SIP Configuration

You must ensure there are both sip-interface and sip-config SIP configurations operating on the Oracle Communications Session Border Controller (SBC) for it to participate as a member of an Subscriber-Aware Load Balancer cluster.

With respect to the sip-config, the Subscriber-Aware Load Balancer uses your hostname setting as the identification of the SBC, for example, within its show commands. This allows you to segregate individual SBC behavior on the Subscriber-Aware Load Balancer. In many cases, administrators have already configured an SBC hostname for other purposes. This setting must be unique on each SBC.

westy# configure terminal
westy(configure)# session-router
westy(session-router)# sip-config
westy(sip-interface)# select
westy(sip-interface)# sip-config
westy(sip-interface)# hostname SLB-member1

In a traditional SBC configuration the IP address assigned to a sip-port configuration element is contained within the address space defined by the network interface netmask. This is not be the case for clustered SBCs. Rather, the IP address assigned to the sip-port is identical to the address of an Subscriber-Aware Load Balancer service-port advertised on the access network. The process of encapsulating the packets between the Subscriber-Aware Load Balancer and SBC masks the fact that the IP address the SBC expects to receive IP packets on is different than the Layer 5 address the SBC expects the SIP address on.

Consistency of realm identification is vital to successful and predictable policy-based load balancing. Take particular care to ensure that the realm-id of the sip-interface configuration element mirrors the lb-realm assignments made while configuring distribution rules. See the Distribution Policy Configuration section.

In the following configuration example, the realm-id is LosAngeles. This SBC, when booted, will detect that it is a member of an Subscriber-Aware Load Balancer cluster and register the service port 10.0.0.1:5060/UDP as the realm LosAngeles with the Subscriber-Aware Load Balancer. The Subscriber-Aware Load Balancer will automatically create the SBC group LosAngeles (if it doesn’t exist) or join the SBC to the group LosAngeles (if it is not the first to advertise LosAngeles). Policy statements that direct packets to LosAngeles now consider this SBC as a potential destination, assuming the address:port/protocol also are consistent with the policy’s matching criteria.

This technique allows you to configure the same IP:port/protocol on multiple SBCs, with different realm-id labels, to indicate priority of one SBC or group of SBCs over another. As an example, consider several SBCs geographically situated together with the label LosAngeles, and several other SBCs geographically situated elsewhere with the label NewYork, all with the identical SIP interface and SIP port configuration. A policy can be easily defined to give preference to a source subnet of users in California to the LosAngeles member SBCs, with NewYork as a second priority. This provides flexibility in network design without undue burden in the configuration: SBCs’ tagged with the same realm name are joined in dynamically created SBC groups by the Subscriber-Aware Load Balancer, with no explicit configuration required on the Subscriber-Aware Load Balancer whatsoever.

  1. From superuser mode, use the following ACLI command sequence to access sip-interface configuration mode. While in this mode, you verify the realm-id and assign the newly created IP-in-IP tunnel to a SIP interface.
    westy# configure terminal
    westy(configure)# session-router
    westy(session-router)# sip-interface
    westy(sip-interface)# select
    <realm-id>: LosAngeles
    1: LosAngeles  172.192.1.15:5060
    selection: 1
    westy(sip-interface)# show
    sip-interface
            state                    enabled
            realm-id                 LosAngeles
            ...
            ...
            ...
    westy(sip-interface)#
  2. Use the tunnel-name parameter to assign the IP-in-IP tunnel to the current SIP interface.
    westy(sip-interface)# tunnel-name sipSignaling
    westy(sip-interface)# ?
  3. Use the sip-port command to move to sip-port configuration mode.
    westy(sip-interface)# sip-port
    westy(sip-port)# ?
    address            IP Address
    port               port (default: 5060)
    transport-protocol transport protocol
    tls-profile        the profile name
    allow-anonymous    allowed requests from SIP realm
    ims-aka-profile    ims-aka profile name
    select             select a sip port to edit
    no                 delete a selected sip port
    show               show sip port information
    done               write sip port information
    exit               return to previous menu
    westy(sip-port)#
  4. Use the address, port, and transport-protocol parameters to mirror the address of an existing SLB service port.
    westy(sip-port)# address 10.0.0.1
    westy(sip-port)# port 5060
    westy(sip-port)# transport-protocol udp
    westy(sip-port)#
  5. Use done, exit, and verify-config to complete configuration of this sip-port configuration element.
  6. Repeat Steps 1 through 5 as necessary to verify realm-ids, assign IP-in-IP tunnels, and create mirrored service ports on additional SIP interfaces.