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SGE2000 DHCP Relay Issue

kanephil1
Level 1
Level 1

I am looking for some help with DHCP Relay on a SGE2000 switch.

I have configured two VLANs on the switch, VLAN2 (192.168.10.x/24) and VLAN3 (192.168.9.x/24). I have the switch in Layer 3 mode. I have configured the DHCP relay server of 192.168.10.4 and the DHCP Interfaces as VLAN3. All of the IP Static Routes were generated by the switch.

If I put a client computer on a port that is Untagged VLAN 3 and try to get a DHCP address from the server on an Untagged VLAN 2 port I never get a response back.

I have done some packet captures and here is what I have found:

  1. I see the DHCP broadcast on the client computer
  2. I see the DHCP Request on the DHCP server coming from the IP assiged to the switch on VLAN 3 (192.168.9.254)
  3. I see the DHCP server respond with a DHCP Offer
  4. The DHCP offer never gets to the client computer

I can't seem to get a DHCP address to any system not on the same VLAN as the DHCP server. Option 82 is disable and I did try enabling it, which made no difference.

Any help would be great.

Thanks,

Phil

1 Accepted Solution

Accepted Solutions

David Hornstein
Level 7
Level 7

Hi phil,

Have you created a static route on the DHCP server that points back to the 192.168.9.0/24 network.

The gateway for that network,  from the DHCP relay servers perspective,  is the VLAN2 IP address of the SGE2000 switch.

i would think that if you tried to ping the VLAN3 switch  IP address from the DHCP server now,  you will not get a reply.

When you create a static or persistant route in the DHCP server,   you then should be able to ping VLAN3 IP address of the switch.

regards Dave

View solution in original post

2 Replies 2

David Hornstein
Level 7
Level 7

Hi phil,

Have you created a static route on the DHCP server that points back to the 192.168.9.0/24 network.

The gateway for that network,  from the DHCP relay servers perspective,  is the VLAN2 IP address of the SGE2000 switch.

i would think that if you tried to ping the VLAN3 switch  IP address from the DHCP server now,  you will not get a reply.

When you create a static or persistant route in the DHCP server,   you then should be able to ping VLAN3 IP address of the switch.

regards Dave

Dave,

Thanks for the response.  After reading your post I tried to ping the switch on the 192.168.9.0/24 network and could not get there.  Once I switched my default gateway on my DHCP server to the switch IP on the same VLAN everything worked.  I can now get DHCP address on VLAN 3.

Thanks,

Phil

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