Samsung Ubigate iBG3026 Configuration Manual page 256

CHAPTER 20. VLAN forwarding with QoS
At the POP, tagged traffic is forwarded to a VLAN trunk port on the Ethernet
switch. Routing between customer VLANs is provided by the POP router
using sub-interfaces on the Gigabit Ethernet VLAN trunk. The customer LAN
subnet is extended all the way to the POP router making remote management
of LAN services(for example, DHCP, file servers. SMTP) possible.
The VLAN forwarding feature has the added benefit of being able to support
non-IP traffic since all traffic is forwarded based only on the Layer 2 VLAN
tag. Although iBG3026 products do not communicate using non-IP Layer 3
protocols, iBG3026uters can forward these protocols.
The management VLAN feature provides in-band communication with the
iBG3026 as well as the Ethernet switches while remaining separate from
customer traffic. The iBG3026 will examine the destination IP address of any
packets received on the management VLAN.
If the destination is the iBG3026, the address of the packet will be forwarded
to the IP layer for local processing. If the address does not match the address
of the iBG3026, the packet will be forwarded to all interfaces configured for
the management VLAN with the exception of the interface where it was
received. This allows all transmission equipment to be managed in a single,
flat VLAN.
When the iBG3026 generates traffic on to the management VLAN, an ARP
request is generated in the direction of the VLAN's default route. If no default
is configured, the ARP request will be generated in all possible directions, and
the interface receiving the response will be cached with the reply. The source
MAC address used by the iBG3026 will be associated with the Ethernet port
associated with the management VLAN.
In a multi-tenant unit(MTU) where customer Internet access is through the
Ethernet interface, some form of bandwidth control is necessary to prevent a
high bandwidth customer from blocking others since the uplink out of the
building will typically be less than 10 Mbps. The iBG3026 provides QoS
support to limit customer bandwidth using a committed rate and burst rate,
ensuring that customers get consistent bandwidth performance as other
customers are activated. iBG3026's QoS can be configured based on VLAN
IDs, in increments of 64 kbps providing greater control than what is normally
available in Ethernet switches.
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