ZyXEL Communications 3.1 User Manual
Chapter 8 Route
ZyWALL (ZLD) CLI Reference Guide
104
8.2.1 Assured Forwarding (AF) PHB for DiffServ
Assured Forwarding (AF) behavior is defined in RFC 2597. The AF behavior group defines four AF
classes. Inside each class, packets are given a high, medium or low drop precedence. The drop
precedence determines the probability that routers in the network will drop packets when
congestion occurs. If congestion occurs between classes, the traffic in the higher class (smaller
numbered class) is generally given priority. Combining the classes and drop precedence produces
the following twelve DSCP encodings from AF11 through AF43. The decimal equivalent is listed in
brackets.
classes. Inside each class, packets are given a high, medium or low drop precedence. The drop
precedence determines the probability that routers in the network will drop packets when
congestion occurs. If congestion occurs between classes, the traffic in the higher class (smaller
numbered class) is generally given priority. Combining the classes and drop precedence produces
the following twelve DSCP encodings from AF11 through AF43. The decimal equivalent is listed in
brackets.
8.2.2 Policy Route Command Example
The following commands create two address objects (TW_SUBNET and GW_1) and insert a policy
that routes the packets (with the source IP address TW_SUBNET and any destination IP address)
through the interface ge1 to the next-hop router GW_1. This route uses the IP address of the
outgoing interface as the matched packets’ source IP address.
that routes the packets (with the source IP address TW_SUBNET and any destination IP address)
through the interface ge1 to the next-hop router GW_1. This route uses the IP address of the
outgoing interface as the matched packets’ source IP address.
Table 45
Assured Forwarding (AF) Behavior Group
CLASS 1
CLASS 2
CLASS 3
CLASS 4
Low Drop Precedence
AF11 (10)
AF21 (18)
AF31 (26)
AF41 (34)
Medium Drop Precedence
AF12 (12)
AF22 (20)
AF32 (28)
AF42 (36)
High Drop Precedence
AF13 (14)
AF23 (22)
AF33 (30)
AF43 (38)
Router(config)# address-object TW_SUBNET 192.168.2.0 255.255.255.0
Router(config)# address-object GW_1 192.168.2.250
Router(config)# policy insert 1
Router(policy-route)# description example
Router(policy-route)# destination any
Router(policy-route)# interface ge1
Router(policy-route)# next-hop gateway GW_1
Router(policy-route)# snat outgoing-interface
Router(policy-route)# source TW_SUBNET
Router(policy-route)# exit
Router(config)# show policy-route 1
index: 1
active: yes
description: example
user: any
schedule: none
interface: ge1
tunnel: none
sslvpn: none
source: TW_SUBNET
destination: any
DSCP code: any
service: any
nexthop type: Gateway
nexthop: GW_1
nexthop state: Not support
auto destination: no
bandwidth: 0
bandwidth priority: 0
maximize bandwidth usage: no
SNAT: outgoing-interface
DSCP marking: preserve
amount of port trigger: 0
Router(config)#