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Cisco Bug: CSCun26512 - dhcp relay support with URPF cause DROP at INGRESS using customer topo

Last Modified

Sep 17, 2018

Products (1)

  • Cisco Nexus 6000 Series Switches

Known Affected Releases


Description (partial)

dhcp relay support with URPF cause DROP at INGRESS using customer topo

configuring DHCP Relay and URPF on interface vlan 363 on the N6K-14a and N6K-14b switches, if the DHCP Discover (client broadcast) arrived at N6K-14b (Active HSRP), then the DHCP Relay will forward the DHCP discover packet from N6K-14b as uni-cast (using DHCP Relay) to N5K48-2 and then to the DHCP server, then the DHCP server could uni-cast a Offer back through N5K48-1 and over to N6k-14a, then these offers has to be forwarded to the N6K-14b since URPF is configured on the DHCP Discover was send from N6K-14b. 
The issue is, if this is the route that was traversed for the DHCP Offer, then once the DHCP Offers are send back to N6K-14b over the MCT, the MCT (VPC10) drops the DHCP Offers.
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