This section provides information for network engineering teams responsible for the deployment of Solace appliances in the DMZ to provide high-availability connectivity into the underlying Layer 2 switch infrastructure.
If there is no requirement for physical separation between internally-facing subnets and externally-facing subnets within the DMZ, then the typical Solace network connectivity options can be used, that is, a Link Aggregation Group (LAG) for 1GE connectivity or port bonding for 10GE connectivity.
In cases where physical separation between subnets within the DMZ is required, more care must be taken. This figure shows a typical deployment using an 8x1GE NAB to provide redundancy on both the intranet-facing (that is, internal) and internet-facing (that is, external) sides. In this case, a LAG is used to provide port and link redundancy facing the intranet, while individual IP interfaces (one per port) are used facing the internet. Typically, the external firewall (for example, BigIP appliance from F5) monitors the availability of each internet-facing IP interface on the Solace appliance, and then load balances incoming HTTP requests to available IP interfaces based on URLs (as discussed in Session Load Balancing to DMZ Appliances).
In deployments using a 2x10GE NAB, one port is connected to the subnet facing the intranet, while the other port is connected to the subnet facing the internet. Thus, there is no port or link redundancy.
Solace appliance active/active redundancy is typically not used with appliances in the DMZ since the URL routing rules of the external firewall, combined with the ability of the firewall to monitor the status of Solace interfaces, allows for an N:1 resiliency model, whereby the load from one failed appliance can either be switched to another spare or standby appliance, or spread among existing appliances, thereby providing more cost-effectiveness with high availability.