Diameter Signaling

Diameter signaling traffic is carried on a virtual LAN (VLAN) Signaling A (SIG-A) network, a SIG-B, or SIG-C network. Database replication and high-availability (HA) heartbeat traffic within a site (that is, between the active and standby servers) is sent on an Operation, Administration, and Management (OAM) VLAN network. You can configure the Policy Management topology to send replication and HA heartbeat data between sites (that is, between the active and spare servers) using different VLANs. Replication data can be sent between sites on the OAM (default), SIG-A, SIG-B, SIG-C, or a dedicated replication (REP) network. (Replication traffic between CMP servers always uses the OAM network.) For information on configuring a REP network, see Setting Up a Non-CMP Cluster. In a georedundant topology, servers (with a 1x4 mezzanine card) can communicate with logging and backup servers over a dedicated backup (BKUP) network. However, for Policy Management applications, only backup of CMP systems is typical.

Replication (REP) packets can be marked with a symbolic differentiated services code point (DSCP) value to determine per-hop behavior (PHB). The supported code points are class selector (CS), assured forwarding (AF), and expedited forwarding (EF). The available class selectors are CS1 through CS7. The following AF points are available:

Drop Probability	Class 1	Class 2	Class 3	Class 4
Low	AF11	AF21	AF31	AF41
Medium	AF12	AF22	AF32	AF42
High	AF13	AF23	AF33	AF43

A cluster can be configured to use a secondary HA heartbeat path between georedundant sites in case the primary HA heartbeat network fails. The secondary HA heartbeat path can be configured to use the OAM, SIG-A, SIG-B, SIG-C, or REP network. If the primary HA heartbeat network fails, then the secondary HA heartbeat path continues to send heartbeats between the active and spare servers.

The primary HA heartbeat path is the same as the replication path. The default primary HA heartbeat and replication path is the OAM network. If you configure a different network to carry replication traffic, then that network is also used as the primary HA heartbeat network. In this case, the OAM network could be configured as the secondary HA heartbeat network.

Replication traffic, including a threshold of outstanding updates to a standby or spare server (see Configuring the Upsync Log Alarm Threshold), is displayed in an MPE/MRA Replication Stats report (see Viewing the MPE/MRA Replication Statistics Report).