ASN number 65515 in the BGP advertisement for the VNet IP space towards the Expressroute peers

Question

When I checked the BGP table for the express route circuit, I see that I have the local ones (for the linked VNet IP space) has the ASN of 65515. Is it a hardcoded value just like 12076? I see that the ASN got removed when advertised to SP.
Thanks,
Difan

Answer 1

@Difan Zhao Thank you for reaching out to Microsoft Q&A. I understand that you are having questions regarding BGP ASN 65515 with respect to Express Route circuit.

"Microsoft uses AS 12076 for Azure public, Azure private and Microsoft peering. We have reserved ASNs from 65515 to 65520 for internal use. Both 16 and 32 bit AS numbers are supported."

Since this ASN is for internal use, it will be removed during re-advertisement of Azure routes. Hope this helps.

Please let us know if you have any further questions and we will be glad to assist you further. Thank you!

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