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VLAN stuck or DHCP is fragged?

    Let me set the scenario:

PC1 is attached to access swtich on port 1/0/8. Port 1/0/8 was originally switchport access vlan 10.

Access switch is connected to Distro 1. SVI VLAN 10 is correctly setup:

description USERS_GROUP10

ip address 10.10.10.1 255.255.255.0

ip helper-address 192.168.129.148

no ip redirects

ip pim sparse-mode

ip igmp query-interval 125

The last 4 of mac address of PC1 is abcd. The mac address is seen on port 1/0/8 on the access switch (using port-security sticky).

The mac address is seen in the mac-address table on the distro.

It's getting an IP of 10.10.10.75 (which is the VLAN10 scope on the MS DHCP server)

Note that most other devices have been working fine. These PC's had been WinXP OS's, but they were just reimaged to be Win7. We confirmed that the PC's NIC is set up for DHCP automatic.

Now...

We ended up moving the PC1 to a different vlan. Same port. We reset the port and put it as switchport access vlan 20.

On the distro switch,, SVI vlan 20 is set up as above, except ip address 10.10.20.1 255.255.255.0...everything else is the same.

There are plenty of IP addresses in the DHCP vlan 20 scope. The MAC address of PC1 is seen on the port in the mac address table. It's showing connected as status. The mac address is seen in the mac address table on the distro switch.

However, the distro swtich is not resolving an IP address to the mac address in the arp table. We've tried clearing the arp cache, restarting the distro switch, and even restarting the DHCP server. Even though the PC is in vlan 20, it's still trying to get an IP address from vlan 10. We confirmed that the IP address on the PC is NOT statically assigned. There are no reservations on the DHCP server, nor exclusions. We put the PC back into vlan 10, and it now has connectivity.

We cannot figure out WHY it keeps getting the .10.xxx ip addresses. The vlan's ip addresses are within the EIGRP routing table. It's just several computers that are having this issue. Our server team is saying it's our issue; we are saying it's a DHCP issue.  Any thoughts?

1 REPLY
Green

VLAN stuck or DHCP is fragged?

Norm,

Just a hunch.

Are your dhcp scopes set up as a superscope on your MS dhcp server ?

Regards,
Alex.
Please rate useful posts.

Regards, Alex. Please rate useful posts.
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