I've got a QoS question for the group; I'm not a QoS buff, at least not
on the nitty gritty details. I'm trying to set up some basic QoS on a
3Mbps PtP Ethernet link. One side uses a full interface for the link on
a 2821. My side uses a 1Q sub-interface on a hardwired GigE port in a
2821. I can't apply a matching QoS config due to the sub-interface. I
found this guide on how to approach QoS on a Ethernet sub-interface. It
specifically states that I have to use a hierarchical QoS policy with
shaping in the parent before I can use CBWFQ on the sub-int.
http://www.cisco.com/en/US/tech/tk543/tk545/technologies_tech_note09186a0080114326.shtml
The far side uses this:
class-map match-any SIGNAL
match ip dscp af41
match ip dscp af31
match ip dscp cs3
class-map match-any VOICE
match ip dscp ef
match ip rtp 16384 16383
!
policy-map WAN_QOS
class VOICE
priority percent 35
set dscp ef
class SIGNAL
bandwidth percent 5
set dscp af31
class class-default
fair-queue
I'm looking at applying this:
class-map match-any voip-rtp
match ip dscp ef
match ip rtp 16384 16383
!
class-map match-any voip-control
match ip dscp af41
match ip dscp af31
match ip dscp cs3
policy-map voip-child
class voip-rtp
priority percent 35
set dscp ef
class voip-control
bandwidth percent 5
set dscp af31
!
policy-map voip-parent
class class-default
shape average ABC
!
service-policy voip-child
Overall I think that would work though I'm sure it needs some tweaking.
My holdup is the shape average value. I'm trying to understand what
it is that I'm shaping with that command. Should the shape value be the
max I'm allowing for the VoIP classes referenced by the policy map, the
max for the link, or some other value that I'm not thinking of? If it
is the voip classes will that affect my percentage commands in the child
classes? ie, if the shaping was set at 1Mbps would the 35% in the child
come out at 350k?
Thanks
Justin
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