Policy Route - ZyXEL Communications NXC5200 User Manual

DSCP Marking and Per-Hop Behavior
DiffServ defines a new DS (Differentiated Services) field to replace the Type of
Service (TOS) field in the IP header. The DS field contains a 2-bit unused field and
a 6-bit DSCP field which can define up to 64 service levels. The following figure
illustrates the DS field.
DSCP is backward compatible with the three precedence bits in the ToS octet so
that non-DiffServ compliant, ToS-enabled network device will not conflict with the
DSCP mapping.
The DSCP value determines the forwarding behavior, the PHB (Per-Hop Behavior),
that each packet gets across the DiffServ network. Based on the marking rule,
different kinds of traffic can be marked for different kinds of forwarding. Resources
can then be allocated according to the DSCP values and the configured policies.

12.2 Policy Route

Click Configuration > Network > Routing to open this screen. Use this screen
to see the configured policy routes and turn policy routing based bandwidth
management on or off.
A policy route defines the matching criteria and the action to take when a packet
meets the criteria. The action is taken only when all the criteria are met. The
criteria can include the user name, source address and incoming interface,
destination address, schedule, IP protocol (ICMP, UDP, TCP, etc.) and port.
The actions that can be taken include:
• Routing the packet to a different gateway or outgoing interface.
• Limiting the amount of bandwidth available and setting a priority for traffic.
NXC5200 User's Guide
DSCP (6 bits)
Chapter 12 Policy and Static Routes
Unused (2 bits)
199