Solved: Same AS but different public per each country

syjeon · ‎01-28-2015

Hi,

I'm wondering if we can use same BGP ASN per each own country, but different public block from there on internet, for example.

country a --> BGN ASN 100, public ip range 1.1.1.0/24

country b --> BGP ASN 100, public ip range 1.1.2.0/24

country c --> BGP ASN 100, public ip range 1.1.3.0/24

could it be possible? In general, I thought that it needs to use different ASN per each country due to its own public IP space.

if we can use same ASN, then could it be ok to process routing via BGP?

Thanks.

rais · ‎01-29-2015

It's perfectly fine to use the same AS in multiple countries/continents.

AS is assigned to an Autonomous Entity. If the single network extends into multiple countries or continents it can still use the same ASN. It depends upon your network design and needs if you want to do it or not.

The same goes true for IP addresses. For example a DNS anycast address.

HTH.

View solution in original post

Reza Sharifi · ‎01-29-2015

Hi,

You can use the same AS number in 2 different locations but the IP segment for each location needs to be different.

So, if the 2 IP segments you are referring were public IP segments (the ones you listed above are private) you can not advertise 10.10.10.0/24 in location- A as it is already part of location-B.

but you can advertise these:

A continent : BGP AS 1 , advertising 10.10.10.0/24 - Main datacenter.

B continent : BGP AS 1 , advertising 10.10.11.0/24 - Back datacenter

HTH

View solution in original post

rais · ‎01-29-2015

It's perfectly fine to use the same AS in multiple countries/continents.

AS is assigned to an Autonomous Entity. If the single network extends into multiple countries or continents it can still use the same ASN. It depends upon your network design and needs if you want to do it or not.

The same goes true for IP addresses. For example a DNS anycast address.

HTH.

syjeon · ‎01-29-2015

OK, thanks for your clarification. can I put one more question?

Can we design BGP like below for multi-continents?

A continent : BGP AS 1 , advertising 10.10.10.0/24 - Main datacenter.

B continent : BGP AS 1 , advertising 10.10.10.0/23 - Back datacenter.

So, A,B continent is advertising the routing block like above, in normal situation, the traffic heads to A continent since the routing block is more specific. but, If A continent is having a problem, then, Would it traffic re-route B continent? B continent is not working in normal situation. So, I would like to know if above case is working in case of DR situation.

Reza Sharifi · ‎01-29-2015

Hi,

You can use the same AS number in 2 different locations but the IP segment for each location needs to be different.

So, if the 2 IP segments you are referring were public IP segments (the ones you listed above are private) you can not advertise 10.10.10.0/24 in location- A as it is already part of location-B.

but you can advertise these:

A continent : BGP AS 1 , advertising 10.10.10.0/24 - Main datacenter.

B continent : BGP AS 1 , advertising 10.10.11.0/24 - Back datacenter

HTH

Reza Sharifi · ‎01-29-2015

And one more thing I forgot to note in the last post.

If you are advertising the same ASN from 2 different locations, you need to talk to your providers so they can configure as-override on their sides.

HTH