Manual Chapter : Configuring SIP Load Balancing

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BIG-IP LTM

  • 15.0.0
Manual Chapter

Configuring SIP Load Balancing

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

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.
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 (default)
An example of SIP session traffic scenario 1
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 for configuring SIP load balancing

Complete these tasks to configure SIP message routing on a system.

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 associate only one protocol profile and one SIP session profile with each transport config.
  6. Click
    Finished
    .

Implementing Low-Latency Electronic Trading with FIX load balancing

Creating a peer

In order to create a peer, you must first ensure that at least one transport configuration and one pool exist in the BIG-IP system configuration.
You 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 messages.
  1. On the Main tab, click
    Local Traffic
    Profiles
    Message Routing
    Diameter
    .
    The Diameter session profiles list screen opens.
  2. On the menu bar, click
    Peers
    .
    The Peers list screen opens.
  3. Click
    Create
    .
    The New Peer 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, select an option to specify how connections are distributed to a remote host.
    Option
    Description
    Per Blade
    The number of connections are distributed and controlled per blade on a VIPRION system.
    Per Peer
    (Default) The number of connections to a remote host is per peer.
    Per TMM
    The number of connections to a remote host is per TMM on the BIG-IP system.
    Per Client
    The number of connections to a remote host is per client connection. Responses are delivered to the connection initiating the request. This option is typically used when implementing a firewall, because of its restrictive functionality.
    The configured
    Connection Mode
    ,
    Number of Connections
    , and
    Ratio
    settings determine how the BIG-IP system uses connections to pool members in delivering messages.
  7. From the
    Pool
    list, select the pool of servers to which the system load balances Diameter 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 configuration that defines the egress message routing peer connection.
  9. In the
    Number of Connections
    field, type the number of allowed connections between the BIG-IP system and the servers in the selected pool.
  10. In the
    Ratio
    field, type the ratio assigned to this peer for use within a static route.
  11. Click
    Finished
    .
A peer determines how the BIG-IP system connects with the servers on your network, and to which servers the system routes and load balances messages.

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.
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.
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. To use 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
      .
    Changing traffic groups, with Connection Mirroring enabled, drops all mirrored connections and loses all persistence data. If you change traffic groups, mirroring must restart.
    The traffic group for the virtual address and mirrored attribute are overwritten by the attached router profile.
  8. Select the
    Connection Mirroring
    check box.
    For connection mirroring to properly function, this device must be a member of a device group.
  9. In the
    Mirrored Message Sweeper Interval
    field, type the 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.

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 Monitors List screen opens.
  2. Click
    Create
    .
    The New Monitor screen opens.
  3. In the
    Name
    field, type a name for the monitor.
  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.
    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.