Issue with VLAN not receiving DHCP on PC55xx Stack in second building

Question

I'm trying to get a DHCP assigned IP address from our WatchGuard firewall cluster network 4 to a device connected in our 2nd building.  The network consists of 2 PowerConnect 55xx stacks connected with fiber SFP's on 1/te1/0/2 and 2/te2/0/2.  The original fiber connection on 1/te1/0/2 has been working fine.  We just added the second fiber connection (2/te2/0/2) to segregate our service network and provide wireless access to the second building. Scenario:Firewall consisting of 2 WatchGuard M300's in a FireCluster Network 1 on the cluster is Private (DHCP Disabled)Network 2 on the cluster is Public (DHCP Disabled)Network 3 on the cluster is Test (DHCP Enabled)Network 4 on the cluster is Service (DHCP Enabled) Building 1 Stack consisting of 5 Dell PowerConnect 55xx switches VLAN 1 is Private with all ports except as otherwise noted and 2/te2/0/2 (tagged) as members.VLAN 2 is Public and ports 1/gi1/0/1 to 1/gi1/0/8 and 2/te2/0/2 (tagged) as members.VLAN 3 is Test and ports 1/gi1/0/9 to 1/gi1/0/12 and 2/te2/0/2 (tagged) as members.VLAN 4 is Service and ports 1/gi1/0/13 to 1/gi1/0/22 and 2/te2/0/2 (untagged) as members. 1/te1/0/2 is configured as Layer2 in Access mode and only VLAN1.2/te2/0/2 is configured as Layer2 in Trunk mode with the Native VLAN ID set to 4. Building 2 Stack consisting of 2 Dell PowerConnect 55xx switches VLAN 1 is Private with all ports except as otherwise noted and 2/te2/0/2 (tagged) as members.VLAN 2 is Public and port 2/te2/0/2 (tagged) as the only member.VLAN 3 is Test and port 2/te2/0/2 (tagged) as the only member.VLAN 4 is Service and ports 2/gi2/0/45 to 2/gi2/0/48 and 2/te2/0/2 (untagged) as members. 1/te1/0/2 is configured as Layer2 in Access mode and only VLAN1.2/te2/0/2 is configured as Layer2 in Trunk mode with the Native VLAN ID set to 4. 2/gi2/0/45 to 2/gi2/0/48 are configured as Layer2 in General mode with VLAN 4 untagged. Devices on VLAN 4 in Building 1 are receiving an IP address but devices in Building 2 are not.  I'm looking for suggestions on how we can get the DHCP assignments to pass through.Respectfully,Devrin

DevrinK · Accepted Answer

On the expert advise of Daniel below is what was implemented to resolve the issue.

LAG1 was configured in trunk mode and then ports te1/0/2 and te2/0/2 were added to LAG1 with LACP on both switch stacks. Since trunk mode carries all VLAN traffic this resolved the issue with receiving a DHCP address on the endpoint and by configuring the LAG we essentially doubled the bandwidth of the connection between the buildings.

DevrinK · Answer

Thanks for the reply Daniel.

Spanning tree is set to RSTP (default) on both stacks.

We did attempt a static IP on a laptop connected to port gi2/0/45 on building 2's stack and couldn't ping the gateway IP on the firewall. The same laptop did receive a DHCP assigned IP from our server when connected to port gi2/0/1 (VLAN 1) . The RSTP state of port te2/0/2 in building 2's stack is blocking and STP has it discarding/alternate. Would configuring MSTP and assigning VLAN 4 an MSTP instance resolve this?

Regards,

Devrin

Networking General

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