Traffic Load distribution on ISN transports

SIMMN · ‎11-01-2022

I think I would need some suggestions.

I have a customer looking for ACI multi-site to refresh their two existing DCs in a multi-year road map. The two DCs are inter-connected with two dark fibre transports and have eBGP peering on top. One of the requirements and current setup they have is to steer specific application, such as SQL, traffic between DCs over the dark fibre #1 and rest of the inter-DC application traffic to dark fibre #2.

Considering the ACI Multi-Site ISN, the underlay using the two dark fibre transports would load balance/ECMP automatically. I think the same for VXLAN overlay from the load balancing or load sharing perspective between two DCs? I could be wrong but I do not think ISN overlay has the capability/functionality to steer specific application/EPG traffic to one individual transport, right? Any further suggestion?

Thanks!

Sergiu.Daniluk · ‎11-02-2022

First, what do you mean by "rest of the inter-DC traffic"? "Application traffic" is clear - traffic between EPs behind ACI, but not sure what you mean by "rest of the traffic".

Sergiu

SIMMN · ‎11-02-2022

The post has been updated for clearity. What I mean in their current setup, the SQL traffic between DCs for example is using dark fibre #1 and other application traffic between DCs use dark fibre #2.

Sergiu.Daniluk · ‎11-02-2022

Ah ok. Got it. So all traffic is between EPs behind ACI fabrics. I am afraid there is hardly any way to bypass ECMP, however, what you can do which can alleviate the pain is use QoS: set a CoS for the specific EPG where SQL traffic is present, preserve the QoS level in ISN, and on ISN routers you allocate desired bandwidth for the SQL traffic.

I hope that would help.

Cheers,

Sergiu

SIMMN · ‎11-03-2022

Yeah, thought so. QoS might be the only way to help “guarantee” the bandwidth wanted by specific applications. But if i implemented QoS, wouldn’t it only affect the overlay VXLAN traffic which is transparent to the underlay ISN devices? Do I have to do specific configuration on ISN to preserve the marking or honor the class?