ZyXEL Communications ZYWALL USG 20 Manual page 454

Chapter 28 Bandwidth Management
in a network by grouping similar types of traffic together and treating each type as
a class. You can use CoS to give different priorities to different packet types.
DiffServ (Differentiated Services) is a class of service (CoS) model that marks
packets so that they receive specific per-hop treatment at DiffServ-compliant
network devices along the route based on the application types and traffic flow.
Packets are marked with DiffServ Code Points (DSCPs) indicating the level of
service desired. This allows the intermediary DiffServ-compliant network devices
to handle the packets differently depending on the code points without the need to
negotiate paths or remember state information for every flow. In addition,
applications do not have to request a particular service or give advanced notice of
where the traffic is going.
Connection and Packet Directions
Bandwidth management looks at the connection direction, that is from which zone
the connection was initiated and to which zone the connection is going.
A connection has outbound and inbound packet flows. The ZyWALL controls the
bandwidth of traffic of each flow as it is going out through an interface or VPN
tunnel.
• The outbound traffic flows from the connection initiator to the connection
responder.
• The inbound traffic flows from the connection responder to the connection
initiator.
For example, a LAN1 to WAN connection is initiated from LAN1 and goes to the
WAN.
• Outbound traffic goes from a LAN1 zone device to a WAN zone device.
Bandwidth management is applied before sending the packets out a WAN zone
interface on the ZyWALL.
• Inbound traffic comes back from the WAN zone device to the LAN1 zone device.
Bandwidth management is applied before sending the traffic out a LAN1 zone
interface.
Figure 278
LAN1
454
LAN1
to WAN Connection and Packet Directions
Connection
Outbound
BWM
BWM
Inbound
ZyWALL USG 20/20W User's Guide