Table of Contents
Advertisement
Configuring Bridging
82
EtherXtend User's Guide
An uplink bridge uses one bridge interface in a VLAN as a default,
and traffic from all other interfaces exits the system from this
interface. As the default interface, packets entering the system on this
interface do not have their source MAC addresses learned and
associated with this interface. Traffic coming into this uplink
interface is sent to the interface where the address has been learned. If
the frame is a broadcast, it is filtered, unless it is an ARP or DHCP
message that meets some special criteria. Unicasts received on an
uplink port are forwarded to the downlink where the MAC address
was learned.
Uplink bridge interfaces require an additional bridge-path
configuration to set a default path for either a specific VLAN or
globally for the system onto the uplink bridge. If an uplink is missing
this configuration, traffic will not flow across the asymmetric VLAN.
–
Downlink bridge
A downlink bridge is used in conjunction with an uplink bridge.
where the uplink bridge is the path upstream to the network, and the
downlink bridge is the learning interface facing subscribers. Traffic
coming into this interface is forwarded to the uplink regardless of the
destination MAC address. Broadcasts and unicasts (known and
unknown) will be sent out the default interface, which is the uplink
bridge for the VLAN.
Packets entering the system on this interface have their source MAC
addresses learned and associated with this interface. Because this
interface is not a default, it is required to learn MAC addresses, so
that frames from the network that come in on the uplink bridge can be
sent to the correct downlink bridge. Broadcasts received on a
downlink are sent to the uplink (default) without filtering. Broadcasts
will not flow to other downlinks as long as forwardtodefault
parameter is set to true. Downlink ports learn MAC addresses.
–
Intralink bridge
An intralink bridge is used in conjunction with an uplink bridge,
where the uplink bridge is the path upstream to the network, and the
intralink forwards traffic with unknown MAC addresses or multicasts
to the configured bridge interface without attempting to learn the
addresses of the attached devices or network. Traffic coming into this
interface is forwarded to the uplink regardless of the destination
MAC address. Broadcasts, multicasts, and unicasts (known and
unknown) will be sent out the default interface, which is the uplink
bridge for the VLAN.
Packets entering the system on this interface will not have their
source MAC addresses learned since this interface is not used when a
MAC is known.
Advertisement
Table of Contents
