Access Edge
,The Access Edge role serves as the core of the Edge Server and is responsible for all of the signaling functionality. Without the Access Edge role deployed, the Web Conferencing Edge and A/V Edge roles cannot function. The Access Edge also serves a few distinct purposes including remote access, federation, and Public IM Connectivity.
Remote Access
One function of the Access Edge Server is to provide remote access capabilities to a Lync Server infrastructure. After an internal deployment of pools is complete, an Access Edge Server can be provisioned to enable users to sign in and use their endpoints across the Internet.
As long as the appropriate SRV records exist in DNS or the client is manually configured correctly, a user can travel in and out of the office without ever making a change to an endpoint. This enables users to have full access to their internal features regardless of location.
Note
Access Edge Server traffic is performed using port 443 over TCP, which is the standard for HTTPS traffic. Traffic is rarely blocked or interfered with by any kind of proxy or firewall software.
Federation
The Access Edge Server also provides the capability to federate with other organizations that have deployed Lync Server, meaning the two organizations can communicate with each other as if it were a single deployment.
Users have different feature sets available when using federation, depending on the version of Lync Server a partner has deployed. The feature set is the lowest common denominator between the two organizations. For example, if a partner runs Live Communications Server 2005, only IM and presence will be available. However, if a partner organization is running Office Communications Server 2007 R2, A/V and Desktop Sharing features can be used through federation. The largest feature set is available if both organizations are running Lync Server.
Access Edge Servers use certificates and mutual TLS (MTLS) to secure the SIP signaling used across the Internet with each other. This ensures that instant messaging and presence traffic is completely secure and never transmitted in plain text.
Note
Organizations generally procure a certificate from a public certificate authority so that partners trust their server by default. However, it is possible to exchange certificate chains with a partner to support additional certificate authorities.
Public IM Connectivity
A special form of federation is the capability to use Lync Server to communicate with contacts on the public IM networks, referred to as Public IM Connectivity (PIC). The AOL, Yahoo!, and MSN networks are the native Public IM Connectivity providers to Lync Server. To communicate with these contacts, users simply need to add the address to a contact list.
Caution
Although it is possible to federate with Google Talk contacts, this capability is not native to the Access Edge Server role. To federate with Google Talk, an organization must deploy the XMPP Gateway Server role, which was software introduced for Office Communications Server 2007 R2. There is no equivalent or updated product for Lync Server at this time.
Lync Server users can see presence and exchange instant messages with their contacts when Public IM Connectivity is provisioned. The conversations are limited to peer-to-peer, though, and they cannot include three or more participants as users are accustomed to within the organization or with federated contacts.
Audio and video support with the MSN or Windows Live networks is a new feature in Lync Server. The A/V conversations are performed using the same RTAudio and RTVideo codecs native to both platforms, but are also limited to two-party calls.
Tip
With Microsoft Xbox Kinect and Xbox Live service, it’s possible to conduct a video conversation with an MSN user viewing a Lync Server user on his or her television at home or work, as shown in Figure 6.2. This functionality will be delivered in a future update to the Kinect software.
Figure 6.2 Xbox Kinect Video Calls with Lync Server
As of this writing, only the Yahoo! network requires additional licensing, which is done on a per-user monthly subscription fee. As long as users have a Lync Server Standard CAL, the AOL and MSN Public IM Connectivity are provided at no extra cost.