Motorola Series Switch WS5100 - Manual (Page 26)

1-16 WS5100 Series Switch System Reference Guide
flow having UPSD enabled. After the AP acknowledges the trigger frame, it transmits the frames in its UPSD
power save buffer addressed to the triggering switch.
UPSD is well suited to support bi-directional frame exchanges between a voice STA and its AP
1.2.3 Wired Switching
The switch includes the following wired switching features:
• DHCP Servers
• DDNS
• GRE Tunneling
• VLAN Enhancements
• Interface Management
• Multiple WLAN Support
1.2.3.1 DHCP Servers
Dynamic Host Configuration Protocol (DHCP) allows hosts on an IP network to request and be assigned IP
addresses, and discover information about the network to which they are attached. Configure address pools
for each subnet, and whenever a DHCP client in that subnet requests an IP address, the DHCP server assigns
an IP address from the address pool configured for that subnet.
When a DHCP server allocates an address for a DHCP client, the client is assigned a lease, which expires
after an pre-determined interval. Before a lease expires, clients (to which leases are assigned) are expected
to renew them to continue to use the addresses. Once the lease expires, the client is no longer permitted to
use the leased IP address. For information on defining the switch DHCP configuration, see
DHCP Server Settings on page 5-3.
1.2.3.2 DDNS
Dynamic DNS (DDNS) is a method of keeping a domain name linked to a changing IP address. Typically, when
a user connects to a network, the user’s ISP assigns it an unused IP address from a pool of IP addresses. This
address is only valid for a short period. Dynamically assigning IP addresses increases the pool of assignable
IP addresses. DNS maintains a database to map a given name to an IP address used for communication on
the Internet. The dynamic assignment of IP addresses makes it necessary to update the DNS database to
reflect the current IP address for a given name. Dynamic DNS updates the DNS database to reflect the
correct mapping of a given name to an IP address.
1.2.3.3 GRE Tunneling
GRE tunnelling extends a WLAN across a Layer 3 network using standards based GRE tunneling technology.
• GRE tunnels need to be explicitly provisioned on the switch as well as the tunnel termination device
present at the other end of the Layer 3 network.
• One or more WLANS on the switch are then mapped to the GRE tunnel interface. The configuration is
very similar to mapping WLANs to VLANs.
• All IP packets received from MUs on the WLAN are encapsulated in GRE and sent across the Layer 3
network. The tunnel termination device at the other end decapsulates the GRE header and routes the
inner IP packet to its original destination.