From: Dennis J. Hartmann (dennisjhartmann@hotmail.com)
Date: Sat Sep 24 2005 - 00:13:30 GMT-3
While I do NOT endorse adaptive traffic-shaping for VoIP networks of any
sort, I have come across this scenario in a CCIE practice test. The
question wants the admin to configure a Frame-Relay QoS policy that will
adapt rates based on interface congestion because the interface only runs at
125kbps, but there are multiple PVCs terminating on the interface. This
calls for the frame-relay adaptive-shaping interface-congestion command in
the map-class.
I don't think the answer key is correct though. In the following
policy, the mapclass has the cir and mincir configured and the CBWFQ policy
is being called to carve up the bandwidth on the interface. I don't believe
that the MQC has the ability to configure a policy based on the cir in a
frame map-class. This is why we normally use nested policies to configure
frame-relay traffic-shaping and congestion management. The adaptive
traffic-shaping interface-congestion feature is not a part of the MQC
however.
Given the scenario, I believe the only logical choice would be to put a
bandwith 125 statement on the Serial 0/0 interface so the CBWFQ congestion
management policy is based on 125kbps, not the default of 1544kbps.
Comments and suggestions welcome.
interface Serial0/0
no ip address
encapsulation frame-relay
no fair-queue
frame-relay class Frame-QOS
frame-relay traffic-shaping
policy-map QOS
class QOS-1
priority percent 30
set dscp ef
class QOS-3
bandwidth percent 20
set dscp af33
set fr-de
class QOS-2
bandwidth percent 30
set dscp af31
class class-default
fair-queue
set dscp default
class-map match-all QOS-1
match ip precedence 5
class-map match-all QOS-2
match ip precedence 3
class-map match-all QOS-3
match ip precedence 1
map-class frame-relay Frame-QOS
frame-relay cir 125000
frame-relay mincir 32000
frame-relay adaptive-shaping interface-congestion
service-policy output QOS
Sincerely,
Dennis J. Hartmann
White Pine Communications
CCSI#23402 / CCVP / CCIP / CCNP
Cisco Optical, VPN & IDS Specialist
MCSE
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