Cisco 500 Series Administration Manual page 344

IP Configuration
Overview
Cisco 500 Series Managed Switch Administration Guide
If the device does not receive a DHCPv4 response in 60 seconds, it continues to
send DHCPDISCOVER queries, and adopts the default IPv4 address:
192.168.1.254/24.
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 IPv4 addresses, the device issues
DHCPv4 requests until it is assigned an IPv4 address from a DHCPv4 server. In
Layer 2 system mode, only the management VLAN can be configured with a static
or dynamic IP address. In Layer 3 system mode, all the interface types (ports,
LAGs, and/or VLANs) on the device can be configured with a static or dynamic IP
address.
The IP address assignment rules for the device are as follows:
• When in Layer 2 system mode, unless the device is configured with a static
IP address, it issues DHCPv4 requests until a response is received from the
DHCP 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 green 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 green. The LED flashes
when the device is acquiring an IP address and is currently using the factory
default IP address 192.168.1.254.
• The same rules apply when a client must renew the lease, prior to its
expiration date through a DHCPREQUEST message.
• With factory default settings, when no statically-defined or DHCP-acquired
IP address is available, the default IP address is used. When the other IP
addresses become available, the addresses are automatically used. The
default IP address is always on the management VLAN.
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