Nortel Networks NN43001-121 manual Redundancy with Load Balancers

Load Balancer planning 45

•Every Office Communications Server must have exactly one network adapter. Multihoming an Office Communications Server is not supported. If a 10/100 network adapter does not meet the required bandwidth constraints, a gigabit network adapter must be used.

•The network adapter must have at least one static IP address. This IP address will be used for the incoming load-balanced traffic.

•The computer must have a registered FQDN. The IP address registered for this FQDN must be publicly accessible from within the enterprise.

•The Load Balancer must include less than one gigabit capacity for up to 50 000 concurrent client connections. One gigabit of capacity is required to support more than 50 000 concurrent client connections.

For more information about Load Balancer requirements, see Microsoft Office Communications Server 2007 Document: Planning Guide. Download Microsoft technical documentation from the Download Center at www.microsoft.com.

Redundancy with Load Balancers

You can add redundancy to your network by placing Load Balancers, such as a Nortel Application Switch, between the OCS 2007 Front End servers and Mediation Servers, and between the Mediation Servers and the OCS 2007 Proxy Servers.

The outgoing Load Balancer balances SIP invites from the Mediation Server to the OCS Proxy server. The Mediation Server sends all SIP Invites to the Virtual IP (VIP) of the outgoing Load Balancer. The Load Balancer then sends the SIP Invite to the least busy Office Communications Server 2007 OCS Proxy.

The incoming Load Balancer balances SIP invites from the Mediation Server to the least busy Front End server. This is the same load balancer that is used when the Office Communicator addresses the pool for registration. The OCS Proxy sends all SIP invites to the Virtual IP (VIP) of the incoming Load Balancer.

Redundancy is also ensured for calls to an Office Communicator user by having each OCS Proxy server register to the MCM and the Mediation Server to the NRS with a unique registration ID and different cost factor. Therefore, if one of the OCS Proxy servers is unavailable, the next one is selected.

High-scale and high availability configuration

The pool of Front End servers processes inbound and outbound traffic. In this example, the Load Balancer routes incoming SIP messages to the less busy server based on a configured algorithm. The Load Balancer VIP

Nortel Communication Server 1000

Nortel Converged Office Fundamentals — Microsoft Office Communications Server 2007

NN43001-121 01.03 Standard

Release 5.0 30 April 2008

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