Configuring IP Addressing

IP Configuration

DHCP/Bootp Operation

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Overview. DHCP/Bootp is used to provide configuration data from a DHCP or Bootp server to the switch. This data can be the IP address, subnet mask, default gateway, Timep Server address, and TFTP server address. If a TFTP server address is provided, this allows the switch to TFTP a previously saved configuration file from the TFTP server to the switch. With either DHCP or Bootp, the servers must be configured prior to the switch being connected to the network.

The switches covered in this guide are compatible with both DHCP and Bootp servers.

The DHCP/Bootp Process. Whenever the IP Config parameter in the switch or in an individual VLAN in the switch is configured to DHCP/Bootp (the default), or when the switch is rebooted with this configuration:

1.DHCP/Bootp requests are automatically broadcast on the local network. (The switch sends one type of request to which either a DHCP or Bootp server can respond.)

2.When a DHCP or Bootp server receives the request, it replies with a previously configured IP address and subnet mask for the switch. The switch also receives an IP Gateway address if the server has been config- ured to provide one. In the case of Bootp, the server must first be configured with an entry that has the switch’s MAC address. (To determine the switch’s MAC address, refer to Appendix D, “MAC Address Manage- ment”.) The switch properly handles replies from either type of server. If multiple replies are returned, the switch tries to use the first reply.)

If you manually configure default gateway, TTL, TimeP, and/or SNTP parameters on the switch, it ignores any values received for the same parameters via DHCP or Bootp.

If the switch is initially configured for DHCP/Bootp operation (the default), or if it reboots with this configuration, it begins sending request packets on the network. If the switch does not receive a reply to its DHCP/Bootp requests, it continues to periodically send request packets, but with decreasing fre- quency. Thus, if a DHCP or Bootp server is not available or accessible to the switch when DHCP/Bootp is first configured, the switch may not immediately receive the desired configuration. After verifying that the server has become accessible to the switch, reboot the switch to re-start the process immediately.

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