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Cisco ASR 901 Series Aggregation Services Router Software Configuration Guide
OL-23826-09
Chapter 24 Configuring QoS
Configuring Quality of Service (QoS)
• Congestion Management Limitations
• Shaping Limitations
• ACL-based QoS Restrictions
General QoS Limitations
The following general QoS limitations apply to the Cisco ASR 901 router.
• You can create a maximum of 256 class maps including the class-default class map.
• You can create a maximum of 32 policy-maps.
The following limitations apply to QoS policies on HDLC, PPP, PPP interfaces:
• Input PPP interfaces support only QoS marking policies.
• You can create a maximum of eight match statements within a class map in a service policy applied
to a PPP interface.
• You can create a maximum of eight classes within a policy-map that is applied to a PPP interface.
This number includes the default-class.
• You can have only one priority class within a policy-map applied to a PPP interface.
• The match-all keyword of the class-map command is not supported.
• The following actions are not supported for Egress Policy:
–
Bandwidth value
–
Priority value
–
Set of qosgroup (VLAN Priority)—This is relevant only for Layer 2 transport over MLPPP
interface.
• Requires explicit configuration of class-default with bandwidth percent.
• DSCP marking is not supported for class-default queue.
• All the above restrictions are applicable to MPLS/IP over MLPPP, in addition to the following
specific restrictions.
The following limitations apply to QoS policies on MPLS/IP over MLPPP interfaces:
• Cisco ASR 901 router supports the following features for MLPPP egress—DSCP marking priority,
eight bandwidth queues, link fragmentation, interleave, and queue limits.
• Input policy is not supported.
• EXP marking is not supported for class-default queue.
The following limitations apply to GigabitEthernet interfaces:
• You can apply a maximum of 2 different service policies to GigabitEthernet interfaces
• You can only use the class-default class for HQoS parent service policies applied to egress Gigabit
Ethernet interfaces.
Statistics Limitations
• Input service policies on the GigabitEthernet interface support statistics in bytes.
• PPP and MLPPP interfaces support QoS statistics in packets.
• Output service policies on the Gigabit Ethernet interface support statistics in bytes.