JBoss.orgCommunity Documentation
Mobicents supports the clustering of SIP Servlets-enabled JBoss Application Servers for performance, reliability and failover purposes. Note that only MSS for JBoss Servers can be used as cluster nodes; MSS for Tomcat Containers are not supported.
The SIP Servlets Server uses the JBoss Application Server as its servlet container, and takes advantage of its capabilities, including clustering and failover. For detailed background information about JBoss Application Server clustering refer to the JBoss Application Server Clustering Guide.
Software Prerequisites
Before proceeding, ensure you have correctly configured your JBoss Application Server, according to SIP Servlet Server requirements:
The easiest way to set up a cluster of SIP Servlets-enabled JBoss Application Servers is to install, configure and test the binary distribution on one machine, and then copy the entire installation (directory) to the other machines in the cluster. This is the approach taken in this chapter.
Install a SIP Servlets Server with JBoss by following the instructions detailed in Section 2.1, “SIP Servlet-Enabled JBoss Application Server: Installing, Configuring and Running”.
Afer meeting the requirement you can begin to configure the server Section 5.1.1.2, “Configuring” below.
Once installed, the MSS for JBoss binary distribution requires only minor configuration in order to enable clustering.
SIP, and HTTP session state clustering is pre-configured straight out of the binary distribution. However, to enable session replication in a node, you must tag it as <distributable/>
in the web.xml
descriptor. This can be done either individually per application or globally for all applications.
You will notice that the following instructions modify one or more properties in the configuration files for the "all" Server Configuration Profile. This is evident in the path names given below. When we start each MSS for JBoss node, we will invoke run.sh
(or run.bat
) with the -c all
option, which activates the clustering capabilities for that node. The server will then consult the configuration files under the <topmost_directory>/server/all/
directory, and not in the the <topmost_directory>/server/default/
subdirectories. Therefore, it is important to modify the correct files.
To change the correct profile, open the web.xml
configuration file, which is stored in the <install_directory>/server/all/deploy/jboss-web.deployer/conf/
directory,
Add the empty element <distributable/>
as a child of the root element <web-app>.
This one configuration change is sufficient for enabling clustering capabilities in MSS for JBoss servers for all applications. For further information on session replication and clustering with JBoss, refer to Enabling session replication in your application in the JBoss Application Server Getting Started Guide.
Example 5.1. Enabling Node Session Replication in the Default web.xml Descriptor
<?xml version="1.0" encoding="utf-8"?><?xml version="1.0" encoding="ISO-8859-1"?>
<web-app
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
version="2.4">
<!-- ======================== Introduction ============================== -->
<!-- This document defines default values for *all* web applications -->
<!-- loaded into this instance of Tomcat. As each application is -->
<!-- deployed, this file is processed, followed by the -->
<!-- "/WEB-INF/web.xml" deployment descriptor from your own -->
<!-- applications. -->
<!-- -->
<!-- WARNING: Do not configure application-specific resources here! -->
<!-- They should go in the "/WEB-INF/web.xml" file in your application. -->
<!-- =========== Common Context Params ================================== -->
<!-- JBossInjectionProvider provides resource injection for managed beans. -->
<!-- See JSF 1.2 spec section 5.4 for details. -->
<distributable/>
<context-param>
<param-name>com.sun.faces.injectionProvider</param-name>
<param-value>org.jboss.web.jsf.integration.injection.JBossInjectionProvider</param-value>
</context-param>
Clustering with MSS for JBoss nodes requires running all of the nodes using the "all" Server Configuration Profile, which is specified when you invoke run.sh
or run.bat
.
To run the server on Linux using the "all" Configuration Profile, start the server with the following command:
MSS-jboss-<version>]$ ./bin/run.sh -c all
To run the server on Windows using the "all" Configuration Profile, open the Command Prompt, change your folder to the topmost folder of your MSS for JBoss installation, and issue the following command:
C:Usersuser\<username>My DownloadsMSS-jboss-<version>>binrun.bat -c all
Together with the application server nodes, it is advised to run a SIP load-balancer or an IP load-balancer. The IP load balancer will distribute the traffic evenly between the nodes. A load-balancer is a single entry-point to all nodes. All calls should be made through the load balancer if High Availability is required. For more information about load balancing, refer to Section 5.3.5, “Implementation of the Mobicents Load Balancer”.
By default, the servers are configured with one SIP load-balancer set to the IP address 127.0.0.1
. This is specified in the balancers
attribute in the server.xml
configuration file as follows:
<Service name="jboss.web"
className="org.mobicents.servlet.sip.startup.failover.SipStandardBalancerNodeService"
balancers="127.0.0.1"
sipApplicationDispatcherClassName="org.mobicents.servlet.sip.core.SipApplicationDispatcherImpl"
concurrencyControlMode="None"
darConfigurationFileLocation="conf/dars/mobicents-dar.properties">
Multiple load balancers can be specified and all of them will be updated on the health status of the node. The complete syntax for the balancers string is the following:
<Service name="jboss.web"
...
balancers="ipAddress1:sipPort1:rmiPort1;ipAddress2:sipPort2:rmiPort2;..3...4.."
...>
If the RMI port is omitted port 2000 is assumed, and if the SIP port is omitted 5065 is assumed.
The SIP port specified in the balancers string for each balancer refers to the internal SIP port of the SIP balancer. That is because the internal port faces the cluster nodes directly. Requests coming through the internal port will go to the external port and vice versa. If you put the external port in the balancers
string, then the SIP LB will assume that the requests comes from outside the cluster and it will route it back to some cluster node instead of routing it outside the cluster as expected. Always use the SIP internal port in the balancers
string. Exception to this rule is when a single port is used for internal and external ports in the SIP load balancer. In that case the direction analysis is done based on Via
headers and the requests are routed correctly without extra settings.
When multiple SIP load balancers are specified, the outgoing requests will always go through the first one, or an IP load balancer can be used and the requests will be distributed based on the IP balancer policy. To route the outgoing requests to a particular IP address (the IP load balancer address for example) the outboundProxy
property can be used:
<Service name="jboss.web"
...
balancers="127.0.0.1:5060:2000;127.0.0.1:5160:2100"
outboundProxy="127.0.0.1:5500"
...>
In this example configuration all outbound requests will go through 127.0.0.1:5500, while the node will perform the health checks against two SIP load balancers. If the 127.0.0.1:5500 machine is an IP load balancer it should be configured to spray the SIP load balancers and they will route the requests outside the cluster reliably.
The outboundProxy
attribute overrides the default effect of specifying a SIP port for SIP load balancers in the balancers
string.
Individual nodes in the cluster should be stopped one-by-one, followed by the SIP load balancer. Refer to:
Stopping the SIP load balancer: Section 5.3.7.7, “Stopping”
Stopping MSS for JBoss: Section 2.1.10, “Stopping”
Stopping MSS for Tomcat: Section 2.2.8, “Stopping”
To test your JBoss cluster setup for mid-call failover (Established SIP Dialog), refer to:
A Mobicents SIP Servlets Server for JBoss cluster does not employ any standby nodes. Typically, therefore, proxies and registrars must share the user location table by using a database cluster.
The Mobicents SIP load balancer, which is a SIP Call ID-aware load balancer, is used as the intermediary. The SIP load balancer forwards stateful transaction requests to cluster nodes based on its provisioning algorithm. The SIP load balancer acts as an entry-point to the cluster and distributes the incoming requests between nodes. It is always advised to use a SIP load balancer or an IP load balancer in a cluster configuration.
The SIP Stack used by the Mobicents SIP Servlets for JBoss supports ESTABLISHED SIP DIALOG
failover. This means that failover will occur only on established calls (SIP Dialogs which are in the CONFIRMED state as per RFC 3261) and calls that are in the process of being setup will not be failed over (SIP Dialogs which are in the EARLY state as per RFC 3261).
This choice of implementation has many benefits:
There is no need for standby nodes, because the remaining nodes in a degraded cluster automatically and transparently (to the user) take on the load of the failed node. This can be done because both the SIP load balancer and SIP Servlet-enabled JBoss Application Servers support mid-call failover (Established SIP Dialog).
There is no need to ensure that requests are directed to the correct node, because in a SIP Servlets-enabled JBoss Application Server (or Mobicents JAIN SLEE server) cluster, any node can serve any request to any User Agent (UA).
All hardware is in use, reducing costs.
Maintenance is easier, due to all nodes having nearly-identical configurations.
There are a number of options you can specify for MSS clustering. By default most of them are configured in the "all" server configuration, which is ready to use. In this chapter we will cover the most common configuration options you might need.
The Mobicents SIP load balancer is used to balance the load of SIP service requests and responses between nodes in a SIP Servlets Server cluster. Both MSS for JBoss and MSS for Tomcat servers can be used in conjunction with the SIP load balancer to increase the performance and availability of SIP services and applications.
In terms of functionality, the Mobicents SIP load balancer is a simple stateless proxy server that intelligently forwards SIP session requests and responses between User Agents (UAs) on a Wide Area Network (WAN), and SIP Servlets Server nodes, which are almost always located on a Local Area Network (LAN). All SIP requests and responses pass through the SIP load balancer.
All User Agents send SIP messages, such as INVITE
and MESSAGE
, to the same SIP URI (the IP address and port number of the SIP load balancer on the WAN). The load balancer then parses, alters, and forwards those messages to an available node in the cluster. If the message was sent as a part of an existing SIP session, it will be forwarded to the cluster node which processed that User Agent's original transaction request.
The SIP Servlets Server that receives the message acts upon it and sends a response back to the SIP load balancer. The SIP load balancer reparses, alters and forwards the message back to the original User Agent. This entire proxying and provisioning process is carried out independent of the User Agent, which is only concerned with the SIP service or application it is using.
By using the load balancer, SIP traffic is balanced across a pool of available SIP Servlets Servers, increasing the overall throughput of the SIP service or application running on either individual nodes of the cluster. In the case of MSS for JBoss's </distributed>
capabilities, load balancing advantages are applied across the entire cluster.
The SIP load balancer is also able to fail over requests mid-call from unavailable nodes to available ones, thus increasing the reliability of the SIP service or application. The load balancer increases throughput and reliability by dynamically provisioning SIP service requests and responses across responsive nodes in a cluster. This enables SIP applications to meet the real-time demand for SIP services.
In addition to the SIP load balancing, there are several options for coordinated or cooperative load balancing with other protocols such as HTTP. Typically, a JBoss Application Server will use apache HTTP server with mod_jk, mod_proxy, mod_cluster or similar extension installed as an HTTP load balancer. This apache-based load balancer will parse incoming HTTP requests and it will look for the session ID of those requests in order to ensure all requests from the same session arrive at the same application server. By default, this is done by examining the jsessionid
HTTP cookie or GET parameter and looking for the jvmRoute
assigned to the session. The typical jsessionid
value is of the form <sessionId>.<jvmRoute>
(e.g. mysessionid323424.node1
where node1
is the jvmRoute
component). The very first request for each new HTTP session do not have any session ID assigned, thus apache routes the request to a random application server node. When the node responds it assigns a session ID and jvmRoute
to the response of the request in a HTTP cookie and this response goes back to the client through apache, which keeps track of which node owns which jvmRoute
. Once, the very first request is served this way, the subsequent requests from this session will carry the assigned cookie and the apache load balancer will always route the requests to the node, which advertised itself as the jvmRoute
owner.
Instead of using apache, an integrated HTTP load balancing is also available. The SIP load balancer has an HTTP port where you could direct all incoming HTTP requests. The integrated HTTP load balancer behaves exactly like apache by default, but this behaviour is extensible and can be overridden completely with the pluggable balancer algorithms. The integrated HTTP load balancer is much easier to configure and generally requires no effort, because it reuses most SIP settings ans assumes reasonable default values.
Unlike the native apache, the integrated HTTP load balancer is written completely in Java, thus a performance penalty should be expected when using it. However, the integrated HTTP balancer has an advantage when related SIP and HTTP requests must stick to the same node.
The SIP/HTTP load balancer exposes an interface to allow users to customize the routing decision making for special purposes. By default there are three built-in algorithms. Only one algorithm is active at any time and it is specified with the algorithmClass
property in the configuration file.
It is completely up to the algorithm how and whether to support distributed architecture or how to store the information needed for session affinity. The algorithms will be called for every SIP and HTTP request and other significant events to make more informed decisions.
Users must be aware that, bydefault requests explicitly addressed to a live server node passing through the load balancer will be forwarded directly to the server node. This allows for pre-specified routing use-cases, where the target node is known by the SIP client through other means. If the target node is dead, then the node selection algorithm is used to route the request to an available node.
This algorithm is not distributable. It selects nodes randomly to serve a give Call-ID extracted from the requests and responses. It keeps a map with Call-ID -> nodeId
associations and this map is not shared with other load balancers which will cause them to make different decisions. For HTTP it behaves like apache.
This algorithm is distributable and can be used in distributed load balancer configurations. It extracts the hash value of specific headers from SIP and HTTP messages to decide which application server node will handle the request. Information about the options in this algorithms is available in the balancer configuration file comments.
This algorithm is distributable and is similar to the previous algorithm, but it attempts to keep session affinity even when the cluster nodes are removed or added, which would normally cause hash values to point to different nodes.
When the capacity of a single load balancer is exceeded, multiple load balancers can be used. With the help of an IP load balancer the traffic can be distributed between all SIP/HTTP load balancers based on some IP rules or round-robin. With consistent hash and jvmRoute
-based balancer algorithms it doesn't matter which SIP/HTTP load balancer will process the request, because they would all make the same decisions based on information in the requests (headers, parameters or cookies) and the list of available nodes. With consistent hash algorithms there is no state to be preserved in the SIP/HTTP balancers.
Figure 5.2. Example deployment scenario with IP load balancers serving both directions for incoming and outgoing requests in a cluster
Each individual Mobicents SIP Servlets Server in the cluster is responsible for contacting the SIP load balancer and relaying its health status and regular "heartbeats".
From these health status reports and heartbeats, the SIP load balancer creates and maintains a list of all available and healthy nodes in the cluster. The load balancer forwards SIP requests between these cluster nodes, providing that the provisioning algorithm reports that each node is healthy and is still sending heartbeats.
If an abnormality is detected, the SIP load balancer removes the unhealthy or unresponsive node from the list of available nodes. In addition, mid-session and mid-call messages are failed over to a healthy node.
For more information about this aspect of the load balancer, refer to Section 5.2, “Mobicents SIP Servlets for JBoss: Transparent Failover”.
The SIP load balancer first receives SIP requests from endpoints on a port that is specified in its Configuration Properties configuration file. The SIP load balancer, using a round-robin algorithm, then selects a node to which it forwards the SIP requests. The load balancer forwards all same-session requests to the first node selected to initiate the session, providing that the node is healthy and available.
The Mobicents SIP load balancer appends itself to the Via
header of each request, so that returned responses are sent to the SIP Balancer before they are sent to the originating endpoint.
The load balancer also adds itself to the path of subsequent requests by adding Record-Route headers. It can subsequently handle mid-call failover by forwarding requests to a different node in the cluster if the node that originally handled the request fails or becomes unavailable. The SIP load balancer immediately fails over if it receives and unhealthy status, or irregular heartbeats from a node.
The SIP Servlets Server extends the SipStandardService
class, which extends the Tomcat StandardService
class. The StandardService
class is responsible for implementing the Tomcat Service
interface.
In Tomcat architecture, a service is an intermediate component which resides inside a server, and binds one or more Connectors
to exactly one Engine
. When the service is started, the new SipStandardBalancerNodeService
looks up its configuration information and obtains the SIP load balancer address. The heartbeat and health status is sent to the SIP load balancer address to identify the service as an available node of the cluster.
The node parameters are configurable through their MBean
interfaces; information on their configuration is provided in the following sections.
In advanced configurations, it is possible to run more than one SIP load balancer.
Figure 5.3, “Basic IP and Port Cluster Configuration” describes a basic IP and Port Cluster Configuration. In the diagram, the SIP load balancer is the server with the IP address of 192.168.1.1
.
Software Prerequisites
Running the SIP load balancer requires at least two SIP Servlets Servers as client nodes. Therefore, before configuring the SIP load balancer, we should make sure we've installed a SIP Servlets Server first. The Mobicents SIP load balancer will work with a SIP Servlets-enabled JBoss Application Server or a SIP Servlets-enabled Tomcat Container.
However, if you intend to cluster multiple nodes for performance, reliability and failover purposes, then you will want to install and set up SIP Servlets-enabled JBoss AS nodes, because only they can be clustered, and not SIP-Servlet Tomcat Containers.
To install a SIP Servlet-enabled JBoss Application Server, follow the instructions here: Section 2.1, “SIP Servlet-Enabled JBoss Application Server: Installing, Configuring and Running”.
To install a SIP Servlet-enabled Tomcat Servlet Container, follow these instructions: Section 2.2, “SIP Servlet-Enabled Tomcat Servlet Container: Installing, Configuring and Running”.
The load balancer is located in the sip-balancer
top-level directory of the MSS distribution. You will find the following files in the directory:
The SIP load balancer executable JAR file can be placed anywhere in the file system. It is recommended that the file is placed in the directory containing other JAR executables, so it can be easily located in the future.
Configuring the SIP load balancer and the two SIP Servlets-enabled Server nodes is described in Configuring the Mobicents SIP Load Balancer and Servlet Server Nodes.
Procedure 5.1. Configuring the Mobicents SIP Load Balancer and Servlet Server Nodes
Configure lb.properties Configuration Properties File
Configure the SIP load balancer's Configuration Properties file by substituting valid values for your personal setup. Example 5.2, “Complete Sample lb.properties File” shows a sample lb.properties
file, with key element descriptions provided after the example. The lines beginning with the pound sign are comments.
Example 5.2. Complete Sample lb.properties File
# Mobicents Load Balancer Settings # For an overview of the Mobicents Load Balancer visit http://docs.google.com/present/view?id=dc5jp5vx_89cxdvtxcm # The binding address of the load balancer host=127.0.0.1 # The RMI port used for heartbeat signals rmiRegistryPort=2000 # The SIP port used where client should connect externalPort=5060 # The SIP port from where servers will receive messages # delete if you want to use only one port for both inbound and outbound) # if you like to activate the integrated HTTP load balancer, this is the entry point internalPort=5065 # The HTTP port for HTTP forwarding httpPort=2080 #Specify UDP or TCP (for now both must be the same) internalTransport=UDP externalTransport=UDP # If you are using IP load balancer, put the IP address and port here #externalIpLoadBalancerAddress=127.0.0.1 #externalIpLoadBalancerPort=111 # Requests initited from the App Servers can route to this address (if you are using 2 IP load balancers for bidirectional SIP LB) #internalIpLoadBalancerAddress=127.0.0.1 #internalIpLoadBalancerPort=111 # Designate extra IP addresses as serer nodes #extraServerNodes=222.221.21.12:21,45.6.6.7:9003,33.5.6.7,33.9.9.2 # Call-ID affinity algortihm settings. This algorithm is the default. No need to uncomment it. #algorithmClass=org.mobicents.tools.sip.balancer.CallIDAffinityBalancerAlgorithm # This property specifies how much time to keep an association before being evitcted. # It is needed to avoid memory leaks on dead calls. The time is in seconds. #callIdAffinityMaxTimeInCache=500 # Uncomment to enable the consistent hash based on Call-ID algorithm. #algorithmClass=org.mobicents.tools.sip.balancer.HeaderConsistentHashBalancerAlgorithm # This property is not required, it defaults to Call-ID if not set, cna be "from.user" or "to.user" when you want the SIP URI username #sipHeaderAffinityKey=Call-ID #specify the GET HTTP parameter to be used as hash key #httpAffinityKey=appsession # Uncomment to enable the persistent consistent hash based on Call-ID algorithm. #algorithmClass=org.mobicents.tools.sip.balancer.PersistentConsistentHashBalancerAlgorithm # This property is not required, it defaults to Call-ID if not set #sipHeaderAffinityKey=Call-ID #specify the GET HTTP parameter to be used as hash key #httpAffinityKey=appsession #This is the JBoss Cache 3.1 configuration file (with jgroups), if not specified it will use default #persistentConsistentHashCacheConfiguration=/home/config.xml # Call-ID affinity algortihm settings. This algorithm is the default. No need to uncomment it. #algorithmClass=org.mobicents.tools.sip.balancer.CallIDAffinityBalancerAlgorithm # This property specifies how much time to keep an association before being evitcted. # It is needed to avoid memory leaks on dead calls. The time is in seconds. #callIdAffinityMaxTimeInCache=500 # Uncomment to enable the consistent hash based on Call-ID algorithm. #algorithmClass=org.mobicents.tools.sip.balancer.HeaderConsistentHashBalancerAlgorithm # This property is not required, it defaults to Call-ID if not set, cna be "from.user" or "to.user" when you want the SIP URI username #sipHeaderAffinityKey=Call-ID #specify the GET HTTP parameter to be used as hash key #httpAffinityKey=appsession # Uncomment to enable the persistent consistent hash based on Call-ID algorithm. #algorithmClass=org.mobicents.tools.sip.balancer.PersistentConsistentHashBalancerAlgorithm # This property is not required, it defaults to Call-ID if not set #sipHeaderAffinityKey=Call-ID #specify the GET HTTP parameter to be used as hash key #httpAffinityKey=appsession #This is the JBoss Cache 3.1 configuration file (with jgroups), if not specified it will use default #persistentConsistentHashCacheConfiguration=/home/config.xml #Adjusting the heatbeat. The hearbeat must be specified together with the individual server JAIN SIP property org.mobicents.ha.javax.sip.HEARTBEAT_INTERVAL #If a node doesnt check in within that time (in ms), it is considered dead nodeTimeout=5100 #The consistency of the above condition is checked every heartbeatInterval milliseconds heartbeatInterval=5000 #JSIP stack configuration..... javax.sip.STACK_NAME = SipBalancerForwarder javax.sip.AUTOMATIC_DIALOG_SUPPORT = off // You need 16 for logging traces. 32 for debug + traces. // Your code will limp at 32 but it is best for debugging. gov.nist.javax.sip.TRACE_LEVEL = 32 gov.nist.javax.sip.DEBUG_LOG = logs/sipbalancerforwarderdebug.txt gov.nist.javax.sip.SERVER_LOG = logs/sipbalancerforwarder.xml gov.nist.javax.sip.THREAD_POOL_SIZE = 64 gov.nist.javax.sip.REENTRANT_LISTENER = true
Local IP address, or interface, on which the SIP load balancer will listen for incoming requests.
Port on which the SIP load balancer listens for incoming requests from SIP User Agents.
Port on which the SIP load balancer forwards incoming requests to available, and healthy, SIP Servlets Server cluster nodes.
Port on which the SIP load balancer will establish the RMI heartbeat connection to the application servers. When this connection fails or a disconnection instruction is received, an application server node is removed and handling of requests continues without it by redirecting the load to the lie nodes.
Port on which the SIP load balancer will accept HTTP requests to be distributed across the nodes.
Transport protocol for the internal SIP connections associated with the internal SIP port of the load balancer. Possible choices are UDP
, TCP
and TLS
.
Transport protocol for the external SIP connections associated with the external SIP port of the load balancer. Possible choices are UDP
, TCP
and TLS
. It must match the transport of the internal port.
Address of the IP load balancer (if any) used for incoming requests to be distributed in the direction of the application server nodes. This address may be used by the SIP load balancer to be put in SIP headers where the external address of the SIP load balancer is needed.
The port of the external IP load balancer. Any messages arriving at this port should be distributed across the external SIP ports of a set of SIP load balancers.
Address of the IP load balancer (if any) used for outgoing requests (requests initiated from the servers) to be distributed in the direction of the clients. This address may be used by the SIP load balancer to be put in SIP headers where the internal address of the SIP load balancer is needed.
The port of the internal IP load balancer. Any messages arriving at this port should be distributed across the internal SIP ports of a set of SIP load balancers.
Comma-separated list of hosts that are server nodes. You can put here alternative names of the application servers here and they will be recognized. Names are important, because they might be used for direction-analysis. Requests coming from these server will go in the direction of the clients and will not be routed back to the cluster.
The fully-qualified Java class name of the balancing algorithm to be used. There are three algorithms to choose from and you can write your own to implement more complex routing behaviour. Refer to the sample configuration file for details about the available options for each algorithm. Each algorithm can have algorithm-specific properties for fine-grained configuration.
In milliseonds. Default value is 5100. If a server node doesnt check in within this time (in ms), it is considered dead.
In milliseconds. Default value is 5000 milliseonds. The hearbeat interval must be the same or close to the interval specified in the JAIN SIP property on the server machines - org.mobicents.ha.javax.sip.HEARTBEAT_INTERVAL
The remaining keys and properties in the configuration properties file can be used to tune the JAIN SIP stack, but are not specifically required for load balancing. To assist with tuning, a comprehensive list of implementing classes for the SIP Stack is available from the Interface SIP Stack page on nist.gov. For a comprehensive list of properties associated with the SIP Stack implementation, refer to Class SipStackImpl page on nist.gov.
Configure the server.xml
configuration file
Ensure the following attributes are configured for the <service>
element in server.xml
.
The className
attribute must have the value org.mobicents.servlet.sip.startup.failover.SipStandardBalancerNodeService
instead of org.mobicents.servlet.sip.startup.SipStandardService.
The balancers
attribute must contain a IP address (or list of addresses) of the SIP load balancer(s) to which heartbeat information will be sent.
The sipPathName
attribute must contain the following value org.mobicents.ha
to indicate that the server will be using the Mobicents JAIN SIP HA SIP Stack which is an extension of the JAIN SIP Stack offering transparent replication.
the SIP load balancer uses Java Logging as a logging mechanism. As such you cna configure it through a property file and specify the property file to be used by using the following command -Djava.util.logging.config.file=./lb-logging.properties
. Please refer to JDK logging for more informationon how to configure the Java logging.
On MSS for Tomcat server installations, server.xml
is located in <install_directory>/conf
.
On MSS for JBoss server installations, the default server.xml
configuration file is located in server/default/deploy/jboss-web.deployer
.
On MSS for JBoss installations, with JBoss clustering support enabled, the "all" server.xml
file must be configured. It is located in server/all/deploy/jboss-web.deployer
.
To determine what profile should be altered for each MSS for JBoss installation, refer to Section 5.1, “Mobicents SIP Servlets for JBoss: Clustering Support”.
Both SIP Servlet-enabled JBoss and Tomcat have JMX (Java Management Extensions) interfaces that allow for easy server configuration. The JMX Console is available once the server has been started by navigating to http://localhost:8080/jmx-console/.
Both the balancers
and heartBeatInterval
attribute values are available under serviceName=jboss.web,type=Service
in the JMX Console.
Host names of the SIP load balancer(s) with corresponding addBalancerAddress
and removeBalancerAddress
methods.
Interval at which each heartbeat is sent to the SIP load balancer(s).
The MSS SIP load balancer can work in concert with HTTP load balancers such as mod_jk
. Whenever an HTTP session is bound to a particular node, an instruction is sent to the SIP load balancer to direct the SIP calls from the same application session to the same node.
It is sufficient to configure mod_jk
to work for HTTP in JBoss in order to enable cooperative load balancing. MSS will read the configuration and will use it without any extra configuration. You can read more about configuring mod_jk
with JBoss in your JBoss Application Server documentation.
To use the integrated HTTP load balancer, no extra configuration is needed. If a unique jvmRoute
is specified and enabled in each application server, it will behave exactly as the apache balancer. If jvmRoute
is not present it will use session ID as a hash value and attempt to create sticky session. The integrated balancer can be used together with the apache balancer at the same time.
In addition to the apache behaviour, there is a consistent hash balancer algorithm that can be enabled for both HTTP and SIP messages. For both HTTP and SIP messages, there is a configurable affinity key, which is evaluated and hashed against each unassigned request. All requests with the same hash value will always be routed to the same application server node. For example, the SIP affinity key could be the callee user name and the HTTP affinity key could the “appsession” HTTP GET parameter of the request. If the desired behaviour group these requests, we can just make sure the affinity values (user name and GET parameter) are the same.
Procedure 5.2. Running the SIP Load Balancer and Servlet Server Nodes
Start the SIP Load Balancer
Start the SIP load balancer, ensuring the Configuration Properties file (lb.properties
in this example) is specified. In the Linux terminal, or using the Windows Command Prompt, the SIP Load Balancer is started by issuing a command similar to this one:
java -jar sip-balancer-1.0-20080829.103906-21-jar-with-dependencies.jar lb-configuration.properties
Executing the SIP load balancer produces output similar to the following example:
home]$ java -jar sip-balancer-1.0-20080829.103906-21-jar-with-dependencies.jar lb-configuration.properties Oct 21, 2008 1:10:58 AM org.mobicents.tools.sip.balancer.SIPBalancerForwarder start INFO: Sip Balancer started on address 127.0.0.1, external port : 5060, port : 5065 Oct 21, 2008 1:10:59 AM org.mobicents.tools.sip.balancer.NodeRegisterImpl startServer INFO: Node registry starting... Oct 21, 2008 1:10:59 AM org.mobicents.tools.sip.balancer.NodeRegisterImpl startServer INFO: Node expiration task created Oct 21, 2008 1:10:59 AM org.mobicents.tools.sip.balancer.NodeRegisterImpl startServer INFO: Node registry started
The output shows the IP address on which the SIP load balancer is listening, as well as the external and internal listener ports.
Configure SIP Servlet Server Nodes
SIP Servlets Server nodes can run on the JBoss Application Server, or the Tomcat Servlet Container. The SIP Servlets Server binary distributions define the type of SIP Servlets Server nodes used, and should already be installed from Software Prerequisites.
The server.xml
file specifies the nodes used. Because there is more then one client node specified, unique listener ports must be specified for each node to monitor HTTP and/or SIP connections. Example 5.3, “Changing the SIP Connector Port for Servlet Server Nodes in server.xml” describes the affected element in the server.xml
file.
For the JBoss SIP Servlets Server binary distribution, server.xml
is located in the <install_directory>/server/all/deploy/jboss-web.deployer/
directory. For the Tomcat binary distribution, server.xml
is located in the <install_directory>/conf/
directory.
Example 5.3. Changing the SIP Connector Port for Servlet Server Nodes in server.xml
<!-- Define a SIP Connector -->
<Connector port="5080"
Start Load Balancer Client Nodes
Start all SIP load balancer client nodes.
To test load balancing, the same application must be deployed manually on each node. Two SIP Softphones must be installed.
Procedure 5.3. Testing Load Balancing
Deploy an Application
Ensure that for each node, the DAR file location is specified in the server.xml
file.
Deploy the Location service manually on both nodes.
Start the "Sender" SIP softphone
Start a SIP softphone client with the SIP address of sip:sender@sip-servlets-com
, listening on port 5055. The outbound proxy must be specified as the sip-balancer (http://127.0.0.1:5060)
Start the "Receiver" SIP softphone
Start a SIP softphone client with the SIP address of sip:receiver-failover@sip-servlets-com
, listening on port 5090.
Initiate two calls from "Sender" SIP softphone
Initiate one call from sip:sender@sip-servlets-com
to sip:receiver-failover@sip-servlets-com
. Tear down the call once completed.
Initiate a second call using the same SIP address, and tear down the call once completed. Notice that the call is handled by the second node.
Assuming that you started the JBoss Application Server as a foreground process in the Linux terminal, the easiest way to stop it is by pressing the Ctrl+C key combination in the same terminal in which you started it.
This should produce similar output to the following:
^COct 21, 2008 1:11:57 AM org.mobicents.tools.sip.balancer.SipBalancerShutdownHook run INFO: Stopping the sip forwarder
An IP load-balancer is a network appliance that distributes traffic to an application server (or actual servers) using a load-balancing algorithm. IP load-balancing is often used when the other load-balancers' capacity is exceeded and can not scale further without hardware upgrades.
Routing decisions are made based on OSI Layer 2, 3 or 4 data. This type of load balancer only examines low-level TCP, UDP or ethernet packet structures including MAC addresses, IP addresses, ports, and protocol types (TCP or UDP or other).
An IP load balancer never reads the payload of the TCP/IP packets and therefore never parses SIP or HTTP (or any protocol above OSI Layer 4). Because an IP load balancing device is not SIP or HTTP aware in any way, it is much more performant than mod_jk
or the MSS SIP load-balancer.
In its simplest form, the IP load-balancer usually "owns" the public-facing IP address (known as a VIP). The traffic is routed to actual servers in it's private network similar to NAT. It is also possible to not change the IP address and just work on the MAC address by assuming that all actual servers are configured to accept packets for the VIP address. The features offered by the IP load balancer depend largely on the vendor.
Some examples of Linux-based software load balancers include Red Hat Cluster Suite (RHCS) and Linux Virtual Server (LVS). There are many hardware vendors as well.
One main drawback relating to IP load balancers is that they can not make routing decisions based on SIP messages and (with some exceptions) they can not work cooperatively with HTTP or other load balancers.
Pure IP load balancing is not a recommented option. It is advised to use a distributed load balancer instead. Proper operation with pure IP load balancing depends on the ability of the IP load balancer to establish request affinity based on IP addresses and ports.
First you need to remove the SIP load balancers from any configuration in MSS. In particular the balancers
attribute in server.xml
. and edit the jboss.web engine tag. You should remove the balancers attribute from the Service tag of jboss.web service. This simply removes the default load balancer from the system and the traffic bypasses the SIP load-balancer. Next you must configure MSS to put the IP load balancer IP address in the Via
, Contact
and other system headers where the IP address of the server machine is required. This will ensure that any responses or subsequent SIP requests follow the same path, but always hit the load balancer instead of particular cluster node that may fail. To specify the IP load balancer address in MSS your should edit this file JBOSS_HOME/server/all/deploy/jboss-web.deployer/server.xml
and specify staticServerAddress
such as:
<Connector port="5080" ipAddress = "${jboss.bind.address}" ... staticServerAddress="122.122.122.122" staticServerPort="44" useStaticAddress="true"/>
Depending on your reliability requirements you can omit the configuration described in this section and let the servers use their own IP address in the SIP messages.