Bandwidth command

datchchadatchcha Member Posts: 265
in CCNA & CCENT
When you set the bandwidth on a Interface, which is in kilobites I belive. Is this kilobites per second or does it relate to the maxium through put of the connection. What is a connection of a T1 converted into kilobites, and does anyone know of a good calculator?


en
config t
int s0
ip address 192.168.1.1 255.255.255.0
no shut
bandwidth 64
clock rate 64000
Arrakis
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  • NetstudentNetstudent Member Posts: 1,693 ■■■□□□□□□□
    a T1 is 1.544 Mb/s so thats 1,544 Kb/s. You really don't needa calculator. All you have to know is that Kilo is 1000bits, mega is 1,000,000bits and giga 1,000,000,000 bits

    The bandwidth parameter has nothing to do with throughput. It is an arbitrary number that is used in routing protocol calculations.

    It may also be important to note that OSPF divides that arbitrary number into 100,000,000 to calculate its metric.
    .
    So if you had a partial T1 with 1Mb of bandwidth, the logic can't assume that you are only using a partial T1, it will assume you are using a full T1. So the calculation would be 100,000,000/1,544,000 which would give you the default ospf cost for a T1 link. 64!!!!!
    There is no place like 127.0.0.1 BUT 209.62.5.3 is my 127.0.0.1 away from 127.0.0.1!
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  • datchchadatchcha Member Posts: 265
    Netstudent wrote:
    a T1 is 1.544 Mb/s so thats 1,544 Kb/s. You really don't needa calculator. All you have to know is that Kilo is 1000bits, mega is 1,000,000bits and giga 1,000,000,000 bits

    The bandwidth parameter has nothing to do with throughput. It is an arbitrary number that is used in routing protocol calculations.

    It may also be important to note that OSPF divides that arbitrary number into 100,000,000 to calculate its metric.
    .
    So if you had a partial T1 with 1Mb of bandwidth, the logic can't assume that you are only using a partial T1, it will assume you are using a full T1. So the calculation would be 100,000,000/1,544,000 which would give you the default ospf cost for a T1 link. 64!!!!!

    So in order for my T1 to be used with the curret Metric for IGRP, EIGRP and OSPF i need to use the following command? Is the 1544 correct? 64 would have it marked as ISDN right ?

    bandwidth 1544

    thank you
    Arrakis
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  • networker050184networker050184 Mod Posts: 11,962 Mod
    The default is a T1 so you don't need the bandwidth statement.
    An expert is a man who has made all the mistakes which can be made.
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  • datchchadatchcha Member Posts: 265
    networker050184 wrote:
    The default is a T1 so you don't need the bandwidth statement.

    I understand, but lets say i wanted to set it, so it is displayed in the running configure and/or startup config
    Arrakis
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  • networker050184networker050184 Mod Posts: 11,962 Mod
    You are correct it would be bandwidth 1544 if you want to put it on there.
    An expert is a man who has made all the mistakes which can be made.
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