QoS ATM Traffic Descriptor Profiles
Quality of Service Guide 693
Any discard decision are performed exclusively at the packet level where the context for the
frame forwarding class and for the 802.1p bit mapping to a forwarding class is known. When
a per-VC queue backs up, a back pressure scheme is applied such that the frames are held in
the per-forwarding class packet queues dedicated to this VC.
This hierarchical scheduling of frames and cells of a given VC terminating on a VPLS
instance provides the flexibility to apply policing and shaping on a per-forwarding class basis
for the Ethernet frames of each VC as well as the option to shape the aggregate cell flow into
the ATM VC back into the customer site.
This QoS model is applied to all router services which include an ATM SAP (VLL, VPLS,
IES and VPRN).
ATM Service Categories
The router supports the following service categories:
• CBR - Constant Bit Rate
• Rt-VBR - Real-Time Variable Bit Rate
• nrt-VBR - Non Real-Time Variable Bit Rate
• UBR/UBR+MIR - Unspecified Bit Rate with Minimum Cell Rate. UBR is a special
case of UBR+MIR where MIR=0.
ATM Traffic Descriptors and QoS Parameters
The router supports the following traffic descriptors for ATM.
Table 48: ATM Traffic Descriptors
Service Category Traffic Descriptors
CBR P0_1 PIR in Kbps (applies to CLP=0 & CLP=1 flows)
Rt-VBR and nrt-VBR P0_1and S0_1 PIR in Kbps (applies to CLP=0 & CLP=1 flows) SIR
in Kbps (applies to CLP=0 & CLP=1 flows)
MBS in cells (applies to CLP=0 and CLP=1 flows)
P0_1 and S0 PIR in Kbps (applies to CLP=0 & CLP=1 flows)
SIR in Kbps (applies to CLP=0 flow only)
MBS in cells (applies to CLP=0 flow only)
UBR/UBR+MIR P0_1 PIR in Kbps (applies to CLP=0 & CLP=1 flows)
MIR in Kbps (applies to CLP=0 & CLP=1 flows)
To Next Page
Loading...
