Implementation Information - Dell C9000 Series Networking Configuration Manual

Hide thumbs Also See for C9000 Series:

Table of Contents

There are additional messages that are used in case the DHCP negotiation deviates from the process

previously described and shown in the illustration below.

A client sends this message to the server in response to a DHCPACK if the configuration

parameters are unacceptable; for example, if the offered address is already in use. In

this case, the client starts the configuration process over by sending a DHCPDISCOVER.

A client uses this message to request configuration parameters when it assigned an IP

address manually rather than with DHCP. The server responds by unicast.

A server sends this message to the client if it is not able to fulfill a DHCPREQUEST; for

example, if the requested address is already in use. In this case, the client starts the

configuration process over by sending a DHCPDISCOVER.

Figure 34. 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.

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 dhcp binding entries that can be divided between leased addresses and

excluded addresses. By extension, the maximum number of pools you can configure depends on the

Dynamic Host Configuration Protocol (DHCP)