Recently deployed Nexus 7010 in the core of our network.
DHCP Relay is configured on all SVIs, but certain hosts cannot PXE Boot or obtain DHCP leases.
Various servers set the "broadcast flag" in the DHCP header when they send DHCP-Discover packets during PXE. When the DHCP server sends back a DHCP-Offer (with the Broadcast flag set) , the Nexus 7000 fails to forward the packet out the SVI. However, if the DHCP Client were to clear the Broadcast flag (Unicast) in its DHCP-Discover packet, the subsequent DHCP-Offer will also have the Broadcast flag cleared (Unicast), and will be sucessfully forwarded out the SVI.
After doing some packet captures & debugs I believe I've isolated this issue to be a side effected of FabricPath FTAG selection & the DHCP Relay implementation in nx-os.
CORE1 (root for FTAG1) was sending the broadcast dhcp offer via the path for FTAG2 (CORE2 being root for FTAG2). CORE2 would receive the packet but not forward it along the multi destination tree ( due to DHCP Relay being configured). This is why DHCP in Unicast mode didn't have any issues, since DHCP Relay would ignore the Unicast packet being sent to the dhcp client.
Introduction This article will help you understand the steps on how to
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==================== VIC FNIC driver does not support Virtual Volumes (
second level LUN ID ) An enhancement request has been created to track
this feature - CSCux64473 UPDATE - 12-14-2016 We made some traction on
the enhancement request - The Fix is in t...