Site Isolation

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

Enabled - Configuration Required

Related Changes in this Release

Not Applicable

Related Documentation

Not Applicable

Revision History

Table 2. Revision History
Revision Details Release

Introduced instructions to configure the remote system ID in the secondary site while the primary site is undergoing a site isolation procedure.

2021.02.01

First introduced.

2020.02.0

Feature Description

Site isolation is segmenting your PCF environment to create silos of cluster or a standalone CDL instance in a Geographic Redundancy (GR) deployment. Each silo is self-sufficient with access to dedicated resources and network utilities. With this approach, you can upgrade or resolve network issues targeted towards the affected site without impacting any other site.

The site isolation strategy protects against data loss by replicating changes between the original site and the standby site. The secondary site takes over the primary site's traffic workload whenever the primary site is unavailable. After the maintenance activity is completed, you can bring up the primary site and reinstate it to the previous state to process the requests.

How it Works

A site can be unavailable when it is undergoing maintenance level upgrade or experiencing a network issue. During this period, the site cannot manage the traffic that the client directs towards it. In such situations, you can isolate the site so that the traffic workload is switched from a primary site to a secondary site.

Configuring the PCF site isolation feature is a simplified process that involves issuing the commands from the PCF Ops Center console of the primary and secondary sites. The primary-secondary-primary switch includes the following:

  1. From the PCF application dashboard, verify that the primary site has not received any SBA inbound traffic.

  2. In the PCF Ops Center of the primary site, set the PCF registration status to UNDISCOVEREABLE. If the primary site is unavailable, the client automatically contacts the secondary site. Similarly, when the primary site comes online, the client attempts to connect to the primary site. No manual intervention is required to bring up the secondary site.

    The primary and secondary sites are always synchronized, so the data integrity is maintained.

    To determine whether all the traffic requests are switched successfully to the secondary site, review the traffic status on the Grafana dashboard.

  3. After the traffic is switched to a secondary site, you can bring down the primary site and take the required actions to upgrade or resolve the accessibility issues.


    Note

    If you intend to isolate the site without disrupting the GR replication system, do not shut down the primary site.

  4. In the primary site, ensure that only the Ops Center-specific pods are running in the PCF product namespace. The rest of the pods must be terminated.

  5. After the planned activities are completed on the primary site, and it is ready to be brought back to a consistent state, bring up the primary site.

  6. Ensure that the sessions on the primary site are synchronized with the recent updates on the secondary site. You can verify the CDL changes and compare the CLD local session count on both the sites

Prerequisites

This section describes the prerequisites that must be met to configure the site isolation feature.

Before bringing down a site, ensure that all the in-progress traffic requests are completed.

Configuring the Site Isolation Feature

You can configure the site isolation feature from the PCF Ops Center.

Configuring the site isolation feature involves the following steps:

  1. Configuring the PCF Registration Status

  2. Bringing Down the Primary Site

  3. Determining the Pod Status

  4. Bringing Up the Primary Site

  5. Verifying if the Sessions are Synchronized

  6. Verifying if the Primary Site is Up

Configuring the PCF Registration Status

This section describes how to configure PCF as undiscoverable.

To configure the PCF registration status to undiscoverable, use the following configuration from the primary site's PCF Ops Center: 

config 
  service-registration 
   profile 
    nf-status { REGISTERED | UNDISCOVERABLE } 
    commit 
    exit

NOTES:

  • config – Enters the configuration mode.

  • service-registration – Enters the service registration configuration mode.

  • profile – Enters the profile configuration mode.

  • nf-status { REGISTERED | UNDISCOVERABLE } – Enters the profile configuration mode.

Bringing Down the Primary Site

This section describes how to bring the primary site down.


Note

If you want to isolate the site without disrupting the GR replication system, do not bring down the primary site.

The secondary site takes over the primary site’s traffic when the primary site is down or in the UNDISCOVERABLE state. To bring the primary site down, use the following configuration on the PCF Ops Center: 

config 
  system mode shutdown 
  commit 
  exit

NOTES:

  • config – Enters the configuration mode.

  • system mode shutdown – Shuts down the site.

Configuring the Remote System ID

This section describes how to configure the remote system ID in the secondary site using the siteID of the primary site or the opposite way.

To configure the remote system ID, use the following configuration:

  1. After primary site is unavailable, configure the “remote-system-id” in the secondary site using the siteID of the primary site. Use this configuration in the PCF Ops Center: 

    config 
  cdl 
    datastore session 
      slot notification remote-system-id [ siteID ] 
      site1 
    exit 
     exit

    NOTES:

    • config – Enters the configuration mode.

    • cdl – Enters the CDL configuration mode.

    • datastore session – Enters the datastore session configuration.

    • slot notification remote-system-id [ siteID ] – Specifies the siteID for the primary site.

    Sample Configuration

    The following is a sample configuration for specifying the siteID.

    cdl datastore session
slot notification remote-system-id [ 1 ]. <- 1 is the siteID of
site1
exit

  2. Continue upgrading the primary site. Notifications for primary site record timerExpiry are sent to the secondary site.

For more information on CDL components, refer to the Cisco Common Data Layer documentation.

Determining the Pod Status

This section describes how to verify that only the PCF Ops Center-specific pod is running on the secondary site.

To verify if the Ops Center-specific pod is running in the PCF product namespace, use the following:

Use the following command in the CEE Ops Center of the secondary site: 

show cluster pods

Alternatively, on the master node, use the following command to display the pod status associated with a specific namespace.

kubectl get pods -n pcf_namespace

Bringing Up the Primary Site

This section describes how to bring up the primary site.

To bring up the primary site, use the following configuration on the PCF Ops Center:

config 
  system mode running 
  commit 
  exit

NOTES:

  • config – Enters the configuration mode.

  • system mode running – Configures the system mode as “running”.

After bringing up the primary site, remove the primary site's siteID from the secondary site's “remote-system-id” list.

To remove siteID, use the following configuration:

no cdl datastore session slot notification remote-system-id site_id
Sample Configuration
no cdl datastore session slot notification remote-system-id [1]

When the primary site is available, ensure to change the nf-status from UNDISCOVERABLE to REGISTERED to enable PCF to serve the SMF traffic. For information on how to change the nf-status, see Configuring the PCF Registration Status.

Verifying if the Sessions are Synchronized

This section describes how to verify if the sessions are synchronized between the sites.

The site isolation implementation requires that sessions are synchronized between the primary-secondary-primary sites. After the sites are switched, you can validate that synchronization is successful by reviewing the slots' state and indexes in both the sites. If the state of the slots and indexes is STARTED or ONLINE, the synchronization status is a success. Another approach is to ensure that the local session count on both the sites match. The local session counts are synchronized between the primary and secondary site when the sessions are replicated.

To display the CDL status in the secondary site, use the following commands on the PCF Ops Center:

  • To display the state of slots and indexes, run the following:

    cdl show status

  • To display the local session count details, run the following:

    cdl show status

Verifying if the Primary Site is Up

This section describes how to confirm if the primary site is brought up successfully.

To verify whether the primary site is up, review the deployment status and percentage usage using the following commands on the PCF Ops Center: 

show system status deployed 
show system status percent-ready

Example:

The following example displays the output of the show system status deployed and show system status percent-ready commands: 

system status deployed true
system status percent-ready 100.0

NOTES:

  • The deployment status of the system must be true.

  • The percentage of the system must be 100. When the system is 100 percent ready, ensure that the nf-status is changed from UNDISCOVERABLE to REGISTERED. This procedure enables PCF to operate and handle the service traffic from SMF.