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Figure 32. Client and Server Messaging
Implementation Information
The 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 access
control lists (ACLs) internally to implement this feature and as such, you cannot apply ACLs to an
interface which has IP source address validation. If you configure IP source address validation on a
member port of a virtual local area network (VLAN) and then apply an access list to the VLAN, the
system displays the first line in the following message. If you first apply an ACL to a VLAN and then
enable IP source address validation on one of its member ports, the system 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.
• The system provides 40K entries that can be divided between leased addresses and excluded
addresses. By extension, the maximum number of pools you can configure depends on the subnet
mask that you give to each pool. For example, if all pools were configured for a /24 mask, the total
would 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. The system displays an error
message for configurations that exceed the allocated memory.
• The Z9500 switch supports 4K DHCP Snooping entries.
• All platforms support Dynamic ARP Inspection on 16 VLANs per system. For more information, refer to
Dynamic ARP Inspection.
NOTE: If the DHCP server is on the top of rack (ToR) and the VLTi (ICL) is down due to a failed
link, when a VLT node is rebooted in JumpStart mode, it is not able to reach the DHCP server,
resulting in bare metal provisioning (BMP) failure.
Dynamic Host Configuration Protocol (DHCP)
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