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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 WAN Aggregation Routers
Minimum CIR
Recommendation:
mincir set to CIR.
The minimum CIR is the transmit value a Frame Relay router will "rate down" to when Backward
Explicit Congestion Notifications (BECNs) are received. By default, Cisco IOS sets the minimum CIR
to CIR/2. However, to maintain consistent service-levels, it is recommended that you disable adaptive
shaping and set the minimum CIR equal to the CIR (which means there is no "rating down").
High-Speed FRTS Parameter Summary
In summary:
·
CIR is set to the PVC speed
·
Bc is set to CIR/100
·
Be is set to 0
·
Minimum CIR is equal to the CIR
No LFI mechanism is required on WAN links above 768 kbps.
Note
cRTP can be used on high-speed Frame Relay links, but do so with caution on WAN aggregators that
serve a large number of remote sites. CPU performance should first be evaluated when enabling cRTP
on high-speed links.
For more information on cRTP, see
.
Example 4-7
High-Speed Frame Relay Link
interface Serial0/1
description Parent FR Link
no ip address
encapsulation frame-relay
frame-relay traffic-shaping
This command enables FRTS on the main interface.
!
interface Serial0/1.50 point-to-point
description FR Link to BRANCH#50
bandwidth 1536
ip address 10.200.50.1 255.255.255.252
frame-relay interface-dlci 150
class FRTS-1536kbps
This command applies the FRTS map-class to the DLCI.
!
...
!
map-class frame-relay FRTS-1536kbps
frame-relay cir 1536000
frame-relay bc 15360
frame-relay be 0
frame-relay mincir 1536000
no frame-relay adaptive-shaping
service-policy output WAN-EDGE
This command applies the MQC policy to the FRTS map-class.