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So my switch has Cumulus Linux running on it and I have ESXi running in my network.

So my main network is on 172.22.0.0/24 which has my my esxi. The networks I want esxi vms to run on is 172.22.20.0/24 172.22.10.0/24. So the .20 serves dhcp fine and I have no issues with it. The issue comes with the .10 and I am not sure why its failing since I have the same configurations for .20.

This is what I get from syslog when I run it on the switch and try to connect a vm on the network to it.

Mar 11 08:14:08 cumulus dhcpd: DHCPDISCOVER from 00:50:56:80:4d:b8 
(gitlabs) via vlan10-InfaNet
Mar 11 08:14:08 cumulus dhcpd: DHCPOFFER on 172.22.10.100 to 00:50:56:80:4d:b8 (gitlabs) via vlan10-InfaNet
Mar 11 08:14:08 cumulus dhcpd: send_packet: No such device

When I run a dhcpdump i get this

sudo dhcpdump -i vlan10-InfaNet
Ignored non IPv4 packet: 2048
Ignored non IPv4 packet: 2048

On every DHCP offer the get the ignored non ipv4 thing and I am not sure why. When I statically assign an ip to a vm it works fine so I don't think it networking configurations but I might be wrong.

/etc/default/isc-dhcp-server

INTERFACES="br-main vlan20-VMNet vlan10-InfaNet"

/etc/dhcp/dhcpd.conf

# vlan 20 VMNet
subnet 172.22.20.0 netmask 255.255.255.0 {
  option routers 172.22.20.254;
  option broadcast-address 172.22.20.255;

  pool {
    range 172.22.20.100 172.22.20.200;
    allow unknown clients;
  }
}

# vlan 10 VMNet
subnet 172.22.10.0 netmask 255.255.255.0 {
  option routers 172.22.10.254;
  option broadcast-address 172.22.10.255;

  pool {
    range 172.22.10.100 172.22.10.200;
    allow unknown clients;
  }
}

Do you have any clue?

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  • This really doesn't have anything to do with ESXi, and more to do with your switch's configuration. Can you reach out to Cumulus for support?
    – ewwhite
    Commented Mar 11, 2016 at 12:36
  • I wasn't sure if it was something weird with esxi or cumulus. I will contact them soon but I just wanted to know that its not something stupid that I may have missed. Commented Mar 12, 2016 at 0:01

2 Answers 2

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Each VLAN is a separate network. In order to service DHCP clients in both networks the DHCP server either needs an interface in each of those networks or you need to use a DHCP relay agent in the network where the DHCP server doesn't have an interface so that the DHCP relay agent can forward DHCP broadcasts to the DHCP server.

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  • Above I listed the interfaces in /etc/default/isc-dhcp-server Commented Mar 12, 2016 at 0:02
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Ok I may be guessing here, but in my opinion there is some issue as to how youhave configured your DHCP server. For this to work you need to configure 2 DHCP servers on two VLANS (VLAN 10 & VLAN 20) to provide IP in the same range for the .10 & .20 respectively.

You wont notice the issue when manually configuring the same. Your have to run another DHCP server on VLAN 20 with the range 172.22.20.1/24 - 172.22.20.254/24

See if it helps.

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  • The switch is the one that serves dhcp so there isnt any other dhcp server. The switch should be able to serve dhcp requests on multiple interfaces. Both bridges br-main and vlan20 have gotten dhcp. The issue is vlan10 for some reason. Commented Mar 11, 2016 at 6:33
  • My bad, I thought the one with vlan 20 is the main culprit. Anyway, the switch serves DHCP to the hosts only on the basis of vlan. The server needs to be configured to send out DHCP for .10 via VLAN 10 so that all devices in VLAN 10 gets the IP. for that you need to configure the DHCP server using a virtual interface with VLAN 10 and then go about configuring the DHCP server using that.
    – ABHISHEK
    Commented Mar 11, 2016 at 6:35

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