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Chapter 10 - IP Interface
IPv4
Layer 2 IP Addressing
The device has one IPv4 address and up to two IPv6 interfaces in the management VLAN. This IP
address and the default gateway can be configured manually, or by DHCP. The static IP address
and default gateway are configured on the IPv4 Interface page. The device uses the default
gateway, if configured, to communicate with devices that are not in the same IP subnet as the
device. By default, VLAN 1 is the management VLAN, but this can be modified. The device can
only be reached at the configured IP address through its management VLAN.
The factory default setting of the IPv4 address configuration is DHCPv4. This means that the
device acts as a DHCPv4 client, and sends out a DHCPv4 request during boot up.
If the device receives a DHCPv4 response from the DHCPv4 server with an IPv4 address, it sends
Address Resolution Protocol (ARP) packets to confirm that the IP address is unique. If the ARP
response shows that the IPv4 address is in use, the device sends a DHCPDECLINE message to
the offering DHCP server, and sends another DHCPDISCOVER packet that restarts the process.
If the device does not receive a DHCPv4 response in 60 seconds, it continues to send
DHCPDISCOVER queries, and adopts the default IPv4 address: 192.168.1.251/24.
IP address collisions occur when the same IP address is used in the same IP subnet by more than
one device. Address collisions require administrative actions on the DHCP server and/or the
devices that collide with the device.
When a VLAN is configured to use dynamic IP addresses, the device issues DHCPv4 requests
until it is assigned an IPv4 address from a DHCPv4 server. The management VLAN can be
configured with a static or dynamic IP address.
The IP address assignment rules for the device:
•
Unless the device is configured with a static IPv4 address, it issues DHCPv4 queries until
a response is received from a DHCPv4 server.
•
If the IP address on the device is changed, the device issues gratuitous ARP packets to the
corresponding VLAN to check IP address collisions. This rule also applies when the device
reverts to the default IP address.
•
The system status LED changes to solid blue when a new unique IP address is received
from the DHCP server. If a static IP address has been set, the system status LED also
changes to solid blue. The LED flashes when the device is acquiring an IP address and is
currently using the factory default IP address 192.168.1. 251.
•
The same rules apply when a client must renew the lease, prior to its expiration date
through a DHCPREQUEST message.