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Cisco AVVID Network Infrastructure Enterprise Quality of Service Design
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Chapter 4 QoS in an AVVID-Enabled Wide-Area Network
QoS Recommendations for Remote Branch Routers
Remote LAN Edge for Data
For data, service policies are typically applied at the output, but there are exceptions when they can be
applied at the input.
Output Policies
In the following data-only example, data traffic flows are mapped from their DSCP values to their
corresponding 802.1Q CoS values. The policy is applied to only the Data VLAN Fast-Ethernet
sub-interface.
Note
Class-maps that have been defined for the WAN-Edge policies do not need to be redefined
ip cef
!
policy-map REMOTE-LAN-EDGE-OUT
class GOLD-DATA
set cos 2
class SILVER-DATA
set cos 1
class class-default
set cos 0
!
interface FastEthernet0/0
description CAT3500 REMOTE-BRANCH ACCESS-SWITCH
no ip address
load-interval 30
speed auto
duplex auto
!
interface FastEthernet0/0.50
description NATIVE SUBNET 10.1.50.0 DATA
encapsulation dot1Q 50
ip address 10.1.50.1 255.255.255.0
service-policy output REMOTE-LAN-EDGE-OUT
This command applies the MQC policy to the
sub-interface.
For more information about DSCP and COS, see
Input Policies
In keeping with the Differentiated Services model design principle, all traffic should be marked as close
to their sources as possible. This means marking data traffic on campus access switches and at remote
branch access switches. However, circumstances may exist where such classification cannot be made on
the remote branch access switch, such as:
·
The remote branch access switch does not have Layer 3/Layer 4 awareness.
·
Classification needs to be done at the application layer (via NBAR).
In such cases, DSCP classification must be performed at the ingress interface of the remote branch
router.
provides an illustration of this. SAP (identified by TCP port 3200), SQLNET and Citrix
are the most important applications. These are followed in order of importance by e-mail protocols,
TELNET, and R-commands (rsh, rlogin, rexec). Finally, FTP, backups, and peer-to-peer applications are
designated for less-than-best-effort service.