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Switch not forwarding the DHCP offer to client VLAN

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TitleSwitch not forwarding the DHCP offer to client VLAN
Symptoms
Client not getting IP from the DHCP server.
Environment
  • All EXOS versions
  • Summit
  • Black Diamond
Cause
When DHCP Discover is sent out on a particular routed VLAN and DHCP offer is received on a different routed VLAN, then switch which performs the bootprelay will not forward the DHCP offer packet to the client VLAN. 

Below is the scenario to explain the behavior:


Lets assume the client is on "Data"VLAN and its DHCP Discover packet gets relayed to VLAN "Uplink" to reach the DHCP server and when the Offer Packet from the DHCP server receives on a different VLAN other than VLAN "Uplink" due to asymmetrical routing then, the Offer is not forwarded out the switch to the client VLAN. Which means the DHCP Offer or ACK should receive by the switch on same VLAN "uplink" for it relay the packet back to the client VLAN. 
Resolution
Routing should be performed in such a way that DHCP Discover and Offer reaches the bootprelay VLAN through same routed interface.
 
Additional notes

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