SIP cluster routing
Cluster routing rules is the method used to define how the SIP proxy routes messages to specific clusters in the cell.
A single SIP proxy can front multiple SIP clusters. If we are running more than one cluster of applications on the backend and want to use a single set of proxy servers, the proxy tier will need certain information in order to distinguish which cluster an initial request (one not in a pre-existing dialog with no affinity or route built-in) should be routed to.
In order to do this, SIP uses a set of cluster routing rules which allows the proxy to properly distinguish each request. Unlike HTTP, which can usually do this using the URI, there may be numerous other factors applicable in SIP.
Each SIP proxy is configured with a default cluster which is used to route all messages that do not have an associated cluster routing rule. Cluster routing rules, which dictate how messages get routed to the various backend clusters being fronted, can be defined at each proxy.
Cluster routing rules
Routing rules can be based on:
- Message type
- To: field
- From: field
- Destination address
- Source address
- Arbitrary header name with a unique value to distinguish the cluster
Cluster routing rules are used to route only messages associated with new dialogs. Once a dialog is established, a method to route to the specific cluster is embedded in SIP messages.
Related:
SIP high availability Browse all SIP topics