Configuration per interface, Configuration per interface -12 – Enterasys Networks Security Router X-PeditionTM User Manual
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Mechanisms Providing QoS
12-12 Configuring Quality of Service
WRED. Traffic marked with a lower drop probability is assigned a higher MaxP, and bigger
thresholds for MinTh and MaxTh than traffic marked with DSCP values having a higher drop
level. Because higher drop DSCPs have a lower MinTh, as the queue grows, the XSR starts
discarding them earlier than low drop DSCPs. Also, the XSR drops them more often because they
have a higher drop probability (MaxProb). The end effect is that packets marked with high-drop
DSCP values are discarded more frequently.
The XSR treats RED as a subclass of WRED because it becomes equivalent to RED when all DSCP
or precedence values have the same minth, maxth, and maxprob values. While you can implement
RED by configuring WRED, RED may still be configured by itself using the
random-detect
command as illustrated in the following example. These two configurations are equivalent - both
configure RED with MinTh=10, MaxTh=20 and MaxProb=1 although the first uses random-detect
while the second uses WRED.
XSR(config)#policy-map ppwe
XSR(config-pmap<ppwe>)#class bus
XSR(config-pmap-c<bus>)#random-detect 10 20 10
XSR(config)#policy-map ppwe
XSR(config-pmap<ppwe>)#class bus
XSR(config-pmap-c<bus>)#random-detect dscp-based
XSR(config-pmap-c<bus>)#random-detect dscp default 10 20 10
Configuration per Interface
QoS can be configured on both LAN and WAN interfaces, sub-interfaces (Frame Relay DLCI,
ATM, Ethernet VLAN) , and virtual interfaces (Dialer, VPN).
illustrates the options:
The Dialer interface is a virtual interface in the sense that it does not have a corresponding
transmit port (serial or Ethernet). Only after it dials does the dialer interface bind to one of the
resources from the dialing pool (Serial port) and establish a data path. Service policy applied to
Note: Drop Tail and WRED cannot be used on the same queue simultaneously - queue-limit and
random-detect are mutually exclusive. If random-detect is set on a queue, queue-limit cannot be set
as well until WRED is removed.
Table 12-2 Configuration Options by LAN/WAN Interface
Function
Ethernet
Serial
PPP
MLPPP
FR DLCI
Dialer
VPN
CBWFQ
Y
Y
Y
Y
Y
Y
Y
Priority Queue
Y
Y
Y
Y
Y
Y
Y
Traffic Policing
Y
Y
Y
Y
Y
Y
Y
Random Early Detect
Y
Y
Y
Y
Y
Y
Y
WRED
Y
Y
Y
Y
Y
Y
Y
Traffic Shaping per class
Y
Y
Y
Y
Y
Y
Y
Traffic Shaping per policy
Y
Y
Y
Y
Y
Y
Y
Service Map input
Y
Y
Y
Y
Y
Y
Y
Service Map output
Y
Y
Y
Y
Y
Y
Y