topic Re: 1x DHCP Server 2019 - multiple VLANs - what am I doing wrong? in ExtremeSwitching (EXOS/Switch Engine)

1x DHCP Server 2019 - multiple VLANs - what am I doing wrong?

frankygth — Tue, 06 Oct 2020 13:20:55 GMT

I’m having an Extreme Networks x460 Switch and 2 VLANs. On VLAN 11 there’s a Windows Server 2019 located which has 2 scopes (for the different vlans)

VLAN 11 IP Switch: 192.168.11.253/24
IP DHCP Server: 192.168.11.1

VLAN 193 IP Switch: 192.168.193.253/24

I’m able to ping the DCHP Server from the Switch

I did a config bootprelay add 192.168.11.1 vr VR-Default
Also enable bootprelay VLAN VLAN11
and enable bootprelay VLAN VLAN193

and last but not least: enable ipforwarding vlan11
and enable ipforwarding vlan193

When I connect a client to VLAN 193 I’m not getting an IP Adress.

The DHCP Server has a Scope for: 192.168.11.100-110 and a Scope for: 192.168.193.100-110

Re: 1x DHCP Server 2019 - multiple VLANs - what am I doing wrong?

frankygth — Tue, 06 Oct 2020 13:24:19 GMT

rtlookup:

#d 192.168.11.0/24 192.168.11.253 1 U------um--f- Verwaltung-11 0d:0h:28m:14s

sh config nettools:

# Module netTools configuration.
#
enable dhcp vlan Default
enable dhcp vlan Mgmt
configure bootprelay add 192.168.11.1 vr VR-Default
enable bootprelay ipv4 vlan Default
enable bootprelay ipv4 vlan Client-193
enable bootprelay ipv4 vlan Verwaltung-11

Re: 1x DHCP Server 2019 - multiple VLANs - what am I doing wrong?

BradP — Tue, 06 Oct 2020 13:24:55 GMT

hi Frankygth
First thing I would do is get a packet capture on the server and see if the Discover is coming in and the Offer is going out.

Brad

Re: 1x DHCP Server 2019 - multiple VLANs - what am I doing wrong?

frankygth — Tue, 06 Oct 2020 13:27:21 GMT

EXOS-VM.23 # sh iproute
Ori Destination Gateway Mtr Flags VLAN Duration
#d 192.168.11.0/24 192.168.11.253 1 U------um--f- Verwaltung-11 0d:0h:31m:25s
#d 192.168.193.0/24 192.168.193.253 1 U------um--f- Client-193 0d:0h:31m:25s

Re: 1x DHCP Server 2019 - multiple VLANs - what am I doing wrong?

frankygth — Tue, 06 Oct 2020 13:30:23 GMT

sh vlan
Untagged ports auto-move: Inform
-----------------------------------------------------------------------------------------------
Name VID Protocol Addr Flags Proto Ports Virtual
Active router
/Total
-----------------------------------------------------------------------------------------------
Client-193 193 192.168.193.253/24 -f------------------------ ANY 1 /6 VR-Default
Default 1 ---------------------------------------------- ANY 0 /0 VR-Default
Mgmt 4095 ---------------------------------------------- ANY 0 /1 VR-Mgmt
Verwaltung-11 11 192.168.11.253 /24 -f------------------------ ANY 1 /6 VR-Default

Re: 1x DHCP Server 2019 - multiple VLANs - what am I doing wrong?

frankygth — Tue, 06 Oct 2020 13:34:42 GMT

EXOS-VM.34 # sh bootprelay
Bootprelay : Disabled on virtual router "VR-Default", but enabled on some VLANs
Include Secondary : Disabled
DHCP Relay Agent Information Option : Disabled on virtual router "VR-Default"

Bootprelay servers for virtual router "VR-Default":
Destination: 192.168.11.1

DHCP/BOOTP relay statistics for virtual router "VR-Default"
Received from client = 4 Received from server = 0
Requests relayed = 4 Responses relayed = 0
DHCP Discover = 4 DHCP Offer = 0
DHCP Request = 0 DHCP Ack = 0
DHCP Decline = 0 DHCP NAck = 0
DHCP Release = 0
DHCP Inform = 0

I think the Client is asking for DHCP but I’m not sure if the switch itself drops the packet. To me it seams as if the switch is not going to forward the offer to the DHCP server? What do you think?

Re: 1x DHCP Server 2019 - multiple VLANs - what am I doing wrong?

frankygth — Tue, 06 Oct 2020 13:35:40 GMT

I’m wondering if: DHCP Relay Agent Information Option : Disabled on virtual router "VR-Default" this could be the Problem?

Re: 1x DHCP Server 2019 - multiple VLANs - what am I doing wrong?

frankygth — Tue, 06 Oct 2020 13:37:16 GMT

but I did a conf bootprelay add 192.168.11.1 vr VR-Default. Is there anything else I need to do to get the relay working?

Re: 1x DHCP Server 2019 - multiple VLANs - what am I doing wrong?

Stefan_K_ — Tue, 06 Oct 2020 14:11:13 GMT

Servus Frank,

in the “show bootprelay” output we can see that the switch relays the DHCP-Discover. The question is where the packet is going and why it doesn’t come back. 🙂

Easiest thing would be to start a wireshark on the windows server and look if the packets are received from the server. The problem could be anything (DHCP-Scope problem, routing problem, static route on the DHCP-Server and so on...)

Best regards
Stefan

Re: 1x DHCP Server 2019 - multiple VLANs - what am I doing wrong?

frankygth — Tue, 06 Oct 2020 14:19:33 GMT

Hi Stefan,

was mich wundert ist: DHCP Relay Agent Information Option: Disabled on virtual Router VR-Default

Ich werde mal Wireshark aktivieren und schauen, ob am Server was ankommt.

lg,

Frank

Re: 1x DHCP Server 2019 - multiple VLANs - what am I doing wrong?

frankygth — Tue, 06 Oct 2020 14:47:10 GMT

ok, it seems like, the offer is not getting back. I see a DHCP Discover from 192.168.198.253 to 192.168.11.1 and afterwards I see the DHCP Offer from 192.168.11.1 to 192.168.193.253.
and nothing more… Filter in Wireshark is DHCP

Re: 1x DHCP Server 2019 - multiple VLANs - what am I doing wrong?

frankygth — Tue, 06 Oct 2020 14:54:02 GMT

so the offer can’t reach 192.168.193.253 - ipforwarding is enabled von both vlan. Do I need anything else? like a iproute

Re: 1x DHCP Server 2019 - multiple VLANs - what am I doing wrong?

frankygth — Tue, 06 Oct 2020 15:15:06 GMT

I found the error and it’s working now - thank you!!
The problem was the getting back to the VLAN . The Problem was more firewall related then switch related. Best Regards, Frank PS: Wireshark did the trick

Re: 1x DHCP Server 2019 - multiple VLANs - what am I doing wrong?

DeVoID — Tue, 06 Oct 2020 21:34:03 GMT

Silly question, but you have built the VLANS in your router right?

Re: 1x DHCP Server 2019 - multiple VLANs - what am I doing wrong?

DeVoID — Tue, 06 Oct 2020 21:34:23 GMT

Never mind, i see you have resolved the issue.

Re: 1x DHCP Server 2019 - multiple VLANs - what am I doing wrong?

frankygth — Thu, 08 Oct 2020 14:14:27 GMT

Yes, I did that, but I did it within GNS3 (for testing purposes). The Problem was, that the offer didn’t get back in the VLAN. I did see the Request in Wireshark also the offer but there was no Ack. So I had to fix the Firewall / VLAN Issue and everything worked then. I was just confused, if the config on the Switch was ok, which ist was 😉

Thank You very much..