Software Configuration of ATM ISE Line Cards for Cisco 12000 Series Routers
How to Configure Layer 3 Terminated VCs on the 4-Port ATM ISE Line Card
10
Cisco IOS Release 12.0(27)S
Note
For VBR connections in which the sustainable cell rate (SCR) is not equal to the PCR value, the CDVT
is significantly lower.
Decreased VC Throughput
If you configure a VC on a 4-Port OC-12/STM-4 ATM ISE interface with a peak cell rate (PCR) or
sustainable cell rate (SCR) greater than OC-6 (using the
ubr
,
vbr-nrt
,
vbr-rt
, or
cbr
commands), and
attach a traffic policy with MDRR (configured using the
bandwidth
command) to the interface for
specified traffic classes, when traffic on the interface from the specified classes is equal to or greater than
the configured PCR or SCR values, frequent queueing and dequeueing changes occur between the
MDRR queues and may cause a decreased VC throughput.
Decreased throughput is more likely to occur when the traffic consist of small packets and when a high
amount of traffic is sent toward the high-priority queue. Such traffic will increase significantly the
frequency of switches between queues, which may cause the nonpriority queues to lose their bandwidth.
Therefore, when configuring a VC to more than OC-6, it is recommended to limit the high priority traffic
using the
police
command.
SUMMARY STEPS
Use either
Step 5
,
Step 6
,
Step 7
or
Step 8
depending on the desired shaping.
1.
enable
2.
configure
terminal
3.
interface atm
slot/port.subinterface
4.
pvc
vpi/vci
5.
cbr
pcr
6.
vbr-rt
pcr scr
7.
vbr-nrt
pcr scr
8.
ubr
pcr
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Router> enable
Enables privileged EXEC mode.
•
Enter your password if prompted.
Step 2
configure terminal
Example:
Router# configure terminal
Enters global configuration mode.
Step 3
interface atm
slot/port
.subinterface
Example:
Router(config)# interface atm1/0.2
Specifies an ATM interface or subinterface to configure.
Configure subinterfaces so that you can take advantage of
access list definitions for the IP traffic.