Manual Chapter : Configuring SIP Load Balancing

Applies To:

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BIG-IP LTM

  • 13.0.1, 13.0.0
Manual Chapter

Overview: Configuring a SIP proxy

You can use the BIG-IP® system as a Session Initiation Protocol (SIP) proxy. When the BIG-IP system is placed between your SIP routers, session border controllers, and soft switches, you can configure the system to route and load balance SIP messages across the servers on your SIP network.

This graphic illustrates the relationships of the configuration objects that you must configure on the BIG-IP system.

SIP proxy configuration objects

SIP proxy configuration objects

Task summary

About managing MRF SIP session traffic

Through the SIP Session Profile, you can use Message Routing Framework (MRF) to manage SIP traffic across pool members by means of configuring and using Via headers. When you configure Via headers to manage SIP traffic, dependencies between settings apply, enabling you to steer traffic and control requests and responses, as necessary.

Note: When a client Via header only specifies an address, without specifying a port, the BIG-IP® system uses default port 5060. For example, if a client sends a request with Via header SIP/2.0/TCP 192.168.20.1, in SIP session traffic scenario 1 (default), the BIG-IP system sends a response to the client with Via header SIP/2.0/TCP 192.168.20.1/5060.

Example: SIP session traffic scenario 1 (default)

In SIP session traffic scenario 1 (default), the BIG-IP system receives a request with a Via1 header from a client, and inserts a Via2 header into the request before forwarding the request to the server. When the server provides a response, the BIG-IP system removes the Via2 header from the response, before forwarding the response to the client. If the originating connection no longer exists, the Via2 header that BIG-IP system inserted is no longer available; consequently, the BIG-IP system uses the Via1 header, forwarding the message to the client IP address and port specified by that Via header.

An example of SIP session traffic scenario 1

An example of SIP session traffic scenario 1 (default)

When configuring this scenario, the following SIP Session Profile settings apply.

SIP Session Profile control Setting or value
Honor Via Enabled
Do Not Connect Back Disabled
Insert Via Header Enabled
Custom Via Not applicable

Example: SIP session traffic scenario 2

In SIP session traffic scenario 2, the BIG-IP system receives a request with a Via1 header from a client, and inserts a Via2 header into the request before forwarding the request to the server. When the server provides a response, the BIG-IP system removes the Via2 header from the response, before forwarding the response to the client. When the originating connection no longer exists, then the BIG-IP system drops the response message and increments the statistic for Messages failed due to connection dropped.

An example of SIP session traffic scenario 2

An example of SIP session traffic scenario 2

When configuring this scenario, the following SIP Session Profile settings apply.

SIP Session Profile control Setting or value
Honor Via Enabled
Do Not Connect Back Enabled
Insert Via Header Enabled
Custom Via Not applicable

Example: SIP session traffic scenario 3

In SIP session traffic scenario 3, the BIG-IP system receives a request with a Via1 header from a client, and inserts a Via2 header into the request before forwarding the request to the server. When the server provides a response, the BIG-IP system removes the Via2 header from the response, before forwarding the response to the client. If the originating connection no longer exists, then the Via header that BIG-IP system inserted is no longer available; consequently, the BIG-IP system uses the next available Via header, but, because the Honor Via setting is Disabled, the BIG-IP system does not forward the message to the client IP address and port specified by that Via header.

An example of SIP session traffic scenario 3

An example of SIP session traffic scenario 3

When configuring this scenario, the following SIP Session Profile settings apply.

SIP Session Profile control Setting or value
Honor Via Disabled
Do Not Connect Back Disabled
Insert Via Header Enabled
Custom Via Not applicable

Example: SIP session traffic scenario 4

In SIP session traffic scenario 4, the BIG-IP system receives a request with a Via1 header from a client, and inserts a Via2 header into the request before forwarding the request to the server. When the server provides a response, the response from the BIG-IP to the client must be managed by means of an iRule, for example, MR::message nexthop TMM:flow_id or MR::message route virtual vs_name host ip:port.

An example of SIP session traffic scenario 4

An example of SIP session traffic scenario 4

When configuring this scenario, the following SIP Session Profile settings apply.

SIP Session Profile control Setting or value
Honor Via Not applicable
Do Not Connect Back Not applicable
Insert Via Header Enabled
Custom Via Custom Via header value, for example: SIP/2.0/TCP www.siterequest.com:4343 or SIP/2.0/SCTP 10.10.4.32

Example: SIP session traffic scenario 5

In SIP session traffic scenario 5, the BIG-IP system receives a request with a Via1 header from a client, but does not insert a Via header into the request before forwarding the request to the server. When the server provides a response, the BIG-IP system uses the client Via1 header in the response to forward the message to the client IP address and port specified by that Via header.

An example of SIP session traffic scenario 5

An example of SIP session traffic scenario 5

When configuring this scenario, the following SIP Session Profile settings apply.

SIP Session Profile control Setting or value
Honor Via Enabled
Do Not Connect Back Not applicable
Insert Via Header Disabled
Custom Via Not applicable

Example: SIP session traffic scenario 6

In SIP session traffic scenario 6, the BIG-IP system receives a request with a Via1 header from a client, but does not insert a Via header into the request before forwarding the request to the server. Instead, the BIG-IP system uses the Via1 header specified in the request. When the server provides a response, the BIG-IP system uses the Via1 header in the response, but does not forward the message to the client IP address and port specified by that Via header.

An example of SIP session traffic scenario 6

An example of SIP session traffic scenario 6

When configuring this scenario, the following SIP Session Profile settings apply.

SIP Session Profile control Setting or value
Honor Via Disabled
Do Not Connect Back Not applicable
Insert Via Header Disabled
Custom Via Not applicable

Configuration objects required for a SIP proxy

This table names and describes the objects necessary to configure the BIG-IP system as a SIP proxy.

Configuration Objects Description
Session Profile Defines how BIG-IP processes SIP messages, including the data used to persist SIP connections.
Transport config Defines how BIG-IP connects with the servers on your SIP network.
Pool Defines how BIG-IP load balances connections across a group of servers.
Peer Defines how BIG-IP connects with the servers on your network and to which servers the system routes and load balances SIP messages.
Static route Defines how BIG-IP routes SIP messages.
Router profile Defines an instance of a SIP router.
Virtual Server Defines the destinations in your network, including the servers that process incoming SIP requests and the pool members that process connections between BIG-IP and your SIP network.

Task summary

Complete these tasks to configure SIP message routing on a BIG-IP® system.

Task list

Creating a SIP session profile

Create a SIP session profile to define how the BIG-IP® system processes SIP messages, including the data the system uses to persist SIP connections.
  1. On the Main tab, click Local Traffic > Profiles > Message Routing > SIP .
    The SIP transport config list screen opens.
  2. On the menu bar, click Session Profiles.
    The Session Profiles list screen opens.
  3. Click Create.
    The New SIP Session Profile screen opens.
  4. In the Name field, type a unique name for the SIP session profile.
  5. From the Persist Key list, select the value the system uses for persistence of a SIP session. The options are:
    Option Description
    Call-ID The system uses the value in the Call-ID header field in the SIP message.
    Custom The system uses the value of a custom key specified in an iRule.
    Src-Addr The system uses the originating IP address in the SIP message.
  6. From the Persist Type list, select one of these options:
    Option Description
    Session Persistence is enabled.
    None Persistence is disabled.
  7. In the Persist Timeout (seconds) field, type the number of seconds before a SIP session persistence record expires.
  8. Click Finished.

Creating a transport config

Ensure that at least one SIP session profile exists in the BIG-IP® system configuration.
Create a transport config to define how the BIG-IP system connects with the servers on your network when routing and load balancing SIP messages.
  1. On the Main tab, click Local Traffic > Profiles > Message Routing > SIP .
    The SIP session profiles list screen opens.
  2. On the menu bar, click Transport Config.
    The New Transport Config screen opens.
  3. Click Create.
  4. In the Name field, type a unique name for the transport config.
  5. For the Profiles setting, move both a transport protocol profile (TCP, UDP, or SCTP) and a SIP session profile from the Available list to the Selected list.
    You can only associate one protocol profile and one SIP session profile with each transport config.
  6. Click Finished.

Creating a pool

You can create a pool of servers that you can group together to receive and process traffic.
  1. On the Main tab, click Local Traffic > Pools .
    The Pool List screen opens.
  2. Click Create.
    The New Pool screen opens.
  3. In the Name field, type a unique name for the pool.
  4. Using the New Members setting, add each resource that you want to include in the pool:
    1. (Optional) In the Node Name field, type a name for the node portion of the pool member.
    2. In the Address field, type an IP address.
    3. In the Service Port field, type a port number, or select a service name from the list.
    4. (Optional) In the Priority field, type a priority number.
    5. Click Add.
  5. Click Finished.
  6. Repeat these steps for each pool you want to create.
The new pool appears in the Pools list.

Creating a peer

Ensure that at least one transport config and one pool exist in the BIG-IP® system configuration.
Create a peer to define how the BIG-IP system connects with the servers on your network and to which servers the system routes and load balances SIP messages.
  1. On the Main tab, click Local Traffic > Profiles > Message Routing > SIP .
    The SIP session profiles list screen opens.
  2. On the menu bar, click Peers.
    The Peers list screen opens.
  3. Click Create.
    The New Peers screen opens.
  4. In the Name field, type a unique name for the peer.
  5. In the Description field, type a description of the peer.
  6. From the Connection Mode list, specify how connections are limited for this peer. The options are:
    Option Description
    Per Blade The number of connections to this peer is per blade on a VIPRION system.
    Per Peer The number of connections to this peer is per peer.
    Per TMM The number of connections to this peer is per TMM on the BIG-IP system.
    Per Client The number of connections to a remote host is per client connection.
  7. From the Pool list, select the pool of servers to which the system load balances SIP messages.
    In the case where the calls should be always sent to a single SIP Server, you will still need to create a pool with a single member (the SIP Server), and add the same to the peer.
  8. From the Transport Config list, select the transport config that defines how the BIG-IP system communicates with the servers on your network.
  9. Click Finished.

Creating a static route

Ensure that at least one peer and one virtual server exist in the BIG-IP® system configuration.
Create a static route when you want to route SIP messages from specific clients to specific domains, and load balance those SIP messages across a group of peers. If the configured attributes of a static route match the attributes in a SIP message, the system forwards the message to a member of the pool associated with one of the peers.
Note: The BIG-IP system can use multiple SIP session profiles in a single routing instance, because a different profile can be associated with each member of a pool.
  1. On the Main tab, click Local Traffic > Profiles > Message Routing > SIP .
    The SIP session profiles list screen opens.
  2. On the menu bar, click Static Routes.
    The Static Routes list screen opens.
  3. Click Create.
    The New Route screen opens.
  4. In the Name field, type a unique name for the static route.
  5. In the Request URI field, type the value found in the request-uri of a SIP message that the system matches when routing a message.
  6. In the From URI field, type the value found in the From field of a SIP message that the system matches when routing a message.
  7. In the To URI field, type the value found in the To field of a SIP message that the system matches when routing a message.
  8. From the Virtual Server list, select the virtual server from which the system receives client requests for this static route.
    If you do not select a virtual server, the system uses this static route to route SIP messages originating from any client.
  9. From the Peer Selection Mode field, select how the system selects the Peer to route a SIP message to:
    Option Description
    Ratio Peer selection is based on the ratio that is set for each peer in the Selected list.
    Sequential Peer selection is based on the order of the peers in the Selected list.
  10. For the Peers setting, move the peers that define the servers to which the system load balances SIP messages from the Available list to the Selected list.
  11. Click Finished.

Creating a SIP router profile

Before you start this task, ensure that at least one static route exists on the BIG-IP® system.
Create a SIP router profile to define how a router handles SIP traffic.
Note: A SIP routing profiles binds the virtual server that processes SIP requests from clients with the peers that connect with the servers on your SIP network.
  1. On the Main tab, click Local Traffic > Profiles > Message Routing > SIP .
    The SIP transport config list screen opens.
  2. On the menu bar, click Router Profiles.
    The Router Profiles list screen opens.
  3. Click Create.
    The New SIP Router Profile screen opens.
  4. In the Name field, type a unique name for the SIP router profile.
  5. In the Settings area, select the Custom check box.
  6. From the Operation Mode list, select Load Balancing.
  7. Optional: For use with connection mirroring, configure the Traffic Group setting.
    1. Clear the Inherit traffic group from current partition / path check box.
    2. From the list, select a traffic group, such as, traffic-group-1.
    Important: Changing traffic groups, with Connection Mirroring enabled, drops all mirrored connections and loses all persistence data. If you change traffic groups, mirroring must restart.
    Note: The traffic group for the virtual address and mirrored attribute are overwritten by the attached router profile.
  8. Optional: Select the Connection Mirroring check box.
    Note: For connection mirroring to properly function, this device must be a member of a device group.
  9. In the HA Message Sweeper Interval field, type a value (in milliseconds) for the frequency of the mirrored message sweeper.
  10. For the Static Routes setting, move routes that define how the BIG-IP system load balances SIP traffic from the Available list to the Selected list.
  11. Click Finished.

Creating a virtual server to handle SIP client requests

Ensure that both a SIP session profile and a SIP router profile exist in the BIG-IP® system configuration.
Create a virtual server to handle SIP client requests.
  1. On the Main tab, click Local Traffic > Virtual Servers .
    The Virtual Server List screen opens.
  2. In the Name field, type a unique name for the virtual server.
  3. From the Type list, select Message Routing.
  4. In the Destination Address/Mask field, type an address, as appropriate for your network.
    The supported format is address/prefix, where the prefix length is in bits. For example, an IPv4 address/prefix is 10.0.0.1 or 10.0.0.0/24, and an IPv6 address/prefix is ffe1::0020/64 or 2001:ed8:77b5:2:10:10:100:42/64. When you use an IPv4 address without specifying a prefix, the BIG-IP® system automatically uses a /32 prefix.
  5. In the Service Port field, type 5060 to route SIP traffic or 5061 to route TLS traffic.
  6. From the Configuration list, select Advanced.
  7. From the Application Protocol list, select SIP.
  8. From the Session Profile list, select a SIP session profile.
  9. From the Router Profile list, select a SIP router profile.
  10. Click Update.

Configuration objects required for a SIP proxy

This table names and describes the objects necessary to configure the BIG-IP system as a SIP proxy.

Configuration Objects Description
Session Profile Defines how BIG-IP processes SIP messages, including the data used to persist SIP connections.
Transport config Defines how BIG-IP connects with the servers on your SIP network.
Pool Defines how BIG-IP load balances connections across a group of servers.
Peer Defines how BIG-IP connects with the servers on your network and to which servers the system routes and load balances SIP messages.
Static route Defines how BIG-IP routes SIP messages.
Router profile Defines an instance of a SIP router.
Virtual Server Defines the destinations in your network, including the servers that process incoming SIP requests and the pool members that process connections between BIG-IP and your SIP network.

About checking pool member health

You can configure the BIG-IP® system to monitor pool member health using a SIP monitor. Use a SIP monitor to check the health of a host with an active SIP session. The SIP monitor also monitors a SIP connection independent of a specific SIP session and marks a host that had been marked down, but is online again, as available.

Task summary

Perform these tasks to configure health monitors and apply the monitors to a pool:

Creating a SIP monitor

Create a SIP monitor to mark a pool member as down when that server stops responding and then to mark the pool member as available when service is restored.
  1. On the Main tab, click Local Traffic > Monitors .
    The Monitor List screen opens.
  2. Click Create.
    The New Monitor screen opens.
  3. Type a name for the monitor in the Name field.
  4. From the Type list, select SIP.
    The screen refreshes, and displays the configuration options for the SIP monitor type.
  5. Configure additional settings based on your network requirements.
  6. Click Finished.

Adding a health monitor to a pool

Add health monitors to a pool when you want the BIG-IP system to monitor the health of the pool members. Repeat this procedure for each desired pool.
  1. On the Main tab, click Local Traffic > Pools .
    The Pool List screen opens.
  2. Click the name of the pool you want to modify.
  3. For the Health Monitors setting, in the Available list, select a monitor type, and click << to move the monitor to the Active list.
    Tip: Hold the Shift or Ctrl key to select more than one monitor at a time.
  4. Click Finished.
The new pool appears in the Pools list.

About viewing SIP session and router statistics

You can view statistics for SIP sessions and routes.

Task summary

Viewing SIP session statistics

Ensure that at SIP session router profile are assigned to at least one virtual server.
When you want to see how the BIG-IP® system is handling SIP communications, you can view statistics per SIP session profile.
  1. On the Main tab, click Statistics > Module Statistics > Local Traffic .
    The Local Traffic statistics screen opens.
  2. From the Statistics Type list, select Profiles Summary.
  3. In the Details column for the SIP Session profile, click View to display detailed statistics about SIP sessions.

Viewing SIP router statistics

Ensure that at SIP session and SIP router profile are assigned to at least one virtual server.
When you want to see how the BIG-IP® system is handling SIP message routing, you can view statistics per SIP router profile.
  1. On the Main tab, click Statistics > Module Statistics > Local Traffic .
    The Local Traffic statistics screen opens.
  2. From the Statistics Type list, select Profiles Summary.
  3. In the Details column for the SIP Router profile, click View to display detailed statistics about the routing of SIP messages.