For Media Bypass to function, the following requirements must be met:
A Mediation Server role is deployed either as a standalone server or collocated on a Front End Server.
Media Bypass must be enabled on a SIP trunk. The centralized media processing option must also be enabled on the trunk.
Media Bypass must be enabled at a global level.
Enable Media Bypass
Media
Bypass must be enabled at a global level before clients attempt to use
the bypass features. When enabling Media Bypass in the Lync Server
infrastructure, an administrator has two options:
Always bypass—
This choice instructs clients to always bypass the Mediation Server
role. This option works only if a trunk configuration also has the
enable media bypass option selected. All Lync clients must have good
network connectivity to the other end of every single SIP trunk for
this option to be effective. This option may make sense in very small
deployments.
Use sites and region configuration—
This choice is a better option when Lync endpoints might not have good
network connectivity to each SIP trunk and enables the network region
and site configuration to limit when Media Bypass is actually used. Enable bypass for non-mapped sites can be selected only if Use sites and region configuration is selected first. This allows for sites and subnets not explicitly configured to use Media Bypass.
Note
If Call Admission Control is also enabled, the only
available option for Media Bypass is to use the network site and region
configuration.
To select a choice in enabling Media Bypass, use the following steps:
1. | Open the Lync Server 2010 Control Panel.
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2. | Click Network Configuration.
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3. | Click Global.
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4. | Highlight the global policy, click Edit, and then select Show Details.
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5. | Check the box Enable media bypass.
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6. | Select either Always bypass or Use sites and region configuration.
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7. | If selecting the Use sites and region configuration, optionally check the box Enable bypass for non-mapped sites.
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8. | Click Commit.
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Site Configuration
For Media Bypass to function properly when sites are
bandwidth-constrained, the appropriate network region and bandwidth
policy profiles must be created. Media Bypass does not use the actual
bandwidth values, but does compare links with a bandwidth value set to
ones without a value. In other words, sites with any bandwidth policy
applied do not use Media Bypass across the link, but sites without a
policy applied attempt to use Media Bypass.
Call Admission Control and Media Bypass
Keep
in mind that although Call Admission Control and Media Bypass use the
same network configuration objects, there are some situations in which
they behave slightly differently. For instance, calls that use Media
Bypass do not have bandwidth policy profiles applied to restrict the
bandwidth used. In other words, calls using Media Bypass do not count
toward the cumulative audio limit or restricted by the audio session
limit. It is assumed in scenarios where Media Bypass is used that no
bandwidth constraint exists.
