Information Technology Reference
In-Depth Information
As mentioned, certain Cisco IP phones also have a PC port to which it is possible to connect a workstation, and these Cisco IP
phones can re-mark any traffic received from the workstation with CoS 0.
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mls qos trust device cisco-phone:
This command can be used to extend the trust boundary and trust CoS/DSCP values sent
by connected Cisco IP phones.
QoS configuration on Cisco switches varies depending on particular requirements and specific hardware platforms. However, possible
QoS policy for ports connected to conditionally trusted Cisco IP phones might be as follows:
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Cisco switches are configured to conditionally trust Cisco IP phones using the
mls qos trust device cisco-phone
command.
A policy map is attached to switch ports that match voice media and call signaling traffic received on the voice VLAN using
DSCP values, sets appropriate DSCP values, and polices that traffic to ensure that excess voice media traffic is dropped and
excess call signaling traffic is marked down. Any other traffic received either on the voice VLAN or on the access VLAN is
marked as DSCP 0 and policed, with any excess traffic being marked down to scavenger class.
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The
switchport priority extend trust
command can be used to configure the IP phone's access port to trust the priority
received from a connected PC or other device.
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The
switchport priority extend cos
value
command can be used to configure the IP phone's access port to override the
priority on frames received from a connected PC or other device and set it to the specified value.
CuCM CAC and gK: Hub-and-Spoke/Fully Meshed MPLS
When the underlying WAN is Multiprotocol Label Switching (MPLS) based, it is important to consider some important differences in
how CAC should be provisioned over an MPLS WAN compared to how it is provisioned over more traditional (Layer 2) WANs.
First, although it is possible for service providers to configure a true hub-and-spoke customer routing topology over an MPLS Layer 3
VPN, most service providers instead provision an any-to-any routing and connectivity model over which customer traffic flows. The
fact that all sites have direct connectivity can present a few challenges as far as CAC is concerned.
Customer edge (CE) routers in an MPLS Layer 3 VPN peer only with provider edge (PE) routers, not with each other. Also, PE
routers use MP-BGP to advertise customer routes to each other (irrespective of any PE-CE routing protocol). So, the service provider
