Figure 28. Client and Server MessagingImplementation InformationThe following describes DHCP implementation.• Dell Networking implements DHCP based on RFC 2131 and RFC 3046.• IP source address validation is a sub-feature of DHCP Snooping; the Dell Networking OS uses accesscontrol lists (ACLs) internally to implement this feature and as such, you cannot apply ACLs to aninterface which has IP source address validation. If you configure IP source address validation on amember port of a virtual local area network (VLAN) and then attempt to apply an access list to theVLAN, Dell Networking OS displays the first line in the following message. If you first apply an ACL to aVLAN and then attempt enable IP source address validation on one of its member ports, DellNetworking OS displays the second line in the following message.% Error: Vlan member has access-list configured.% Error: Vlan has an access-list configured.NOTE: If you enable DHCP Snooping globally and you have any configured L2 ports, any IP ACL,MAC ACL, or DHCP source address validation ACL does not block DHCP packets.• Dell Networking OS provides 40K entries that can be divided between leased addresses and excludedaddresses. By extension, the maximum number of pools you can configure depends on the subnetmask that you give to each pool. For example, if all pools were configured for a /24 mask, the totalwould be 40000/253 (approximately 158). If the subnet is increased, more pools can be configured.The maximum subnet that can be configured for a single pool is /17. Dell Networking OS displays anerror message for configurations that exceed the allocated memory.• The Z9000 platform supports 4K DHCP Snooping entries.• All platforms support Dynamic ARP Inspection on 16 VLANs per system. For more information, refer toDynamic ARP Inspection.NOTE: If the DHCP server is on the top of rack (ToR) and the VLTi (ICL) is down due to a failedlink, when a VLT node is rebooted in BMP (Bare Metal Provisioning) mode, it is not able to reachthe DHCP server, resulting in BMP failure.254 Dynamic Host Configuration Protocol (DHCP)
