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RandallHolman-1044 asked ChaitanyaNaykodiMSFT-9638 commented

ExpressRoute - Using up to two times the bandwidth limit

The ExpressRoute FAQs state "you may use up to two times the bandwidth limit you procured by using the bandwidth available on the secondary connection of your ExpressRoute circuit." My question is, does this apply to the ExpressRoute Gateway as well?

Say I have a 2G ExpressRoute service (Primary circuit having 2G bandwidth, and Secondary circuit having 2G). I have a VNet associated with a 2G ExpressRoute (2G SKU) Gateway. If I send a 2G data stream over the Primary while simultaneously sending a 2G data stream across the Secondary, will the ER Gateway support both simultaneous streams (e.g. 4G aggregate), or will one of the 2G streams get dropped?

azure-expressroute
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1 Answer

ChaitanyaNaykodiMSFT-9638 avatar image
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ChaitanyaNaykodiMSFT-9638 answered ChaitanyaNaykodiMSFT-9638 commented

Hello @RandallHolman-1044, Welcome to the Microsoft Q&A forum.

Based on your questions above.

The ExpressRoute FAQs state "you may use up to two times the bandwidth limit you procured by using the bandwidth available on the secondary connection of your ExpressRoute circuit." My question is, does this apply to the ExpressRoute Gateway as well?

No, it does not apply to ExpressRoute Gateway. From the FAQ you referenced above there is an additional statement which states If traffic flows through an ExpressRoute Gateway, the bandwidth for the Gateway SKU is fixed and not burstable.

Say I have a 2G ExpressRoute service (Primary circuit having 2G bandwidth, and Secondary circuit having 2G). I have a VNet associated with a 2G ExpressRoute (2G SKU) Gateway. If I send a 2G data stream over the Primary while simultaneously sending a 2G data stream across the Secondary, will the ER Gateway support both simultaneous streams (e.g. 4G aggregate), or will one of the 2G streams get dropped?

From the statement above the bandwidth for the Gateway SKU is fixed and not burstable this statement is true because from this documentation when you deploy an ExpressRoute Gateway, gateway VMs are deployed to the gateway subnet and configured with the required ExpressRoute gateway settings. These VM's determine the bandwidth provided by the Express-Route Gateway SKU's (in your case it is 2G) as per their hardware limitations. So, in your scenario the ExpressRoute gateway will be able to handle 2G bandwidth as promised but does not guarantee if any additional bandwidth can be handled and might result in packet drops. The recommended resolution in this scenario is to upgrade your Gateway SKU to accommodate additional bandwidth.

Hope this helps! Please let me know if you have any additional questions. Thank you!


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Thank you for the response, much appreciated. Just so I'm clear, if I have a 10G ExpressRoute Service, and I send 10G of traffic simultaneously across both Primary & Secondary, and I have a 10G ER Gateway, the gateway would not actually support the two (2) 10G data streams - it would only be able to support one 10G data stream at a time (and drop the other).

I'm just trying to establish if the ER Gateway bandwidth is the total bandwidth available for both Pri & Sec combined (i.e. I may be trying to send a combined total of 2x10G, but the gateway is actually limiting to 1x10G), or if the Pri & Sec will have their own b/w on the gateway (send combined total of 2x10G, and the gateway will handle 2x10G data stream).

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Hello @RandallHolman-1044,

it would only be able to support one 10G data stream at a time (and drop the other)

Yes, your understanding here is correct. You can try exploring ExpressRoute FastPath for this scenario.
Hope this helps! Please let me know if you have any additional questions. Thank you!


Please "Accept the answer" if the information helped you. This will help us and others in the community as well.


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