10-07-2015 08:34 AM - edited 03-05-2019 02:28 AM
Should bandwidth match between every two router interfaces connected to each other?
And BANDWIDTH is NOT the same as the "fastEthernet, GigabitEthernet, etc..." funtionality correct?
10-07-2015 08:59 AM
the bandwidth statement is for IGP protocols such as eigrp or ospf , they use them to calculate the metric of the best path for your traffic so yes your right it is irrespective of the physical speed of the interface but is highly recommended due to the fact it calculates metrics and as well you may have issue with tcp packets if its not set to the line speed that you actually have i.e 20mb ISP circuit so you set your bandwidth to 20000 , if the links are the links are point to point then the statements would match but in the real world they hardly ever are , so could be different at either end
10-07-2015 09:01 AM
thanks Mark!
10-07-2015 10:27 AM
To add on to Mark's answer, QoS also relies on the bandwidth statements, especially if you are using the "bandwidth percent" and/or the "bandwidth remaining percent" structures.
10-07-2015 09:23 PM
Addition to mark and trifink valuable posts, the value you configure with the bandwidth command is not what is displayed by the show interface command. The value you configure is that to be used in IGRP updates and also used in computing load.
10-08-2015 07:32 AM
You are asking in community with no relationship to the topic. You are lucky as other CSC member has answered despite of it. Unfortunately, their time will be wasted if future users with same question will not find the answer.
So please use blue [ EDIT ] button to move this thread to Network Infrastructure -> Other Network Infrastructure Subjects
Also, consider rating of valuable answers. It's way to say "thank you for your valuable response". And it will help others to find valuable answers.
Thank you.
10-08-2015 06:06 PM
Hello,
Cisco switches and routers and many other devices use auto-negotiation on each interface. When you connect two devices, both devices on each link send auto negotiation messages to each other to match their speeds. They finally work with the highest speed that both match. For example, if you connect a 10/100 interface to a 10/100/1000 interface, they will agree on100.
Bandwidth command does not have anything to do with interface speed. It is used by routing protocols to find the best path.
Hope it helps,
Masoud
10-08-2015 06:06 PM
thanks Masoud!
10-08-2015 06:40 PM
You are most welcome.
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