Configuring the Interface Bandwidth
By default, the Junos OS uses the physical interface’s speed for the MIB-II object, ifSpeed. You can configure the logical unit to populate the ifSpeed variable by configuring a bandwidth value for the logical interface. The bandwidth statement sets an informational-only parameter; you cannot adjust the actual bandwidth of an interface with this statement.
 | Note: We recommend that you be careful when setting this value. Any interface bandwidth value that you configure using the bandwidth statement affects how the interface cost is calculated for a dynamic routing protocol, such as OSPF. By default, the interface cost for a dynamic routing protocol is calculated using the following formula: cost = reference-bandwidth/bandwidth, where bandwidth is the physical interface speed. However, if you specify a value for bandwidth using the bandwidth statement, that value is used to calculate the interface cost, rather than the actual physical interface bandwidth. |
To configure the bandwidth value for a logical interface, include the bandwidth statement:
You can include this statement at the following hierarchy levels:
- [edit interfaces interface-name unit logical-unit-number]
- [edit logical-systems logical-system-name interfaces interface-name unit logical-unit-number]
rate is the peak rate, in bps or cps. You can specify a value in bits per second either as a complete decimal number or as a decimal number followed by the abbreviation k (1000), m (1,000,000), or g (1,000,000,000). You can also specify a value in cells per second by entering a decimal number followed by the abbreviation c; values expressed in cells per second are converted to bits per second using the formula 1 cps = 384 bps. The value can be any positive integer. The bandwidth statement is valid for all logical interfaces, except multilink interfaces.
