Dell PowerSwitch S4820T 9.50.1 Configuration Guide for the S4820T System - Page 326
Con the System for User Port Stacking (Option 230), Con Secure DHCP, Option 82
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• Management routes added by the DHCP client have higher precedence over the same statically configured management route. Static routes are not removed from the running configuration if a dynamically acquired management route added by the DHCP client overwrites a static management route. • Management routes added by the DHCP client are not added to the running configuration. NOTE: Management routes added by the DHCP client include the specific routes to reach a DHCP server in a different subnet and the management route. Configure the System for User Port Stacking (Option 230) Set the stacking-option variable to provide stack-port detail on the DHCP server when you set the DHCP offer. A stack can be formed when the units are connected. Option 230 is the option for user port stacking. Use it to create up to eight stack groups. Define the configuration parameters on the DHCP server for each chassis based on the chassis MAC address. Configure the following parameters: • unit number • priority • stack group ID The received stacking configuration is always applied on the master stack unit. option #230 "unit-number:3#priority:2#stack-group:14" Configure Secure DHCP The following feature is available on the S4820T platform, except where noted. 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. • 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 sub-options, circuit ID and remote ID. Circuit ID Remote ID This is the interface on which the client-originated message is received. 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. 326 Dynamic Host Configuration Protocol (DHCP)
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