Operating Systems: i5/OS
             Personalize the table of contents and search results
SIP high availability
SIP uses the high availability features in WebSphere Application
Server to offer a comprehensive high availability (HA) solution.
The SIP in WebSphere HA solution is described in the following topics:
SIP HA architectural considerations
- Each container is handling state replication and SIP traffic.
- UDP/TCP/Multicast is used for state replication and SIP protocol.
- Complete session state is replicated between all servers in the replication
domain.
- Each replication domain is optimal at two servers. Three servers per replication
domain does not perform as well because each server must maintain a copy of
all session data in the replication domain, but on a failure only half the
servers replicated data is activated on any of the remaining servers.
- The number of SIP proxy servers per blade is dependent on the number of
cluster addresses configured at the IP Sprayer.
SIP proxy configuration considerations
- No call state information is stored at the SIP proxy.
- If the IP sprayer is configured for MAC forwarding:
- The SIP proxy must listen on the loopback address that corresponds to
a cluster address configured at the IP sprayer.
- The IP sprayer configuration dictates the number of SIP proxies per node
(or blade).
- Each configured cluster address can have at most one corresponding SIP
proxy instance per node.
Core groups and Distribution and Consistency Services (DCS)
A
core group is a set of processes which establish a high-availability domain
to monitor and replicate state to one another. Each core group member communicates
with one another through DCS. DCS handles elections, quorums, and heartbeats
(virtual or TCP keepalive). DCS communicates with its peers via either Multicast/TCP
or Reliable Multicast/UDP.
The core group coordinator is elected by
quorum. The default order can be changed. The core group coordinator:
For more information on core groups, see Core groups (high availability domains)
DCS failure detection
DCS failure detection includes:
- Active failure detection – a tunable heartbeat mechanism monitoring:
- Time between heartbeats
- Heartbeats lost before declaring failure
- TCP KEEP_ALIVE / Sockets closing
- Looking at hardware assist features
Sub-topics
Replicating SIP sessions
SIP session affinity and failover
Upgrading SIP applications
SIP cluster routing
SIP IP sprayer
SIP load balancer
Related tasks
Browse all SIP topics
  Â