BGP Communities Explained

Lessons Discussion
#85

Hi
Well know has 4 types and all clear

There is another type called private community and has 2 type
Standard and extended

I am talking about this one which you can use it to manipulate as path prepend
Which type this? Is it standard?

#86

Hello Ali

I see, you’re talking about the two different types of BGP communities, the standard and extended communities. These are two different ways of representing communities. The standard BGP community is defined by a 32-bit number that can be included with a route within the BGP update. A community is actually an optional transitive attribute.

Now an extended BGP community is simply a redefining of the BGP header that allows a 64-bit number to represent the community rather than a 32-bit number. This simply gives more granularity to the configuration of various attributes. In particular, extended BGP communities provide structure for various classes of information and are very often used for VPN services. The extended communities format is explained in detail in RFC 4360.

Now this should not be confused with a Private BGP community. Private BGP communities follow the convention that the first 16-bits represent the AS of the community origination, and the second 16-bits represent a pattern defined by the originating AS. The private BGP community pattern could vary from organization to organization, do not need to be registered or published. That’s the meaning of the word “private” in the title.

You can find more info about all of these at the following links:

I hope this has been helpful!

Laz

#87

@ReneMolenaar : Thanks for this amazing BGP community explanation which I have had used for troubleshooting. I have a question here.
Is there a possibility for any customer to present with their communities like : and ask to add this is within t he BGP communities.
I have had checked the community examples that you have shared with specific like Prepending/Regional/Local pref
but not able to wrap my head around the customer ASN number for specific customer.

#88

Hello Rinat

From what I understand, you’re asking if you as a customer can create your own community and share it with the ISP? I’m not sure I understand your question. Can you share a little bit more and clarify so that we can help you further?

Thanks!

Laz

#89

the link is broken BGP Community No Advertise

#90

Hello Konstantinos

I think it’s OK now:

Thanks!

Laz