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Alternates
TANDBERG VIDEO COMMUNICATIONS SERVER ADMINISTRATOR GUIDE
About Alternates |
| Configuring Alternates |
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The purpose of an Alternate is to provide extra reliability in the rare case that a VCS fails.
Each VCS can be part of a pool of up to 6 Alternate VCSs that act as backups to each other in case one becomes unavailable (for example, due to a network or power outage).
All the Alternates in a pool are configured similarly and share responsibility for their H.323 endpoint community. When an H.323 endpoint registers with the VCS, it is given the IP addresses of all the VCS’s Alternates. If the endpoint loses contact with the initial VCS, it will seek to register with one of the Alternates. This may result in your H.323 endpoint community’s registrations being spread over all the Alternates.
When the VCS receives a Location Request, it checks its own registration database along with that of each of its Alternates before responding. This allows the pool of endpoints to be treated as if they were registered with a single VCS.
You must configure all Alternates in a ! pool identically for all registration and call features such as authentication,
bandwidth control and policy. If you do not do this, endpoint behavior will vary unpredictably depending on which Alternate it is currently registered with. Alternates should also be deployed on the same LAN as each other so that they may be configured with the same routing information such as local domain names and local domain subnet masks.
Alternates are not used to increase the
capacity of your network; they are to provide redundancy. To increase
capacity, add one or more additional VCSs to your network and neighbor them together.
Alternates are periodically interrogated
to ensure that they are still functioning. In order to prevent delays during call
setup, any
If you have Alternates configured, you
should change the registration Time to live on the primary VCS and on each of
its alternates from the default 30 minutes to just a few minutes. This setting determines how often endpoints are required to
When configuring your VCS with the
details of the system it will be using as a traversal server, you are given the
opportunity to include details of any Alternates of that traversal server. Adding this information to your VCS will ensure that, if the original traversal server becomes unavailable, your VCS can use one of its Alternates instead.
Each VCS can be configured with the IP addresses of up to five other VCSs that will act as Alternates should the current VCS become unavailable.
To configure Alternate VCSs:
•VCS Configuration > Alternates.
You will be taken to the Alternates page.
•xConfiguration Alternates
! | Systems that are configured as |
| Failover |
Alternates must not be configured as |
| applies to H.323 | |
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| neighbors to each other. |
| SIP currently has no equivalent. |
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Save | Alternate 1 to Alternate 5 IP address |
Click Save to save your | To configure another VCS as an Alternate, enter its IP address. |
changes. | Up to 5 Alternates may be configured. |
Introduction | Getting Started |
| Overview and |
| System |
| VCS | Zones and | Call |
| Bandwidth |
| Firewall |
| Maintenance |
| Appendices |
| Status |
| Configuration |
| Configuration | Neighbors | Processing |
| Control |
| Traversal |
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D14049.03 |
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MAY 2008 |
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