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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
interface ATM4/0.60 point-to-point
description ATM Link to BRANCH#60
bandwidth 3000
ip address 10.200.60.1 255.255.255.252
pvc BRANCH#60 0/60
vbr-nrt 3000 3000
This command sets the high ATM AAL5 traffic contract.
tx-ring-limit 3
This command reduces delay caused by the TX ring buffer.
service-policy output WAN-EDGE
This command applies the MQC policy to the ATM PVC.
Tip
For more information, see Configuring ATM.
Slow-Speed ATM Links
Prior to IOS 12.1(5)T, there was no mechanism for fragmenting-and-interleaving over low-speed ATM
links. At that time, a new standard of applying MLP LFI over ATM provided the required minimization
of serialization delay for slow ATM links. Additionally, MLP over ATM requires the MLP bundle to
classify the outgoing packets before they are sent to the ATM VC.
Note
There are two virtual-access interfaces created for each virtual-template. One is the Layer 2 PPP-only
virtual-access. The other is the "bundle" virtual-access interface. It is the bundle interface that takes on
all of the properties of Layer 3 (the IP address, cRTP if configured, etc.). CBWFQ can be applied only
to the bundle interface.
MLP uses the bundle virtual-access interface to reassemble packets received over individual links and
to fragment packets sent out over individual links. The bundle interface inherits its configuration from
the virtual-template specific to MLP.
illustrates how virtual-templates and MLP LFI can be applied in such a scenario.
Example 4-12 Slow-Speed ATM Link Using Virtual-Templates
ip cef
In distributed platforms, use ip cef distributed.
!
...
!
interface ATM4/0
bandwidth 768
no ip address
no atm ilmi-keepalive
!
interface ATM4/0.60 point-to-point
pvc BRANCH#60 0/60
vbr-nrt 768 768
This command sets the high ATM AAL5 traffic contract.
tx-ring-limit 3
This command reduces the delay caused by the TX ring buffer.
protocol ppp Virtual-Template60
This command binds the virtual template to the PVC.
!
interface Virtual-Template60
bandwidth 768
ip address 10.200.60.1 255.255.255.252
service-policy output WAN-EDGE
This command sets the MQC policies for voice and data.
ppp multilink
ppp multilink fragment-delay 10
This command sets the maximum delay to 10 ms
.
ppp multilink interleave
This command enables MLP LFI.