1. Ability to maintain local media coverage among Teams clients and the SBC. This is commonly referred to as “Media Bypass".
The Media Bypass is essential for reducing call setup time, providing a higher level of reliability by eliminating the need for media to flow to Cloud Microsoft and back, and thus ensure the best possible call quality. This was resolved in mid-2019 when Microsoft released the feature Media Bypass which we briefly explain in our previous article.
However, Media Bypass requires that the public IP address of the SBC Teams be available to clients. What happens if the client Teams is on the internal network (has a private IP address)? It is not always possible to access the public IP address of the SBC from the company’s internal network.
2. To resolve the issue where the public IP address of the SBC is not available to Teams clients, Microsoft has developed a technology called “Local Media Optimization (patent pending).”
Local media optimisation is useful in two cases.
Case 1.
The client is on an internal network and wants to use media bypass but cannot access the public IP address of the SBC. The desired result is for the client to use the private IP address SBC instead of the public one (192.168.5.5 in the image below)
Local Media Optimization selects the optimal IP address for the SBC, based on the client's location Teams , and provides it to the client via the SDP (Session Description Protocol).
Note: You must ensure that the SBC Local Media Optimization technology is supported. A list of SBC devices that support the technology, along with instructions, can be found on this page https://docs.microsoft.com/en-us/MicrosoftTeams/direct-routing-media-optimization-configure#configure-sbcs-for-local-media- optimization according to the provider’s specifications sbc
What is "optimal IP"?
If the client is on the internal network, Local Media Optimization detects the client's location and provides the client's internal IP address SBC. If the client is outside the corporate network, the technology also detects this and provides the external or public IP address of the SBC.
To understand whether the user is in the internal network or not, the system uses external addresses Trusted IP addresses of each registered branch office.
What is "Trusted IP"?
These IP addresses are the IP addresses used by Microsoft Teams clients when they connect to Microsoft 365. When the Teams client connects to Microsoft 365, its IP address is compared to the list of trusted IP addresses. If a match is found, the user’s location is marked as internal. You must add these external IP addresses for each site where you have users using Local Media Optimization. Please read our detailed documentation ( https://docs.microsoft.com/en-us/MicrosoftTeams/direct-routing-media-optimization ) to see how this works.
Case 2.
A company must use a SBC that is inaccessible via the Microsoft interface Direct Routing. Common scenario—it is not possible to provide a publicly routable IP address for the SBC at selected corporate locations.
In the image below, the SBC in Vietnam cannot have a public IP address for direct interaction with the Microsoft interface Direct Routing. However, the SBC one in Singapore (which is also accessible via the internal network in SBC in Vietnam) can.
In this case, with the help of Local Media Optimization, we can still connect to SBC Vietnam “virtually.” This means that even though Microsoft doesn’t have direct access to it, the tenant administrator can pair it and specify that to send a call to SBC in Vietnam, we must go through the SBC in Singapore from the Direct Routing.
With local media optimization, we can detect the customer's location and provide the IP address of the SBC based on the user’s location. There are two modes for this scenario.
Ways of optimising local media
Always bypass mode
This mode is intended for situations where the internal network is fully routable.
In this case, if the user is located on an internal network, Local Media Optimization always returns the internal IP address of the SBC. See the image below for reference; a user might be at a German site or traveling in France.
Local users only" mode
By setting this mode, the tenant administrator indicates to Local Media Optimization that the network is not fully routable.
In the photo below, a customer Teams in Indonesia does not have direct access to the network segment in Vietnam. The customer’s traffic will be routed via the SBC in Singapore, which has access to both locations.
You can find suppliers and models of Session Border Controler (SBC), which support local media optimization, as well as configuration documentation on this page:https://docs.microsoft.com/en-us/MicrosoftTeams/direct-routing-media-optimization We agree: Microsoft is a great choice for companies looking to migrate their phone systems to Microsoft Teams Direct Routing !
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