Quick Tip: Media Bypass Not Available for Edge Connected Users

This is just a quick tip from the field. If you are deploying media bypass it is important to know it will only be available for endpoints that have registered internally, NOT through the Edge. This is by design and may be changed in the future as can be seen in the cmdlet parameters for New-CSNetworkMediaBypassConfiguration. The parameter ExsternalBypassMode is reserved for future use.

This is important for two reasons:

1. Do not design your solution to plan for media bypass with edge connected users. For example, if you have a branch site with a local gateway but want the users to send Lync traffic over the edge, while maintaining local PSTN breakout through media bypass.

2. If your endpoints can resolve and connect to the Edge, they may do that! Keep in mind that a roaming device such as a laptop stores the last server it connected to in its EndpointConfigurationCache file and will attempt to connect to that server upon the next start. In my scenario we plugged a device in to the internal network, but it still connected to the Edge, the result was media bypass was not working.

Plain and simple, Edge Connected endpoints will not send a bypass-ID in the SDP, so there is absolutely no way to work around it.



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    Posted on by Randy Wintle in Uncategorized 2 Comments

    2 Responses to Quick Tip: Media Bypass Not Available for Edge Connected Users

    1. Ken Lasko

      Interesting find. I wonder what how media bypass will work with edge connected users? Maybe Lync will be able to do media bypass from edge direct to PSTN gateway, instead of going through mediation server? I can’t imagine many scenarios where media bypass would work from an external user direct to an internal PSTN gateway.


      • Randy Wintle

        Well in my scenario we actually had a gateway on the branch site subnet where these users were. However, they were a Site to Site VPN back to the Data Center, and we didn’t want to send media over that tunnel. So in theory, if the client just sent the bypass ID from that subnet, it would match the bypass ID of the local gateway and be able to send traffic to it. But it looks like no bypass ID is generated if you are edge connected.

        I see a handful of customers trying to move to internet only in branch locations, but some of them still need local PSTN breakouts for various reasons.


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