Multiple Virtual IP Address

Feature Summary and Revision History

Summary Data

Table 1. Summary Data

Applicable Product(s) or Functional Area

5G-PCF

Applicable Platform(s)

SMI

Feature Default Setting

Disabled – Configuration required

Related Changes in this Release

Not Applicable

Related Documentation

Not Applicable

Revision History

Table 2. Revision History

Revision Details

Release
First Introduced.

2020.01.0

Feature Description

You can now enable the IPv4 communication between PCF and the other network functions such as SMF, NRF, CHF, and UDR through multiple virtual IP addresses (VIP). With a provision to configure discrete VIP addresses or external IP addresses for each rest-ep service and link them to an endpoint, you can prevent sharing of IP addresses between the NFs. Multiple VIPs take the role of a load balancer to offer a high availability environment.

In a scenario where multiple calls are simultaneously made to a distinct network function, the policy service spawns different REST ep services to complete each interaction. PCF spawns a service using the IP address available in the IP pool.

Limitations

In the current release, this feature has the following limitation:

  • PCF supports the configuration of multiple IPs only for IP version 4 (IPv4).

How it Works

After the admin associates an IP address to a network function such as PCF, a new endpoint is linked to the network function through the rest-ep service. This service enables you to connect to the pcf-rest-ep pod.

You can configure multiple IP address for the N7, N36, N28, and Nnrf interfaces. During this process, an individual K8 service resource of type Load Balancer is created for each interface that communicates with the rest-endpoint pod. These IP addresses get listed in the ExternalIP property of the K8 service.

PCF supports multiple IP service communications with one replica of the rest-endpoint pod.

Architecture

This section describes how the network function components interact when the multiple VIP model is implemented.

The multiple VIP architecture focuses on high availability and load-balancing aspect of IP addresses in 5G. With relevance to the multiple VIP graphic, the Policy Engine invokes a new rest-ep service for a NF when you assign an IP address as an external endpoint. All the incoming requests from the network functions, such as NRF and SMF are routed to the rest-ep-service and the traffic is redirected to the pcf-rest-ep pod. The pod has a bilateral communication with the PCF Engine. The rest-ep-service operates as a load balancer.

Figure 1. Multiple VIPs

Configuration Support for Multiple Virtual IP Address

The configuration of the multiple virtual IP address involves the following steps:

Configuring REST Endpoints

This section describes how to configure the IP address, port numbers, and other attributes for a REST endpoint.


Note

Configuration changes to REST EP cause the endpoint to automatically restart. Cisco recommends making such changes only within the maintenance window.

Before configuring the external IP addresses for the PCF REST endpoints, make sure that you configure and deploy the IP addresses using the SMI Deployer.

To configure REST endpoint, use the following configuration in the Policy Ops Center console:

config 
   rest-endpoint 
      interface [ n7 | n15 | n25 | n28 | nnrf ] 
          ip interface_ip_address 
          port interface_port_number 
      ips ip_address 
      port port_number 
      http-connection-limit maximum_inbound_connection_count 
      replicas replica_count 
      inbound-request-timeout-ms inbound_timeout 
      outbound-request-timeout-ms outbound_timeout 
      repository repository_address 
      tracing-service-name tracing_service 
      uri-scheme uri_scheme 
      end

NOTES:

  • For each rest-enpoint, use a separate rest-endpoint ip_address command.

  • interface [ n7 | n15 | n25 | n28 | nnrf ] – Specifies the interface name and IP address that is configured for the external IP. interface_name ip_address must include the interface name such as N7, N36, N28, and NNRF.

    • ip interface_ip_address – Specifies the IP address that is assigned for the interface.

    • port interface_port_number – Specifies the port number for the interface.

      For example, to enable the N15 interface allocate resources such as IP and port number. Once the interface is configured, the PCF-AMF traffic can pass through N15.

  • ips ip_address – Specifies the IP address that is assigned as a REST endpoint external IP address.

  • port port_number – Specifies the port number for the REST endpoint.

  • http-connection-limit maximum_inbound_connection_count – Specifies the maximum number of inbound HTTP connections that the REST endpoint server must accept. Default value is 200.

  • replicas replica_count – Specifies the number of instances of the service-based interface.

  • inbound-request-timeout-ms inbound_timeout – Configures the timeout period after which the inbound request expires. You can configure a single inbound_timeout value for all the configured interfaces or the single interface.

  • outbound-request-timeout-ms outbound_timeout – Configures the timeout period after which the outbound request expires. You can configure a single outbound_timeout value for all the configured interfaces or the single interface.

  • repository repository_address – Configures a repository that the network interface optimizes.

  • tracing-service-name tracing_service – Specifies the service that is used for tracing purpose.

  • uri-scheme uri_scheme – Specifies the URI scheme as HTTP or HTTPs.


Note
If the configured IP address is not accessible, then PCF fails to connect with the other NFs and reports an error message in the service as "Failed to allocate IP for "pcf/udr-rest-ep": no available IPs".

Verifying the REST Endpoints Configuration

This section describes how to verify the REST Endpoints configuration.

After an interface IP address is configured, you can observe a new service with the name as <interface-name>-rest-ep. The service type as ClusterIP gets created within the configured IP address. For example, n36-rest-ep.

If an IP address is not associated to an interface, then PCF considers an external IP address and associates it with the interface.