Cisco 15327 - Manual (Page 449)

26-17
Ethernet Card Software Feature and Configuration Guide, R7.2
Chapter 26 Configuring IEEE 802.17b Resilient Packet Ring
Configuring QoS on RPR-IEEE
Configuring QoS on RPR-IEEE
The different priorities of traffic can be configured with rate limiters and prescribed specific bandwidths.
This configuration on each span might be identical (default) or might vary from the other span.
The highest-priority traffic, known as service class A0, can reserve a portion of total ringlet bandwidth
using the reserved keyword. This reservation is propagated throughout the ringlet, and all stations
recognize the bandwidth allocation cumulatively. Reserved A0 ba802.17 RPR defines 3 service classes,
each with unique QOS characteristics.
1. Class A
2. Class B
3. Class C
With this different priorities of traffic can be configured with rate limiters and prescribed specific
bandwidths. This configuration on each span might be identical (default) or might vary from the other
span.
Class A
Class A is highest priority, lowest latency, and lowest jitter class . A has two types - A0 and A1. Can
reserve a portion of the ringlet bandwidth using "reserve" keyword. This bandwidth is known as A0
bandwidth. The A0 bandwidth can only be used for classA traffic. Any Reserved bandwidth that is
unused will remain unused on the ring, Reserved bandwidth is therefore expensive because it reduces
the bandwidth available for best effort. This reservation is propagated throughout the ringlet, and all RPR
stations recognize the bandwidth allocation cumulatively. Reserved A0 bandwidth can be used only by
the station that reserves it. The default allocation is 0 Mbps. The unreserved classA bandwidth is called
the A1 bandwidth. Service class A1 is configured as high-priority traffic in excess of the A0 bandwidth
reservation, and can be rate-limited using the high tx-traffic rate limiter. The default allocation for A1 is
5 Mbps.
ClassB
This is the medium traffic priority. Lower priority than classA, but higher priority than classC. The
medium transmit traffic rate limiter allows a certain amount of traffic to be added to the ringlet that is
not subject to fairness eligibility, but must compete for the unreserved bandwidth with other traffic of
the same service class. This traffic is committed information rate (B-CIR) traffic. The default allocation
is 10 Mbps.
Step 5 Router(config)# no shut Enables the RPR-IEEE interface and changes the
mode from the default passthrough.
Step 6 Router(config)# end Returns to privileged EXEC mode.
Step 7 Router# copy running-config startup-config (Optional) Saves configuration changes to the
TCC2/TCC2P flash database.
Command Purpose