SD-WAN and Dropped Calls

[Alex Pfeil]

I was wondering if somebody could share their experience with SD-WAN.  Has SD-WAN eliminated dropped calls in your network? Please comment on which Cisco SD-WAN solution you are using as well. Thank you for your response in advance.

[Eugene Khabarov]

Hi Alex, I would say opposite, but unfortunately SD-WAN is not "magic pill" or "make-it-all-good button" that makes your network better without proper planning. E.g. if you have just one link in the remote office where you were experiencing VoIP call issues, SD-WAN won't solve it obviously. Same applicable if you have two uplinks with equally bad quality, BUT if you properly plan and implement App Aware routing with former Viptela products, it can greatly help during intermittent problems with specific uplink in a such way that your users won't even notice outage.

[Alex Pfeil]

We have 2 circuits at a branch, internet and MPLS. We understand that call quality may not be as good as the MPLS. However, we would like to know if SD-WAN would eliminate lost calls if the MPLS circuit failed. Would the failure be noticed sub-second, and the voice traffic be re-routed over the internet circuit so that it would not fail?

[Eugene Khabarov]

Failure won'be noticed if fail-over happens within subsecond interval and BFD can be configured to support even 100 ms fail-over, but please be accurate with this to avoid excessive flapping:

https://sdwan-docs.cisco.com/Product_Documentation/vManage_Help/Release_18.3/Configuration/Templates/BFD

[Alex Pfeil]

What if the failure is upstream in the SP and not directly on the link?