Express Route - Private and Microsoft peering

Hi Kapil, Thank you for your suggestion. Each DC has one ER from different provider via different paths (one thru NY and another thru DC). Both DC users hit same VNET/public services and I'll use route-maps to manipulate advertisement so it will be redundant. Based on below diagram, recommendation seems like establishing one private and one public peer from DC1 (as ER comes with 2 physical links - one sub interface for private and another for Public) and same from DC2. Can you please clarify on this? Thank you,

@msheik24 ,

Thanks for sharing your architecture.

When you have 2 ExpressRoute Circuits, from 2 different Service Providers,

• The choice is really up to you.
• A single Physical Connection can have maximum of 2 Peerings (MS and Private)
• As I mentioned earlier, a single ExpressRoute Circuit from a Service Provider is capable of providing 2 Physical Connections. (from ISP end to Azure end)
  • 
  • The above is recommended and used in majority of the cases.
  • This uses 2 Peerings per Physical connection - so totally 4 Peerings.
  • And if one Physical Connection fails, you still have 2 Peerings (one MS and one Private)

In your scenario,

• When you have 2 ExpressRoute Circuits from 2 Service Providers, basically you have 4 Physical Connections. (2 through NY and 2 through DC)
  • This means, you can use 1 Peering per Physical connection - again, totally 4 Peerings like above.
  • The difference is that if one Physical Connection fails (say the one with MS Peering), you will have 3 Peerings left (one MS and two Private)
• In both the cases, you have redundant connectivity and traffic should flow despite a single Physical Connection failing.

Thanks,

Kapil

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Hi Kapil, great info. Thanks for all your time and details. based on your insight and info from community, DC1- ER: primary L2 physical connection will have 2peerings (Private, public) via subinterfaces and use for production related traffic.. Secondary L2 physical connection will also have 2 peerings but recommended to use for non-prod/test related activity so that the bandwidth is available as backup. Same goes with DC2. In total 8 peering with 4 active and rest for non-critical/light traffic. Thanks again for all your help.