Concept Guide

Figure 35. Client and Server Messaging
Implementation Information
The following describes DHCP implementation.
Dell EMC Networking implements DHCP based on RFC 2131 and RFC 3046.
IP source address validation is a sub-feature of DHCP Snooping; the Dell EMC 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
congure IP source address validation on a member port of a virtual local area network (VLAN) and then to apply an access list to the
VLAN, Dell EMC Networking OS displays the rst line in the following message. If you rst apply an ACL to a VLAN and then enable IP
source address validation on one of its member ports, Dell EMC Networking 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 congured L2 ports, any IP ACL, MAC ACL, or DHCP
source address validation ACL does not block DHCP packets.
Dell EMC Networking OS provides 40000 entries that can be divided between leased addresses and excluded addresses. By extension,
the maximum number of pools you can congure depends on the subnet mask that you give to each pool. For example, if all pools were
congured for a /24 mask, the total would be 40000/253 (approximately 158). If the subnet is increased, more pools can be congured.
The maximum subnet that can be congured for a single pool is /17. Dell EMC Networking OS displays an error message for
congurations that exceed the allocated memory.
This platform supports 4000 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 BMP (Bare Metal Provisioning) mode, it is not able to reach the DHCP server, resulting in BMP failure.
Congure the System to be a DHCP Server
A DHCP server is a network device that has been programmed to provide network conguration parameters to clients upon request.
Servers typically serve many clients, making host management much more organized and ecient.
NOTE
: If the management port is associated with any non-default VRF, then the ip address dhcp command does not work.
The following table lists the key responsibilities of DHCP servers.
Table 25. DHCP Server Responsibilities
DHCP Server Responsibilities Description
Address Storage and Management DHCP servers are the owners of the addresses used by DHCP
clients.The server stores the addresses and manages their use,
Dynamic Host Conguration Protocol (DHCP) 321