This document describes the Bandwidth Throttling feature that lets you control transmit and receive bandwidth on synchronous WAN interfaces and Ethernet interfaces. It has the following sections:
Introduction
Bandwidth Throttling Commands
Introduction
The Bandwidth Throttling feature allows you to control the bandwidth that certain interfaces use to transmit or receive packets. You can set a bandwidth limit that is less than the physical speed of the interface, and you can set a separate receive limit and transmit limit. This lets you provide different levels of bandwidth in a network. For example, an interface may physically have a hardware speed of 2.0 Mbps, but you could configure the router to allow only 256Kbps of transmit or receive bandwidth. The bandwidth limit of 256Kbps becomes the virtual speed of the interface.
The Bandwidth Throttling feature works on Ethernet interfaces and on synchronous WAN interfaces, including T1, E1, or Frame Relay. It does not run on DDS or ISDN interfaces.
Setting Up Bandwidth Throttling
The following steps show how to set both the transmit and receive bandwidth limits.
Serial Config> prompt for the interface on which you want to set the bandwidth limit.
Config>network 2
Circuit Configuration
Circuit Config <NET-2> sl
Serial Line Configuration
Serial Config <WAN2>
Serial Config <WAN2> set hdlc transmit-bandwidth-limit
Transmit Bandwidth Limit, or 0 for no limit [0]?256000
Serial Config <WAN2> set hdlc receive-bandwidth-limit
Receive Bandwidth Limit, or 0 for no limit [0]?56000
Serial Config <WAN2> list
Line Discipline: Sync
Maximum network layer frame size: 2048
Speed (0=not configured): 2048000 bits/sec
HDLC Data encoding: NRZ
HDLC Idle State: Flag
Transmit delay counter: 0 units
Transmit Bandwidth Limit (0=none): 256000 bits/sec
Receive Bandwidth Limit (0=none): 256000 bits/sec
Serial Config <WAN2> exit
Circuit Config <NET-2> exit
Config>
*restart
Are you sure you want to restart the gateway?(Yes or [No]):y
FRMGR<WAN#> prompt.FRMGR <WAN2> list all
.
.
.
Congestion monitoring = Yes CIR monitoring = No
PVCs P1 allowed = 64 Interface MTU in bytes = 2048
Line access rate bps = 256000 CIR monitor adjustment = 1
Timer T1 seconds = 10 Counter N1 increments = 6
..
.
set hdlc transmit-bandwidth-limit [C]
This command is available at the Serial Config <WAN#> prompt.
Sets the transmit limit in bits per second. The default is 0 (zero), which means there is no limit.
set hdlc transmit-bandwidth-limit
Transmit Bandwidth Limit, or 0 for no limit [0]?
Serial Config <WAN#> prompt.Sets the receive limit in bits per second. The default is 0 (zero), which means there is no limit.
set hdlc receive-bandwidth-limit
Receive Bandwidth Limit, or 0 for no limit [0]?
Serial Config <WAN#> prompt. It shows the configuration of your serial interface, including the Receive Bandwidth Limit and the Transmit Bandwidth Limit configured on the interface.
Example: list
Line Discipline: Sync
Maximum network layer frame size: 2048
Speed (0=not configured): 2048000 bits/sec
HDLC Data encoding: NRZ
HDLC Idle State: Flag
Transmit delay counter: 0 units
Transmit Bandwidth Limit (0=none): 256000 bits/sec
Receive Bandwidth Limit (0=none): 256000 bits/sec
Monitor> prompt that relate to Bandwidth Throttling.
List Interface <ifc-number>
The list interface <interface #> command at the Monitor> prompt displays the actual Transmit and Receive Bandwidth Limits configured on the interface.
Self-Test Self-Test Maintenance
Nt Interface Passed Failed Failed
2 PPP/0 0 0 0
Point to Point data-link layer on SCC Serial Line interface
Line Speed: 256000 bps
Adapter cable: V.35 DTE RISC Microcode Revision: 3
V.24 circuit: 105 106 107 108 109 125 141
Nicknames: RTS CTS DSR DTR DCD RI LL
PUB 41450: CA CB CC CD CF CE
State: OFF OFF ON OFF OFF OFF --
Configured Line speed: 2.048 Mbps
Measured Line speed: ~Measurement not available
Transmit Bandwidth Limit: 256.000 Kbps
Receive Bandwidth Limit: 2.048 Mbps
Last port reset: 7 seconds ago
Input frame errors
CRC error 0 alignment (byte length) 0
missed frame 0 too long (> 1552 bytes) 0
aborted frame 0 DMA/FIFO overrun 0
receive bandwidth limit 0
Output frame counters:
DMA/FIFO underrun errors 0 Output aborts sent 0
Note the following information about these statistics and speeds:
The displays shows each interface in the router, as well as each WAN device. WAN devices are displayed as dev:WAN#. A device can have more than one interface.
Device utilization (dev:WAN#) statistics are calculated using all packets, including PPP LCP packets and Frame Relay LMI packets. These statistics are calculated based on packets that are actually transmitted or received over the physical device.
Interface utilization statistics are calculated using only uncompressed data packets. Because the statistics are calculated based on uncompressed data, the interface statistics may add up to more than 100%.
list utilization
Mean Last High Mean Last High
Xmt Xmt Xmt Rcv Rcv Rcv Total Total
Nt Interface Util Util Util Util Util Util Traps Intervals
-- --------- ----- ----- ----- ----- ----- ----- ---------- --------
0 Eth/0 1% 1% 1% 1% 1% 1% 0 295
1 PPP/0 0% 0% 0% 0% 0% 0% 0 295
dev:WAN1 0% 0% 0% 0% 0% 0% 0 295
2 PPP/1 6% 5% 6% 2% 1% 2% 0 296
dev:WAN2 6% 5% 6% 2% 1% 2% 0 296
------Speeds used in bits/second------
Nt Interface Xmt Speed Rcv Speed
-- --------- ------------ ------------
0 Eth/0 10000000 10000000
1 PPP/0 1536000 1536000
2 NULL/1 0 0
3 PPP/1 256000 2062988
Device (dev:WAN#) byte counts do not include CRC bytes and HDLC flags.
PPP LCP or Frame Relay LMI packets are counted at the device level, and not at the interface level.
Interface byte counts do not include the PPP or Frame Relay headers, CRC bytes, and HDLC flags.
list statistics
Nt Interface Unicast Multicast Bytes Packets Bytes
Pkts Rcv Pkts Rcv Received Trans Trans
0 Eth/0 18257 161 7741439 19384 7802844
1 PPP/0 0 0 0 0 0
dev:WAN1 0 0 0 0 0
2 PPP/1 18754 0 7528631 17517 7425724
dev:WAN2 18754 0 7546701 17517 7442838