Reference Guide

Table Of Contents
Example of the show ip interface Command
Dell#show ip int tengig 1/3
TenGigabitEthernet 1/3 is up, line protocol is down
Internet address is 10.11.0.1/24
Broadcast address is 10.11.0.255
Address determined by user input
IP MTU is 1500 bytes
Helper address is 192.168.0.1
192.168.0.2
Directed broadcast forwarding is disabled
Proxy ARP is enabled
Split Horizon is enabled
Poison Reverse is disabled
ICMP redirects are not sent
ICMP unreachables are not sent
Configure the System for User Port Stacking
When you set the DHCP offer on the DHCP server, you can set the stacking-option variable to provide
the stack-port detail so a stack can be formed when you connect the units.
Configure Secure DHCP
DHCP as defined by RFC 2131 provides no authentication or security mechanisms. Secure DHCP is a suite
of features that protects networks that use dynamic address allocation from spoofing and attacks.
This section includes the following:
Option 82
DHCP Snooping
Dynamic ARP Inspection
Source Address Validation
Option 82
RFC 3046 (the relay agent information option, or Option 82) is used for class-based IP address
assignment.
The code for the relay agent information option is 82, and is comprised of two suboptions, circuit ID and
remote ID.
Circuit ID This is the interface on which the client-originated message is received.
Remote ID This identifies the host from which the message is received. The value of this
suboption is the MAC address of the relay agent that adds Option 82.
The DHCP relay agent inserts Option 82 before forwarding DHCP packets to the server. The server can
use this information to:
track the number of address requests per relay agent. Restricting the number of addresses available
per relay agent can harden a server against address exhaustion attacks.
associate client MAC addresses with a relay agent to prevent offering an IP address to a client
spoofing the same MAC address on a different relay agent.
assign IP addresses according to the relay agent. This prevents generating DHCP offers in response to
requests from an unauthorized relay agent.
Dynamic Host Configuration Protocol (DHCP)
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