User manual BARRACUDA NETWORKS TECHNICAL NOTES-CLUSTERING FOR HIGH AVAILABILITY AND CENTRALIZED POLICY MANAGEME

[. . . ] Clustering for High Availability and Centralized Policy Management Barracuda Spam & Virus Firewall High availability and fault tolerance are essential in modern enterprise and service provider networks. Clustering Barracuda Spam & Virus Firewalls enables organizations to meet their high availability and fault tolerance requirements while also providing centralized management of policy, scalability and data redundancy. [. . . ] Barracuda Spam & Virus Firewall clusters are also fault tolerant to temporary network failures or delays because all cluster events and updates are queued on each node. Each individual Barracuda Spam & Copyright 2004-2009, Barracuda Networks Inc. Page 1 of 3 Clustering for High Availability and Centralized Policy Management Barracuda Spam & Virus Firewall Virus Firewalls continues to process email independently and automatically synchronizes quickly as network communications allow. Federated Search Clustering Barracuda Spam & Virus Firewalls provides you with a centralized view of all messages in a cluster through a distributed database architecture. With federated search, you can locate any messages across the cluster by issuing a query from any single Barracuda Spam & Virus Firewall. Unlike centralized database architectures that involve network traffic for all processed messages, this distributed database architecture restricts network traffic to only messages returned with query results. Figure 2 ­ Federated search across the cluster Scalability Because Barracuda Spam & Virus Firewall clustering leverages a distributed database architecture, it is very simple to implement and is easily scalable. As your email traffic volume grows, you can simply add one or more additional Barracuda Spam & Virus Firewalls. Note that clustering is supported on Barracuda Spam & Virus Firewall models 400 and higher, and each Barracuda Spam & Virus Firewall in the cluster must be the same model number. Secure Access and Data Transmission Barracuda Spam & Virus Firewall clustering utilizes encrypted and secure communications for user access, message replication and configuration synchronization across the cluster. Limiting User Access As mentioned above, you can choose to dedicate a single Barracuda Spam & Virus Firewall in the cluster as the Quarantine Host to serve up the end-user interface through which users will access their quarantine inboxes, even though their actual quarantine inbox (primary or secondary) may be hosted by another Barracuda Spam & Virus Firewall in the cluster. Network security is enhanced by limiting enduser access (port 8000 by default) and administration to only one Barracuda Spam & Virus Firewall on the Internet. In this configuration, quarantine notifications from all appliances in the cluster will direct users to that Quarantine Host, and you would direct all email to the other nodes on the cluster. Copyright 2004-2009, Barracuda Networks Inc. Page 2 of 3 Clustering for High Availability and Centralized Policy Management Barracuda Spam & Virus Firewall Secure Message Transmission Data transmission is always encrypted through SSL communication between Barracuda Spam & Virus Firewalls in the cluster. Secure communication is controlled over defined TCP ports. Restricted Access to Configuration Transmission of configuration data between devices on the cluster is secured by a shared password, or "shared secret", which the administrator creates and assigns to every Barracuda Spam & Virus Firewall. This prevents access to configuration parameters from other Barracuda Spam & Virus Firewalls outside the cluster or other network devices. Easy Deployment Deploying clustered Barracuda Spam & Virus Firewalls is easy with the step-by-step instructions documented in the user interface. [. . . ] Generally, MX record load balancing will not distribute the traffic as evenly as a dedicated load balancer. See the Barracuda Networks white paper entitled Load Balancing Using DNS MX Records for more information. Copyright 2004-2009, Barracuda Networks Inc. Page 3 of 3 [. . . ]