switch is either not knowing what to with the packets or where to send them, since it is discarding all of them. Can you get IP addresses from DHCP for clients that are on the same subnet/vlan as the DHCP Server and that works properly? (I'm assuming you have a switch downstream from port 1 here that you can use to test) Can you get an IP address from a system plugged into port 24 (since it is on vlan 10 as well)? If the DHCP Server is in an AD environement, has it been authorized and are all the scopes turned on? It also looks like you've got 5 VLAN's setup (this one is missing "vlan association subnet 10.10.1.0 255.255.255.0 1" everywhere but where it's associated): Vlan 10 = "Main Prod" = 10.10.10/24 IP= 10.10.10.1 Int= 1/g1 + 1/g24 Vlan 20 = "VLAN_2" = 10.10.20/24 IP= 10.10.20.1 int = 1/g2 + 1/g24 Vlan 30 = "VLAN_3" = 10.10.30/24 IP= 10.10.30.1 int = 1/g3 + 1/g24 Vlan 40 = "VLAN_4" = 10.10.40/24 IP= 10.10.40.1 int = ???? + 1/g24 Vlan 1 = ???? = 10.10.1/24 IP = 10.10.1.1 Notice that you don't have vlan 1 assigned to any interfaces (or defined) and VLAN_4 is defined but not assigned to interfaces other than port 24. (Looks like you intend port 24 to be a sniffer port, correct?) You might look this document over on vlan configuration and see if it's helpful. You might post a routing table, since DHCP Relay turns DHCP broadcasts into directed packets. Can the switch itself ping all the hosts (other than the ones defined to it's own interfaces) and subnets involved when you telnet/ssh/console to it?
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  • Jerry Lees
    michi, did this last posting help you out at all?
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  • Michi
    Sorry, I can't get an IP address from port 24, I have no added vlan1 association subnet 10.10.1.0, still nothing. Have you got any more ideas? Thanks
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  • Jerry Lees
    Whew! I'm getting fresh out of ideas. It does sound like we are missing something in the DHCP relay settings. Can you get an IP on the segment that the DHCP server is plugged into?
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  • Jwest023
    I see that you have dhcp filtering turned on, you need to disable that.
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