Clarify network costs between EC2 and ALB/CLB (when free vs $0.01/GB)

[benbridts]

I think that there's a mistake in https://github.com/open-guides/og-aws/raw/master/figures/aws-data-transfer-costs.png

It indicates that cross-AZ traffic between ALB/CLB and EC2 is $0.01/GB, but I think it should be 0 (at least for the CLB)

From http://docs.aws.amazon.com/elasticloadbalancing/latest/classic/enable-disable-crosszone-lb.html:

When you enable cross-zone load balancing, you are not charged for data transfer between the load balancer nodes and the instances

I couldn't find the same kind of clear language in the ALB docs though

[jlevy]

Thanks for the catch. That quote does indicate you are not charged for traffic between EC2 and CLBs some of the time.

On the other hand, the EC2 pricing page suggests it is $.01 outbound:
https://aws.amazon.com/ec2/pricing/on-demand/
https://files.slack.com/files-pri/T2JBBNK18-F2Z7NJEJU/pasted_image_at_2016_11_08_10_05_am.png

Based on that, it sounds like it may be $.01 when cross-zone load balancing is off, and 0 when it is on. We should confirm this, and also confirm what ALB costs really are.

Anyone have confirmed info here?

[rjhintz]

Posted a question on the AWS forums, Application Load Balancer: Charge for data transfer cross zone?

[ThanosBaskous]

Thanks for posting the question, @rjhintz - will keep an eye on the post for answers.

[rjhintz]

Just to note that I bumped this in the forums some time ago, but still no answer.

[rjhintz]

Still no official answer in the forum, though someone remarked that:

this has been answered in the LB deep dive session at re:Invent:

https://www.youtube.com/watch?v=qy7zNaDTYGQ

The answer was "no, no charge for cross-AZ traffic sent by ALBs"

[quinnypig]

Are we willing to accept "no charge for cross-AZ traffic sent by ALBs" is canonically correct, or should I corner an AWS employee at this week's Summit?

[rjhintz]

They said in the forums they'd answer there. We got an indirect answer at Re:invent, but not in the forums, although I bumped it once or twice. Why can't they give us a definitive answer in the forums AWS has established for this sort of clarification or by changing the docs? Rich +1.510.984.2571

…

On Apr 15, 2017 2:28 AM, "Corey Quinn" ***@***.***> wrote: Are we willing to accept "no charge for cross-AZ traffic sent by ALBs" is canonically correct, or should I corner an AWS employee at this week's Summit? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#300 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AACx_JcXY94ZsrpJsIih3t5XCo3QZuVHks5rwCtcgaJpZM4KsmUb> .

[quinnypig]

Terrific question. Time to shake the bushes...