Implementation Information; Configure The System To Be A Dhcp Server - Dell Z9500 Configuration Manual

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 to
apply an access list to the VLAN, Dell Networking OS 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, Dell 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 configured L2 ports, any IP ACL, MAC ACL, or DHCP
source address validation ACL does not block DHCP packets.
• Dell Networking OS provides 40000 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. Dell
Networking OS displays an error message for configurations 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
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.

Configure the System to be a DHCP Server

A DHCP server is a network device that has been programmed to provide network configuration parameters to clients upon
request. Servers typically serve many clients, making host management much more organized and efficient.
The following table lists the key responsibilities of DHCP servers.
Table 25. DHCP Server Responsibilities
DHCP Server Responsibilities
Address Storage and Management
Configuration Parameter Storage and Management
Lease Management
Responding To Client Requests
Providing Administration Services
Description
DHCP servers are the owners of the addresses used by DHCP
clients.The server stores the addresses and manages their use,
keeping track of which addresses have been allocated and
which are still available.
DHCP servers also store and maintain other parameters that
are sent to clients when requested. These parameters specify
in detail how a client is to operate.
DHCP servers use leases to allocate addresses to clients for a
limited time. The DHCP server maintains information about
each of the leases, including lease length.
DHCP servers respond to different types of requests from
clients, primarily, granting, renewing, and terminating leases.
DHCP servers include functionality that allows an
administrator to implement policies that govern how DHCP
performs its other tasks.
Dynamic Host Configuration Protocol (DHCP)
Dynamic ARP
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