Hello Shaan
Yes, that is correct. Remember that the reference bandwidth only applies to the calculations made locally on the router. Other routers, when they calculate their own metrics to destinations, will use whatever reference bandwidth is configured locally. For this reason, it is important to verify that the same reference bandwidth is used on all OSPF routers in your topology.
I hope this has been helpful!
Laz
Thank You Lazaros
Regards
Shaan
Hi,
It would be great if you tell what is updated ?
Thanks
Hello Sims
Do you mean you’d like to keep track of what lessons have been updated recently? If that is the case, let me know and I can inform Rene.
Laz
I mean It would be helpful , if you can tell what update or changes has been made and why
Thanks
Hello Sims
I assume you mean updates or changes made to the content of the lessons themselves, correct? I’ll let Rene know of this suggestion. Thanks for your feedback, it’s always useful and helpful!
Laz
Hello @sims,
I agree, that would be useful. We did an attempt with this page:
This page is automatically updated but it also happens when we save a lesson after editing a single typo. A “changelog” that shows what and when something is edited would be convenient. I’ll add it to my list and give it some more thought.
Rene
hi all, great to be here, and this is my first post/reply. 
In the article, the particular line “Let’s set it to 1.000 Mbps”, I presume we should change it to 1,000 instead?
Thanks for your time and will continue to support this site.
Hello Chin
Yes, you are correct, I will let Rene know to make the modifications.
Thanks for pointing that out!
Laz
Hey All,
I know that Cisco warns you quite clearly when you change the reference-bw locally on a router to perform this task on all routers.
However, what is the worst-case scenario if this is not done? Is it just that you will end up with sub-optimal routing due to some links being costed differently on routers?
Hello Sebastian
Suboptimal routing is definitely a result of inconsistent reference bandwidths. The worst-case scenario I would say is that you would have an OSPF routing loop which is much more devastating than suboptimal routing.
Remember that OSPF is a link-state routing protocol, which means that each OSPF router has a complete picture of the whole network found within its link-state database. This means there must be consistency across all routers.
If that consistency is not achieved, the results can indeed be quite unpredictable, ranging from suboptimal routing to routing loops, to routing black holes.
I hope this has been helpful!
Laz
show ip protocols | include Reference is not working either. But show ip ospf | include band works fine for me.
Hello Yannick
Remember that the show ip protocols | include Reference command is simply looking for the text “Reference” in the output and displays only those lines containing that text. From platform to platform and from IOS to IOS, Cisco may slightly change the syntax of the output, resulting in a change in whether or not that command works.
I suggest you take a look at the output of the show ip protocols command and the show ip ospf command and check to see which command includes the information you want. Then make a note of some of the text found on that particular line of output, and include that after the include keyword. That way you can be sure that the information you want will appear in the output of the command.
I hope this has been helpful!
Laz
The serial interface has a bandwidth of 1.544 kbps (1.5 Mbps) and a cost of 64. It was calculated like this:
100.000 kbps reference bandwidth / 1.544 kbps interface bandwidth = 64,76
Is it correct to use 1,544kbps or is 1.544kbps correct? same for 100.000kbps.
Hello Bryan
I think there is a little bit of confusion as to the use of either “.” or “,” as the decimal point and as the thousands separator. It seems that Rene used both systems interchangeably in this lesson and that has caused confusion.
In some countries of the world, a “full stop” or “.” is used as the decimal point while a comma “,” is used as the thousands separator. So a value of one thousand five hundred and three point seven would be written out as 1,503.7.
In other parts of the world, the “.” and “,” are interchanged, so the same number would be written out as 1.503,7. For more info on this, take a look at this article:
From here on in, I will be using the “.” as the decimal point and the “,” as the thousands separator.
Now on to your question. I will write out the text correctly below:
The serial interface has a bandwidth of 1,544 kbps (1.5 Mbps) and a cost of 64. It was calculated like this:
100,000 kbps reference bandwidth / 1,544 kbps interface bandwidth = 64.76
So which is correct? It depends upon the standards in your country, however, I will ask Rene to make the changes to make the values consistent within the lesson.
Thanks for pointing this out!
Laz