IP Address Management

Feature Summary and Revision History

Summary Data

Table 1. Summary Data

Applicable Product(s) or Functional Area

SMF

Applicable Platform(s)

SMI

Feature Default Setting

IPAM: Enabled – Always-on

Unique IP Pools for UPF: Disabled – Configuration required to enable

Related Changes in this Release

Not Applicable

Related Documentation

Not Applicable

Revision History

Table 2. Revision History

Revision Details

Release

Added support for the following features:

  • New calls with static IP address.

  • Quarantine queue size.

  • IP address validation with CDL Configuration and statistics.

2021.02.0

IP Address Validation with CDL Configuration introduced.

2021.02.0

Updated quarantine time range to 3600 seconds.

2021.02.0

VRF Support introduced.

2020.02.5

First introduced.

Pre-2020.02.0

Feature Description

IP Address Management (IPAM) is a method of tracking and managing IP addresses of a network. IPAM is one of the core components of the subscriber management system. Traditional IPAM functionalities are insufficient in Cloud-Native network deployments. Hence, IPAM requires additional functionalities to work with the Cloud-Native subscriber management system. The Cloud-Native IPAM system is used in various network functions, such as SMF and PCF.

The IPAM system includes the following functionalities to serve the Cloud Native and Control and User Plane Separation (CUPS) architecture:

  • Centralized IP Resource Management—Based on the needs of the Internet Service Provider (ISP), the Control Plane (CP) is deployed either on a single (centralized) cluster or multiple (distributed) clusters. For multiple cluster deployments, the IPAM automatically manages the single IP address space across the multiple CPs that are deployed in the distributed environment.

  • IP Address Range Reservation per User Plane—For subscribers connecting to the Internet core, the User Plane (UP) provides the physical connectivity. The UP uses the summary routes to advertise subscriber routes to the Internet core. For CPs that are managing multiple UPs, the CP reserves a converged IP subnet to the UPs. In such a scenario, the IPAM splits the available address space into smaller address ranges and assigns it to different UPs.

  • IP Address Assignment from Pre-Reserved Address Ranges—When subscribers request for an IP address, the IPAM assigns addresses from the pre-reserved address range of their respective UP.

How it Works

IPAM uses the following sub-modules for the Cloud-Native subscriber management system:

  • IPAM Server—This module manages the complete list of pools and address space configurations. The IPAM server splits the configured address ranges into smaller address ranges statically or dynamically to distribute them to IPAM cache modules. The IPAM server is deployed as a centralized entity to serve group of Cloud-Native clusters or can be an integrated entity within a single cluster.

  • IPAM Cache—This module receives the free address ranges from the IPAM server and allocates the individual IP addresses to the IPAM clients. Usually, the IPAM cache is deployed in a distributed mode running within each cluster to communicate with the co-located or remotely-located IPAM server. The IPAM cache also handles address range reservation per UP and pool threshold monitoring. The IPAM server and cache modules can run as an integrated mode.

  • IPAM Client—This module handles the request and release of an individual IP address from the IPAM cache for each IP managed end-device. The IPAM client is tightly coupled with a respective network function.

IPAM Integration in SMF

Feature Description

The IP Address Management (IPAM) is a technique for tracking and managing the IP address space of a network. A core component of the subscriber management system, the IPAM, provides all the functionalities necessary for working with the Cloud-Native subscriber management system. Also, the IPAM acts as a generic IP address management system for the different network functions, such as the SMF and Policy Control Function (PCF).

Architecture

This section describes the IPAM integration in the SMF architecture.

IPAM Integration

The IPAM and SMF reside in the Application Services layer.

  • SMF Node Manager Application—The SMF Node Manager application handles the UPF, ID resource, and IP address management. Hence, the SMF Node Manager application integrates IPAM cache and IPAM client modules. The UPF manager uses the IPAM client module for address range reservation per UPF.

  • SMF Service Application— The SMF Service application provides PDU session services. During session establishment and termination, the IP addresses are requested and released back. The SMF Service application invokes the IPC to Resource Manager (RMGR) in Node Manager, which receives (free) the IP from the IPAM module.

  • IPAM Server Application—Based on the deployment model, the IPAM Server application can run as an independent microservice, as a part of the same cluster, or in a remote cluster. For standalone deployments, the IPAM Servers are an integral part of the IPAM cache.

Components

This section describes the different components of the IPAM system.

IPAM Sub-Modules

The IPAM system includes the following sub-modules:

  • IPAM Server – The IPAM server module manages the complete list of pools and address space configuration. It splits the configured address ranges into smaller address ranges (statically and dynamically) and distributes it to the IPAM cache modules. You can deploy the IPAM server either as a centralized entity to serve a group of cloud native clusters or as an integrated entity within a single cluster.

  • IPAM Cache – The IPAM cache acquires free address ranges from the IPAM server and allocates individual IP addresses to the IPAM clients. Deployed in a distributed mode running within each cluster, the IPAM cache communicates with co-located and remotely located IPAM servers. Additionally, the IPAM cache takes care of the address range reservation per data plane and pool threshold monitoring.

  • IPAM Client – The IPAM client module handles the request and release of the individual IP addresses from the IPAM cache for each IP managed end-device. Based on the use cases, the IPAM client module caters the needs of specific network functions (such as SMF, PCF, and so on).

How it Works

This section describes the call flows pertaining to the integration of the IPAM in the SMF.

Call Flows

The following call flow depicts the integration of the IPAM in the SMF.

Figure 1. IPAM Integration Call Flow
Table 3. IPAM Integration Call Flow Description
Step Description
1 IPAM populates the local cache and cache pod with the data configured under IPAM pool configuration. Split the address ranges according to the split size configured under address range.
2 The Node Manager (NM) receives UPF discovery or registration request.
3 The NM forwards the UPF registration request to IPAM for a given DNN or address type.
4 IPAM finds the pool for the given tag and address type and allocates a free address range against the given UPF key.
5 Register the UPF response, status, and route information.
6 The SMF service performs bring up of PDU session. The NM forwards the request to IPAM for the address allocation request.
7 IPAM receives the request for address allocation for tag, UPF key, Authority and Format Identifier (AFI), and Group Identifier (GrID).
8 IPAM allocates free address from the previously allocated address range and responds with the status and allocated address, and route information.
9 The SMF service performs bring down of PDU session. The NM forwards the request to IPAM for address release request.
10 IPAM receives the request for address release for pool name, UPF key, AFI, and GrID.

11

IPAM adds the address to free list of the reserved address range and responds with the status and route information.

12

IPAM receives UPF deregistration request with tag, UPF key, and AFI.

13

Release all the address ranges from the pool associated to the tag, UPF key, and AFI. Then, move the address range to the free list.

14

IPAM sends the UPF deregistration response along with the status and route information.

Configuring IPAM

This section describes how to configure the IPAM in the SMF.

Configuring the IPAM in the SMF involves the following steps:

  1. Configuring IPv4 Address Ranges

  2. Configuring IPv6 Address Ranges

  3. Configuring IPv6 Prefix Ranges

  4. Configuring SMF Tags

  5. Configuring IPv4 Address Range Threshold

  6. Configuring IPv6 Address Range Threshold

  7. Configuring IPv6 Prefix Range Threshold

  8. Configuring IPv4 Address Range Split

  9. Configuring IPv6 Address and Prefix Address Range Split

  10. Configuring Global Threshold

  11. Configuring IPAM Source


Note

In release 2021.02 and later, IPAM pools must be associated to a Geographic Redundancy (GR) instance. That is, you must configure GR instance ID in the IPAM Configuration mode. This configuration is not backward compatible. If you are upgrading SMF to 2021.02 or a later release from a release prior to 2021.02, make sure you first remove the old IPAM configuration and apply the new configuration after the Ops center is accessible.

Configuring IPv4 Address Ranges

To configure the IPv4 address ranges, use the following sample configuration:

config 
   ipam  
      instance gr_instance_id 
         address-pool pool_name 
            vrf-name vrf_name 
            ipv4 
               address-range start_ipv4_address end_ipv4_address 
               commit

NOTES:

  • ipam : Enter the IPAM configuration mode.

  • address-pool pool_name : Specify the name of the address pool. pool_name must be a string.

  • vrf-name vrf_name : Specify the virtual routing and forwarding (VRF) name of the pool.

  • ipv4 : Enter the IPv4 mode of the pool.

  • address-range start_ipv4_address end_ipv4_address : Specify the start address and end address of IPv4 address range in dotted-decimal notation.

The following is an example configuration.

config 
   ipam  
      instance 1 
         address-pool p1
                  vrf-name one
                  ipv4
                     address-range 209.165.200.225 209.165.200.253
                     address-range 209.165.201.1 209.165.201.30
                     end
Verifying the IPv4 Address Range of a Pool

Use the show ipam pool_name ipv4-addr command to view the IPv4 address ranges for the given pool name. Based on the configuration, the address ranges are dynamically split. You can also view whether the address range is free or allocated to a data plane (user plane) using this command.

The following is an example output of the show ipam pool_name ipv4-addr command. 

show ipam pool p1 ipv4-addr 
===================================================================
Flag Indication: S(Static) O(Offline)
===================================================================
StartAddress          EndAddress    AllocContext     Flag
=================================================================== 
209.165.200.225    209.165.200.253  Upf-100                   
209.165.201.1      209.165.201.30   Upf-200                   
209.165.202.129    209.165.202.158  Free:NM1                   






===================================================================

Configuring IPv6 Address Ranges

To configure the IPv6 address ranges, use the following sample configuration:

config 
   ipam  
      instance gr_instance_id 
         address-pool pool_name 
            vrf-name vrf_name 
            ipv6 
               address-range start_ipv6_address end_ipv6_address 
               commit

NOTES:

  • address-pool pool_name : Specify the name of the address pool. pool_name must be a string.

  • vrf-name vrf_name : Specify the VRF name of the pool.

  • ipv6 : Enter the IPv6 mode of the pool.

  • address-range start_ipv6_address end_ipv6_address : Specify the start address and end address of IPv6 address range in colon-separated hexadecimal notation.

The following is an example configuration.

config 
   ipam  
      instance 1 
         address-pool p1
                  vrf-name one
                  ipv6
                     address-range 1::1 1::1000
                     address-range 2::1 2::1000
                     end

Configuring IPv6 Prefix Ranges

To configure the IPv6 prefix ranges, use the following sample configuration:

config 
   ipam 
      instance instance_id 
         address-pool pool_name 
            vrf-name vrf_name 
            ipv6 
               prefix-ranges 
                  prefix-range prefix_value prefix-length length 
                  commit

NOTES:

  • address-pool pool_name : Specify the name of address pool. pool_name must be a string.

  • vrf-name vrf_name : Specify the VRF name of the pool. vrf_name must be a string.

  • ipv6 : Enter the IPv6 mode of the pool.

  • prefix-ranges : Enter the prefix ranges mode.

  • prefix-range prefix_value prefix-length length : Specify the IPv6 prefix range and the IPv6 prefix length.

The following is an example configuration.

config
   ipam  
      instance 1 
         address-pool p3
                  vrf-name three
                  ipv6
                     prefix-ranges
                        prefix-range 1:1:: prefix-length 48
                        prefix-range 2:1:: prefix-length 48
                        end
Verifying the IPv6 Address Prefix Range of a Pool

Use the show ipam pool pool_name ipv6-prefix command to view the prefix ranges for the given pool name. Based on the configuration, the address ranges are dynamically split. You can also view whether the address range is free or allocated to a data plane (user plane) using this command.

The following is an example output of the show ipam pool pool_name ipv6-prefix command. 

show ipam pool p1 ipv6-prefix 
======================================================================================
Flag Indication: S(Static) O(Offline)
======================================================================================
StartAddress                 EndAddress                   AllocContext         Flag
====================================================================================== 
aaaa:bbbb:ccc0::/64    aaaa:bbbb:ccc4::/64          Upf-100                     
aaaa:bbbb:dd00::/64    aaaa:bbbb:dd12::/64          Upf-200                     
bbbb:cccc:ee00::/64    bbbb:cccc:ee12::/64          Free:NM1                    
bbbb:cccc:ff00::/64    bbbb:cccc:ff12::/64          Free:NM0                    
xxxx:yyyy:zz00::/64    xxxx:yyyy:zz12::/64          Free:CP

Configuring SMF Tags

To configure the SMF tags, use the following sample configuration:

config 
   ipam 
      instance gr_instance_id 
         address-pool pool_name 
            tags 
               nssai nssai_value 
               dnn dnn_name 
               serving-area serving_area_value 
               commit

NOTES:

  • address-pool pool_name : Specify the name of the address pool. pool_name must be a string.

  • tags : Specify the pool tags to set additional properties for a pool in generic manner.

    • nssai nssai_value : Specify the NSSAI tag for the pool. nssai_value must be a string.

    • dnn dnn_value : Specify the DNN tag for the pool. dnn_value must be a string.

    • serving-area serving_area_value : Specify the serving area tag for the pool. serving_area_value must be a string.

The following is an example configuration.

config
   ipam  
      instance 1 
         address-pool
                  tags
                     nssai one
                     dnn two
                     serving-area three
                     end

Configuring IPv4 Address Range Threshold

IPAM keeps monitoring the pool usage threshold. Based on the configured threshold value, IPAM requests for next free address range or releases the address range.

To configure the IPv4 threshold, use the following sample configuration:

config 
   ipam 
      instance gr_instance_id 
         address-pool pool_name 
            ipv4 
               threshold 
                  upper-threshold percentage 
                  commit

NOTES:

  • address-pool pool_name : Specify the name of the address pool. pool_name must be a string.

  • ipv4 : Enter the IPv4 mode of the pool.

  • threshold : Enter the threshold sub-mode.

  • upper-threshold percentage : Specify the IPv4 upper threshold value in percentage.

The following is a sample configuration.

config
   ipam  
      instance 1 
         address-pool p1
                  ipv4
                     threshold
                        upper-threshold 80
                        end
Verifying the Threshold of a Pool

Use the show ipam pool command to view the summary of current threshold of each pool.

The following is an example output of the show ipam pool command. 

show ipam pool 
================================================================ 
PoolName   Ipv4Utilization  Ipv6AddrUtilization  Ipv6PrefixUtilization 
================================================================ 
  p1               80%            80%              0% 
  p2               75%            0%               70% 
================================================================

Configuring IPv6 Address Range Threshold

To configure the IPv6 address range threshold, use the following sample configuration:

config 
   ipam 
      instance gr_instance_id 
         address-pool pool_name 
            ipv6 
               address-ranges 
                  threshold 
                     upper-threshold percentage 
                     commit

NOTES:

  • address-pool pool_name : Specify the name of the address pool. pool_name must be a string.

  • ipv6 : Enter the IPv6 mode of the pool.

  • address-ranges : Enter the IPv6 address ranges sub-mode.

  • threshold : Enter the threshold sub-mode.

  • upper-threshold percentage : Specify the IPv6 upper threshold value in percentage.

The following is an example configuration.

config
   ipam  
      instance 1 
         address-pool p2
                  ipv6
                     address-ranges
                        threshold
                           upper-threshold 75
                           end

Configuring IPv6 Prefix Range Threshold

To configure the IPv6 prefix range threshold, use the following sample configuration:

config 
   ipam 
      instance gr_instance_id 
         address-pool pool_name 
            ipv6 
               prefix-ranges 
                  threshold 
                     upper-threshold percentage 
                     commit

NOTES:

  • address-pool pool_name : Specify the name of the address pool. pool_name must be a string.

  • ipv6 : Enter the IPv6 mode of the pool.

  • prefix-ranges : Enter the IPv6 prefix ranges sub-mode.

  • threshold : Enter the threshold sub-mode.

  • upper-threshold percentage : Specify the IPv6 upper threshold value in percentage.

The following is an example configuration.

config
   ipam  
      instance 1 
         address-pool p3
                  ipv6
                     prefix-ranges
                        threshold
                           upper-threshold 78
                           end

Configuring IPv4 Address Range Split

To configure the IPv4 address range split, use the following sample configuration:

config 
   ipam
      instance gr_instance_id 
         address-pool pool_name 
            ipv4 
               split-size per-cache number_of_addresses 
               split-size per-dp number_of_addresses 
               commit

NOTES:

  • address-pool pool_name : Specify the name of the address pool. pool_name must be a string.

  • ipv4 : Enter the IPv4 mode of the pool.

  • split-size per-cache number_of_addresses : Specify the number of IPv4 addresses per chunk for IPAM cache allocation. Specify in the power of 2. The IPAM server consumes this configuration.

    number_of_addresses must be an integer in the range of 2-262144.

  • split-size-per-dp number_of_addresses : Specify the number of IPv4 addresses per chunk for data plane allocation. Specify in the power of 2. The IPAM cache consumes this configuration.

    number_of_addresses must be an integer in the range of 2-262144.

The following is an example configuration.

config
   ipam  
      instance 1 
         address-pool p1
                  ipv4
                     split-size per-cache 1024
                     split-size per-dp 256
                     end

Configuring IPv6 Address and Prefix Address Range Split

To configure the IPv6 address and prefix address range split, use the following sample configuration:

config 
   ipam
      instance gr_instance_id 
         address-pool pool_name 
            ipv6 
               address-ranges 
                  split-size per-cache number_of_addresses 
                  split-size per-dp number_of_addresses 
                  exit 
               prefix-ranges 
                  split-size per-cache number_of_addresses 
                  split-size per-dp number_of_addresses 
                  commit

NOTES:

  • address-pool pool_name : Specify the name of the address pool. pool_name must be a string.

  • ipv6 : Enter the IPv6 mode of the pool.

  • address-ranges : Enter the IPv6 address-ranges sub-mode.

  • split-size per-cache number_of_addresses : Specify the number of IPv4 addresses per chunk for IPAM cache allocation. Specify in the power of 2. The IPAM server consumes this configuration.

    number_of_addresses must be an integer in the range of 2-262144.

  • split-size-per-dp number_of_addresses : Specify the number of IPv4 addresses per chunk for data plane allocation. Specify in the power of 2. The IPAM cache consumes this configuration.

    number_of_addresses must be an integer in the range of 2-262144.

  • prefix-ranges : Enter the IPv6 prefix ranges sub-mode.

The following is an example configuration.

config
   ipam  
      instance 1 
         address-pool p1
                  ipv6
                     address-ranges
                        split-size per-cache 4096
                        split-size per-dp 1024
                        exit
                     prefix-ranges
                        split-size per-cache 8192
                        split-size per-dp 2048
                        end

Configuring Global Threshold

To configure the global threshold, use the following sample configuration:

config 
   ipam
      instance gr_instance_id 
         threshold 
            ipv4-addr percentage 
            ipv6-addr percentage 
            ipv6-prefix percentage 
            commit

NOTES:

  • threshold : Enter the threshold sub-mode.

  • ipv4-addr percentage : Specify the IPv4 threshold value in percentage.

  • ipv6-addr percentage : Specify the IPv6 threshold value in percentage.

  • ipv6-prefix percentage : Specify the IPv6 prefix threshold value in percentage.

The following is an example configuration.

config
   ipam  
      instance 1 
         threshold
                  ipv4-addr 80
                  ipv6-addr 75
                  ipv6-prefix 70
                  end
Verifying the Details of a Pool

This section describes how to verify the integration of IPAM in the SMF.

Use the show ipam pool pool_name command to view more details of a specific pool name.

The following is an example output of the show ipam pool pool_name command. 

show ipam pool p1 
-------------------------------------------------------- 
Ipv4Addr   [Total/Used/Threshold] = 7680 / 7680 / 80% 
Ipv6Addr   [Total/Used/Threshold] = 0 / 0 / 0.00% 
Ipv6Prefix [Total/Used/Threshold] = 512 / 512 / 80% 
Instance ID = 1 
--------------------------------------------------------

Configuring IPAM Source

To configure the IPAM source, use the following sample configuration:

config 
   ipam
      instance gr_instance_id 
         source local 
            source external ipam 
               host ip_address 
               port port_number 
               vendor type 
               commit

NOTES:

  • source local : Enter the local data store as the pool source.

  • source external ipam : Enter the external IPAM server as the pool source.

  • host ip_address : Specify the host name of the external IPAM server.

  • port port_number : Specify the port of the external IPAM server.

  • vendor type : Specify the vendor type of the external IPAM server.

The following is an example configuration.

config
   ipam 
      instance 1 
         source external ipam
            host 209.165.200.225
            port 10000
            vendor cisco
            end

Verifying the IPAM Integration Configuration

This section describes how to verify the integration of IPAM in the SMF.

Verifying the Details of a Data Plane

Use the show ipam dp data_plane_name command to view details of a specific data plane (user plane).

The following is an example output of the show ipam dp data_plane_name command. 

show ipam dp UPF-100 
-------------------------------------------------------- 
Ipv4Addr   [Total/Used/Threshold] = 512 / 100 / 20% 
Ipv6Addr   [Total/Used/Threshold] = 0 / 0 / 0.00% 
Ipv6Prefix [Total/Used/Threshold] = 512 / 300 / 70% 
Instance ID = 1 
--------------------------------------------------------

Verifying the Threshold for Data Plane

Use the show ipam dp command to view the summary of the current threshold for each data plane (User Plane).

The following is an example output of the show ipam dp command. 

show ipam dp 
================================================================ 
DpName     Ipv4Utilization  Ipv6AddrUtilization  Ipv6PrefixUtilization 
================================================================ 
UPF-100           20%             40%               70% 
UPF-200           40%             20%               20% 
================================================================

Verifying the IPv4 Address Range Assigned to a Data Plane

Use the show ipam dp data_plane_name ipv4-addr command to view the IPv4 address ranges assigned to a data plane.

The following is an example output of the show ipam dp data_plane_name ipv4-addr command. 

show ipam dp UPF-100 ipv4-addr 
==============================================================================================
Flag  Indication: S(Static) O(Offline) R(For Remote Instance)
G:N/P Indication: G(Cluster InstId) N(Native NM InstId) P(Peer NM InstId)
====================================================================================================
StartAddress          EndAddress       AllocContext   Route              G:N/P   Utilization   Flag
====================================================================================================
209.165.200.225  209.165.200.253  Pool-1        209.165.200.224/27 1:1/0     99.60%           
209.165.201.1    209.165.201.30   Pool-2        209.165.201.0/27   1:1/0     99.60%        R  
==============================================================================================

Verifying the IPv6 Address Range Assigned to a Data Plane

Use the show ipam dp data_plane_name ipv6-prefix command to view the IPv6 address ranges assigned to a data plane.

The following is an example output of the show ipam dp data_plane_name ipv6-prefix command. 

show ipam dp UPF-100 ipv6-prefix 
==============================================================================================================================
Flag  Indication: S(Static) O(Offline) R(For Remote Instance)
G:N/P Indication: G(Cluster InstId) N(Native NM InstId) P(Peer NM InstId)
==============================================================================================================================
StartAddress                  EndAddress                AllocContext       Route                   G:N/P    Utilization   Flag
==============================================================================================================================
2001:DB80:8f20::              2001:fc20:8f20:ffff::     ims-ipv6-pool1(n6) 2001:fc20:8f20::/48      1:1/0    99.60%
2001:fc20:8f21::              2001:fc20:8f21:ffff::     ims-ipv6-pool1(n6) 2001:fc20:8f21::/48      1:0/1    99.80%
2001:fc20:8f22::              2001:fc20:8f22:ffff::     ims-ipv6-pool1(n6) 2001:fc20:8f22::/48      1:0/1    0.00%         R
2001:fc20:8f23::              2001:fc20:8f23:ffff::     ims-ipv6-pool1(n6) 2001:fc20:8f23::/48      1:1/0    0.00%         R
2001:fc20:8f49::              2001:fc20:8f49:ffff::     ims-ipv6-pool1(n6) 2001:fc20:8f49::/48      1:1/0    34.42%
2001:fc20:8f4f::              2001:fc20:8f4f:ffff::     ims-ipv6-pool1(n6) 2001:fc20:8f4f::/48      1:0/1    33.58%
==============================================================================================================================

Static IP Support

Feature Description

IPAM is the core component of the subscriber management system. Traditional IPAM functionalities prove insufficient in the Cloud Native network deployments. Hence, IPAM requires more functionalities to work with the Cloud Native subscriber management system.

The Static IP Support feature enables the support of static IP on the SMF using IPAM. This feature supports the following functionalities:

  • Static pool configuration—dynamic addition and deletion of static IP pool or static IP address range when the system is running.

  • Splits static address ranges into smaller chunks and associates them with the configured UPFs

  • Enables program routes according to static address range reservation during UPF association

  • Enables secondary authentication under the DNN profile

  • Selects UPF based on reserved address range and Framed-IP received from the Authentication response

  • Handle UPF addition, deletion, and Sx path failure

  • Add a DNN to an existing UPF

Calls with Static IP Address

The SMF supports calls with static IP address and validates if the IP address belongs to the static pool.

The SMF supports Create Session Request with static IP address and also handles Create Session Request received with PAA. The SMF validates if the requested IP address is configured under static pool and assigns the same IP address for the session. If the IP address is not configured under static pool, then SMF rejects the session.


Important

In Release 2021.02, the SMF does not support fallback to dynamic IP allocation.

The following behavior is applicable only to sessions with static IP address.

  • If the SMF receives static IP in Subscription Response from UDM during the 5G Session Create procedure, it assigns the same IP address to the UE session if the IP is configured under static pool. If the IP address is not configured under static pool, then SMF rejects the session.

  • If the RADIUS interface is enabled and if the RADIUS server returns the static IP address, then SMF ignores the IP address received in Create Session Request or Subscription Response.

How it Works

This section provides a brief of how the Static IP Support feature works.

The SMF receives a framed IP address of the subscriber from external AAA servers, such as RADIUS. While IPAM is not involved in individual IP address management in this scenario, it still handles the route management and UPF management for static address ranges.

IPAM splits the ‘static’ address ranges equally according to number of UPFs present in the SMF configuration. Unlike dynamic IP, IPAM splits all static IP address ranges and assigns them for all configured UPFs. IPAM involves and selects an UPF when the external AAA server returns the framed IP of the subscriber. IPAM looks for the route which includes this static IP and then selects the UPF where the route is already configured.

The following figure shows how the static IP address is assigned to the configured UPFs.

Figure 2. Static IP Address Management Procedure


  1. IPAM splits the static ranges into equal number of address ranges based on the number of configured UPFs.

  2. The UPMGR programs the corresponding static routes on the associated UPFs.

  3. Subscribers get static IP from RADIUS server authorization response.

  4. SMF service selects the right UPF based on address ranges and UPF map allocation from the Node Manager.

Address Range Split

Splitting a given address range into smaller address ranges is a key functionality of the IPAM server and IPAM cache. The following guidelines determine address range split:

  • Size of a split address range depends on the configured value or the default value as per the Authority and Format Identifier (AFI) type.

  • Size of a split address range must be a power of 2 or at least to the closest of it. That is, it should be able to represent the split range in subnet/mask notation such that a route can be added in the data plane (user plane) if required.

  • Configured or default address range size must be at the power of 2.

The address range must be split into smaller ranges immediately on configuration or initial start-up. This helps in better sorting of address ranges based on size and faster allocation during actual address range allocation requests. The address range exchange between modules is always in the mentioned size.

Table 4. Examples of IPv4 Address Range Split

Address Range

Split Size (number of addresses per range)

Split Ranges

(* Odd sized ranges)

Route Notation

209.165.200.225 - 209.165.200.254

128

[1] 209.165.200.225 – 209.165.200.254

[2] 209.165.202.129 – 209.165.202.158

[1] 209.165.200.224/27

[2] 209.165.202.128/27

209.165.201.1 – 209.165.201.30

256

[1] 209.165.200.224 – 209.165.200.254

[2] 209.165.201.0 – 209.165.201.30

[3] 209.165.202.128 – 209.165.202.158

...

[n] 209.165.200.225 – 209.165.200.253

[1] 209.165.201.1/27

[2] 209.165.200.224/27

[3] 209.165.202.128/27

...

[n] 209.165.201.0/27

209.165.200.229 – 209.165.200.253

256

[1] 209.165.201.1 – 209.165.201.30 *

[2] 209.165.202.129 – 209.165.202.158

[3] 209.165.200.225 – 209.165.200.253 *

[1] 209.165.201.0/27

[2] 209.165.200.224/27

[3] 209.165.202.128/27
Table 5. Examples of IPv6 Address Range Split

Address Range

Split Size (number of addresses per range)

Split Ranges

(* Odd sized ranges)

Route Notation

1:: - 1::1000

1024

[1] 1:: – 1::3FF

[2] 1::400 – 1::7FF

[3] 1::800 – 1::BFF

[4] 1::C00 – 1::FFF

[1] 1::/118

[2] 1::400/118

[3] 1::800/118

[4] 1::C00/118

1::3 - 1::1DEF

1024

[1] 1::3 – 1::3FF *

[2] 1::400 – 1::7FF

[3] 1::800 – 1::BFF

…

[n] 1::1C00 – 1::1DEF *

[1] 1::/118

[2] 1::400/118

[3] 1::800/118

…

[n] 1::1C00/118

Examples of IPv6 Address Range Split

Prefix split needs two length fields for performing the split.

  • Network length

  • Host length

Prefixes are split between these two length fields and a new route is calculated.

Example 1: network-length = 48, prefix-length = 64

Total (64-48) = 16 bits (that is, 65536 prefixes are available for the split)

Example 2: network-length = 32, prefix-length = 56

Total (56-32) = 24 bits (that is, 16 million prefixes available for the split)


Note
For SMF, the host-length is hard-coded as ‘64’. Only network-length can be configured using the CLI.
Table 6. Examples of IPv6 Address Range Split

Prefix Range

Split Size (number of addresses per range)

Split Ranges

(* Odd sized ranges)

Route Notation

1:2:3::

Nw-len = 48

Host-len = 64

8192

[1]1:2:3:: ... 1:2:3:1fff

[2]1:2:3:2000:: ... 1:2:3:2fff::

[3]1:2:3:3000:: ... 1:2:3:3fff::

...

[1]1:2:3::/51

[2]1:2:3:2000/51

[3]1:2:3:3000/51

...

Call Flows

This section describes the static IP call flow.

The following figure shows the static IP address allocation call flow.

Figure 3. Static IP Call Flow


Table 7. Static IP Call Flow Description
Step Description
1

Configure the static address ranges and UPF list.

2

Split the static address ranges into equal number of ranges for UPFs.
3

Enable program routes for the assigned static address range.
4 Bring up the session.
5

Enable secondary authentication under the DNN profile.
6

The SMF sends the Authentication Request to the RADIUS server.

The RADIUS server sends an Authentication Response with the static IP of the subscriber. The SMF selects the UPF based on the static IP and continues with the programming.

7 Complete the subscriber programming.

Adding a DNN

This section describes the sequence of operations for adding a DNN.

  1. Create a static IP pool in IPAM with the corresponding DNN.

  2. Add a DNN Profile.

  3. If applicable, add the UPFs.

  4. Associate the IP address ranges of the DNN to the available UPFs.


Note

The route is added as part of RegisterUpf requests during explicit Sx association.

Adding a Static IP Address Range

This section describes the sequence of operations for adding a static IP address range in SMF.

  • If new static IP address range is added to a single stack IP pool, the IP address ranges are split according to the configuration and associated with available UPFs in load sharing manner.

    1. Similar to initial association, intermediate association is also done based on the number of IP addresses against the number of configured UPFs.

    2. If UPF is already registered with IPAM:

      • Route addition is triggered, or else

      • No immediate action is taken

  • If a dual stack pool is configured, all IP address ranges, both IPv4 and IPv6 are associated with the UPF, which is the least loaded.

    • If UPF is already registered with IPAM:

      • Route addition is triggered, or else

      • No immediate action is taken

Adding a Static IP Pool

This section describes the sequence of operations for adding a static IP pool in SMF.

  • If a single stack IP pool is configured, the IP address ranges are split according to the configuration and associated with available UPFs in load-sharing manner.

    1. Similar to initial association, intermediate association is also done based on the number of IP addresses against the number of configured UPFs.

    2. If UPF is already registered with IPAM:

      • Route addition is triggered, or else

      • No immediate action is taken

  • If a dual stack pool is configured, all IP address ranges, both IPv4 and IPv6 are associated with the UPF, which is the least loaded.

    • If UPF is already registered with IPAM:

      • Route addition is triggered, or else

      • No immediate action is taken

Adding the UPF

This section describes the sequence of operations for adding the UPF.

  1. When a UPF is added, NodeMgr sends the list of IPs to IPAM.

  2. When new static IP pool or static IP address range is configured, this feature enables route association for UPFs based on load balancing model.


    Note

    The same procedure is applicable when a new or existing DNN is added to a new or existing UPF respectively.

  3. To redistribute existing static IP pools or ranges to the new UPF, use the following procedure:

    • Mark a pool/range offline

    • Clear the subscribers

    • Delete IP pool or range

    • Add the IP pool or range again.

      This step allocates the chunks to the new UPF.

Deleting the UPF

This section describes the sequence of operations for deleting an existing UPF.

  1. To delete an existing UPF, it is first marked "offline".

    Run the appropriate CLI commands to manually clear the sessions.

  2. The NodeMgr notifies IPAM about the UPF removal.

  3. IPAM moves the static address ranges from all DNNs of the removed UPF to other available UPFs.

  4. The Nodemgr initiates ReleaseUpf to IPAM. IPAM releases dynamic address ranges to the free list.

  5. The Nodemgr sends an N4 Association Release message to UPF and to clean up UPF from the cache.


Note

If the UPF is not marked offline and a manual clean-up is not performed before its removal, the system behavior might be erratic.

Deleting a Static IP Address Range

This section describes the sequence of operations for deleting a static IP address range in SMF.

  1. To delete an IP address range from a static IP pool, it is first marked "offline".

  2. Reject new calls, which have the IP address assigned from the offline IP address range.

  3. Remove the existing subscribers. To remove the existing subscribers, run the following CLI commands:

    clear subscriber ipv4-range { pool_name  | start_of_range } 
clear subscriber ipv6-range { pool_name  | start_of_range }

  4. Remove the static IP address range configuration and trigger route deletion to the registered UPFs.

Deleting a Static IP Pool

This section describes the sequence of operations for deleting a static IP pool in SMF.

  1. To delete a static IP pool, it is first marked "offline".

  2. Reject new calls, which have the IP address assigned from the offline IP pool.

  3. Remove the existing subscribers. To remove the existing subscribers, run the following CLI commands:

    clear subscriber ipv4-pool pool_name 
clear subscriber ipv6-pool pool_name

  4. After all the subscribers are deleted, remove the IP pool configuration and trigger route deletion to the registered UPFs.

Removing Sx Association with an Offline UPF

This section describes the sequence of operations for removing association with an offline UPF.

  1. Set UPF as offline in profile-network-element-upf configuration.

    SMF stops selecting and associating dynamic IPs to the specific UPF for new sessions.

  2. NodeMgr receives configuration change notification about an offline UPF.

    SMF stops selecting and associating static IPs to the specific UPF for new sessions or associations.

  3. NodeMgr acknowledges the heart-beat messages for an already associated UPF.

  4. NodeMgr acknowledges the N4 association update from the UPF with release indication.

    This step does not impact the static and dynamic chunk allocations for IPAM.

    The IPAM module is unaware of the offline status for the UPF. It might include the offline UPF to add new IP pool or address ranges.

Sx Path Failure on UPF

This section describes the sequence of operations for Sx path failure on UPF.

  1. The NodeMgr initiates the clear subscriber command.

  2. The NodeMgr sends UnRegisterUpf to IPAM.

  3. IPAM releases any dynamic IP address ranges and moves it to free range list.

  4. IPAM retains any static IP address ranges for the UPF. Sx path failure does not impact static IP address mappings.

Limitations

The Static IP Support feature has the following limitations:

  • Change of a pool from dynamic to static, and from static to dynamic is not supported when the system is in running mode.

  • Addition or removal of UPF is not supported when the system is in running mode.

  • The address range split must be optimal based on the number of UPFs and number of addresses in the ranges.

    For example:

    If there are 2 UPFs and 1024 addresses specified in the range, then specify the per-dp-split-size as 512.

    If there are 3 UPFs and 1024 addresses, then specify the per-dp-split-size as 256.

  • When the system is running, the DNN cannot be removed from a UPF.

  • Changing dual-stack IPAM pool to single-stack or changing single-stack IPAM pool to dual-stack is not supported.

Configuring Static IP Support

To configure the Static IP Support feature, use the following sample configuration:

config 
   ipam 
      instance gr_instance_id 
         address-pool pool_name 
            static  
            end

NOTES:

  • ipam : Enter the IPAM configuration mode.

  • address-pool pool_name : Specify the name of the address pool to enter the pool configuration. pool_name must be a string.

  • static : Enable the static IP mode.

Statistics Support

The smf_service_resource_mgmt_stats and smf_service_node_mgr_stats provide details on static IP allocation type information.

The ip_req_type attribute in these statistics supports the following labels:

  • ip-static-subscription—Static IP allocation information based on subscription

  • ip-static-radius—Static IP allocation information based on RADIUS

Dual-stack Static IP Support Through IPAM

Feature Description

The SMF supports dual-stack static IP using IPAM. For dual-stack sessions, the AAA server sends both the IPv4 and IPv6 address prefixes as part of the Access-Accept message. In the SMF-IPAM configuration, both the IPv4 and IPv6 address prefixes are added in the same pool. The IPAM assigns both the IPv4 and IPv6 routes to a single UPF.

During the UPF selection, the Node Manager application uses the UPF for both the IPv4 and IPv6 addresses from the IPAM to handle them accordingly.

How it Works

The SMF supports dual-stack static IP through IPAM in the following ways:

  • Pool to UPF mapping—Based on the number of UPFs available, the IPv4 address ranges and IPv6 prefix ranges are split into smaller chunks. Then, the pair (chunk) is configured into the same IPAM pool.

    IPAM assigns all the addresses and prefixes that are configured in one dual-stack pool to a UPF in the manner they are received. The AAA server returns the dual-stack addresses from the same pair. From these addresses, SMF selects one UPF for dual-stack programming.

    The load-balancing of number of addresses and prefixes are managed. IPAM performs only the dual-stack static-pool to UPF mapping.

  • Address range no-split configuration—IPAM uses the "no-split" configuration to prevent the splitting of address ranges into smaller chunks. This configuration helps to prevent having multiple routes programming for a specific range.

The following table lists the errors or exceptions and how to handle them:

Table 8. Error and Exception Handling

Error or Exception

Exception Handling

IPv4 UPF and IPv6 UPF are configured incorrectly

  1. Select an active UPF. In case both the UPFs are active, select the UPF with the IPv4 address.

  2. Reset the IP information of the other stack and update the PDU session type accordingly.

IPv4 address is invalid or null

Select the UPF with IPv4 address and update the PDU session type accordingly.

IPv6 prefix is invalid or null

Select the UPF with IPv6 address and update the PDU session type accordingly.

IPv4 address and IPv6 prefix are invalid

Reject both the IPv4 address and IPv6 prefix.

Limitations

The Dual-stack Static IP Support feature has the following limitation:

  • The change in ‘no-split' configuration is not supported when the system is in running mode.

Configuring Dual-stack Static IP

This section describes how to configure the dual-stack static IP support using IPAM.

Configuring IPAM No-Split

To configure the IPAM no-split, use the following sample configuration:

config 
   ipam 
      instance gr_instance_id 
         address-pool pool_name 
         ipv4 
            split-size no-split 
            exit 
         ipv6 prefix_ranges 
            split-size no-split 
            exit 
         exit

NOTES:

  • split-size no-split : Prevent the IPv4 address ranges or IPv6 prefix ranges from splitting into smaller chunks.

IPAM Offline Mode Support

Feature Description

The SMF supports the addition of a dynamic pool, IPv4, or IPv6 address-range to a dynamic pool by default. The new chunks are added to the respective tags, such as DNN, and are assigned from the same pool.

To delete a dynamic pool or an IPv4 or IPv6 address range from a dynamic pool:

  1. Configure the pool or address range as offline. The IPAM then stops assigning addresses from the respective pool or address range.

  2. Use the following clear subscriber CLI commands to delete the subscribers based on respective pool or address range that are configured to offline mode:

    • clear subscriber ipv4-pool pool_name

    • clear subscriber ipv4-range pool_name/start_of_range

    • clear subscriber ipv6-pool pool_name

    • clear subscriber ipv6-range pool_name/start_of_range

  3. Use the following cdl show CLI commands and wait until all the subscribers are deleted:

    • cdl show sessions count summary filter { key ipv4-pool: pool_name condition match }

    • cdl show sessions count summary filter { key ipv4-range: pool_name/start_of_range condition match }

    • cdl show sessions count summary filter { key ipv6-pool: pool_name condition match }

    • cdl show sessions count summary filter { key ipv6-range: pool_name/start_of_range condition match }

    • cdl show sessions count summary slice-name slice_name

  4. After all the subscribers are deleted, delete the pool or address range from the IPAM configuration.

Configuring the IPAM Offline Mode

This section describes how to configure the IPAM offline feature for pool, IPv4 address range, and IPv6 prefix ranges.

Configuring Pool to Offline Mode

To configure the entire pool to offline mode, use the following sample configuration:

config 
   ipam 
      instance gr_instance_id 
         address-pool pool_name 
            offline 
            end

NOTES:

  • address-pool pool_name : Specify the name of the pool to enter the pool configuration. pool_name must be a string.

  • offline : Configure the pool to offline mode.

Setting IPv4 Address Range to Offline Mode

To configure the IPv4 address range to offline mode, use the following sample configuration:

config 
   ipam 
      instance gr_instance_id 
         address-pool pool_name 
            vrf-name vrf_name 
            ipv4 
               address-range start_ipv4_address end_ipv4_address offline 
               end

NOTES:

  • address-pool pool_name : Specify the name of the pool to enter the pool configuration. pool_name must be a string.

  • ipv4 : Enter the IPv4 mode.

  • address-range start_ipv4_address end_ipv4_address offline : Specify the IP addresses for the start and end IPv4 address range.

    • offline : Set the selected address range to offline mode.

Setting IPv6 Prefix Ranges to Offline Mode

To configure IPv6 prefix range to offline mode, use the following sample configuration:

config 
   ipam
      instance gr_instance_id 
         address-pool pool_name 
         vrf-name vrf_name 
            ipv6 
               prefix-ranges 
                  prefix-range  prefix_valuelength prefix_lengthoffline 
                  end

NOTES:

  • address-pool pool_name : Specify the name of the pool to enter the pool configuration. pool_name must be a string.

  • ipv6 : Enter the IPv6 mode.

  • prefix-ranges : Enter the prefix ranges mode.

  • prefix-range prefix_value length prefix_length offline : Specify the prefix range and prefix length of the IPv6 prefix range.

    • offline : Set the selected address range to offline mode.

IPAM Redundancy Support Per UPF

Feature Description

The SMF supports IPAM redundancy and load balancing for each UPF. The IPAM running in the Node Manager microservice has two IPAM instances that are associated to each UPF. When one IPAM instance is inactive, the other IPAM instance manages the address allocation requests for the UPF.

How it Works

This section provides a brief of how the IPAM redundancy support per UPF feature works.

  • Peer Selection—The Node Manager peer is selected during the UPF association.

  • UPF Registration with Peer IPAM—IPAM is notified with the instance ID of the peer for the UPF during the registration of the UPF call. IPAM allocates routers from the local data for the specific DNN and checks if the peer IPAM instance is in active or inactive state.

    If the peer IPAM instance is active, a REST call is sent to it to register to the same UPF in the local instance and to receive the routes as response.

    If the peer IPAM instance is inactive, the local instance takes over the IPAM context of the remote instance. Then, the local instance registers to the UPF, receives the routes, and keeps the data back in the cache pod. After the peer instance is active, it restores the same data from the cache pod.

    Routes from both the instances are sent to UPF for load-balanced address allocations from both the instances.

  • Address Allocation in Load-Balanced Model—As one UPF is registered to two IPAM servers, SMF sends the address allocation requests to any peer that is load-balanced. Respective IPAM instances assign new addresses from their local address bitmap. If one peer instance is inactive, the other peer instance handles all the requests.

  • Address Release Request Handling—In IPAM, the Address Release request is sent to the instance that had allocated the IP the first time. If that peer is inactive, the Address Release request is sent to the peer IPAM.

    The IPAM instance that receives the address releases for remote instances, keeps buffering these instances locally and updates the cache pod periodically. After the remote peers are active, they handle the buffered address release requests.

  • Release of the UPF—When a peer IPAM is active during the release of a UPF, a REST call is sent to clear the data. If the peer IPAM is inactive, the existing IPAM instance takes over the operational data of the remote IPAM, clears the UPF information, and updates the cache pod.

IPAM Quarantine Timer

Feature Description

The IPAM Quarantine Timer Support feature supports the IPAM quarantine timer for the IP pool address. This feature keeps the released IP address busy until the quarantine timer expires to prevent the reuse of that IP address. Each IP pool must be configured with a timer value. This value determines the duration of a recently released address to be in the quarantine state before it is available for allocation. After the timer expires, the IP address is available in the list of free addresses for allocation by the subscriber. A released IP address with no address quarantine timer is considered to be in use for allocation. If a subscriber attempts to reconnect when the address quarantine timer is armed even if it is the same subscriber ID, the subscriber does not receive the same IP address.

Configuring IPAM Quarantine Timer

This section describes how to configure the IPAM quarantine timer.

Configuring IPAM Quarantine Timer

This section describes how to configure the IPAM quarantine timer.

config 
   ipam instanceinstance_id 
      address-pool pool_name 
         address-quarantine-timer quarantine_timer_value 




         end

NOTES:

  • address-pool pool_name —Specifies the name of the pool to enter the pool configuration. pool_name must be the name of the address pool.

  • address-quarantine-timer quarantine_timer_value —Specifies the value of the quarantine timer in seconds. quarantine_timer_value must be in the range of 4-3600 seconds. The default value is 4.

IP Address Validation with CDL Configuration

This section describes how to validate IP Address with CDL configurtation.

System Diagnostics IP Validation

This section describes how to enable/disable System Diagnostics IP Validation.

config 
   system-diagnostics ip-validation enable ignore-mismatch-responses  
   exit

NOTES:

system-diagnostics ip-validation ignore-mismatch-responses — Ignores any CDL inconsistencies during address validation.

IP validation ignore mismatch responses is meant for avoiding duplicate IPs. If this feature is enabled, SMF Nodemgr checks if the current IP is already used by any other records in CDL. If no records are found, then IP address is assigned to the UE. If CDL record is found, then a new IP is assigned to the UE.


Important

Enabling validation ignore mismatch responses may have certain performance impact.

Statistics

nodemgr_diag_ip_verify

Description: Display Nodemgr to CDL IP-Validation query related statistics

Metrics-Type: Counter

Query: sum(nodemgr_diag_ip_verify{namespace="$namespace"}) by (status)

Labels:

Label: status

Value: success | duplicate_record_found | cdl_ipc_failure | ipv4_alloc_failed | ipv6_alloc_failed | unknown

  • success Record not found in CDL

  • duplicate_record_found Duplicate record found in CDL

  • cdl_ipc_failure Search IPC request to CDL failed

  • ipv4_alloc_failed IPV4 address-request failed, unable to get free-IP, twice

  • ipv6_alloc_failed IPV6 prefix-request failed, unable to get free-IP, twice

  • unknown IPC request to CDL failed twice, give-up and return the IP to smf-service

IPAM_Quarantine_Statistics

Description: Display IPAM Quarantine IP Batch related statistics

Metrics-Type: Counter

Query: sum(IPAM_Quarantine_Statistics{namespace="$namespace"}) by (addressType, type)

Labels:

Label: pool

Value: <name-of-pool>

Label: upf

Value: <name-of-upf>

Label: addressType

Value: IPv4 | IPv6PD

Label: type

Value: start_batch_qsize | end_batch_qsize | pop_count_qtime | pop_count_qsize | avg_qtime_secs

  • start_batch_qsize - Number of IPs in QT-queue at the start of batch processing

  • end_batch_qsize - Number of IPs in QT-queue at end of batch processing

  • pop_count_qsize - Number of IPs removed from QT-queue due to qsize limit

  • pop_count_qtime - Number of IPs removed from QT-queue due to qtime limit

  • avg_qtime_secs - Average time-in-seconds the IPs were in QT-queue before removing

Configuring IPAM Quarantine Qsize

This section describes how to configure the IPAM quarantine queue size support feature.

Configuring IPAM Quarantine Queue Size

This section describes how to configure the IPAM quarantine timer.

config 
   ipam instanceinstance_id 
      address-pool pool_name 
         address-quarantine-qsize quarantine_queue_size 
         exit 
        exit

NOTES:

  • ipam —Enter the IPAM configuration.

  • address-pool pool_name —Specifies the name of the pool to enter the pool configuration. pool_name must be the name of the address pool.

  • address-quarantine-qsize quarantine_queue_size —Specifies the value of the quarantine queue size. The default value is 0.

    During QT processing, excess IP addresses in quarantine-queue are released to Free-list irrespective of quarantine-timer expiry by force.

Overlapping IP Address Pools

Feature Description

The Overlapping IP Address Pools feature improves flexibility in assigning IP addresses dynamically. This feature allows you to configure overlapping IP address pool groups to create different address spaces and concurrently use the same IP addresses in different address spaces.

You can configure overlapping IP address range across different pools with unique DNN and VRF type.

Configuring Overlapping IP Address Pools

Use the following example configuration to configure overlapping static IP address pools.

config
ipam instance instance_id 1 
source local
address-pool pool1
  static
  vrf-name vrf1@ISP
  tags
   dnn dnn1
  exit
  ipv4
   split-size
    per-cache 256
    per-dp    256
   exit
   address-range 209.165.200.225 209.165.200.254
  exit
exit
address-pool pool2
  static
  vrf-name vrf2@ISP
  tags
   dnn dnn2
  exit
  ipv4
   split-size
    per-cache 256
    per-dp    256
   exit
   address-range 209.165.200.225 209.165.200.254
  exit
exit
exit

The following is an example configuration for overlapping IP address pools.

config
ipam instance instance_id 1 
source local
address-pool pool1
  vrf-name vrf1@ISP1
  tags
   dnn dnn1
  exit
  ipv4
   split-size
    per-cache 256
    per-dp    256
   exit
   address-range 209.165.200.225 209.165.200.254
  exit
exit
address-pool pool2
  vrf-name vrf2@ISP2
  tags
   dnn dnn2
  exit
  ipv4
   split-size
    per-cache 256
    per-dp    256
   exit
   address-range 209.165.200.225 209.165.200.254
  exit
exit
exit

Virtual Routing and Forwarding Function

Feature Description

Different mobile virtual network operators (MVNOs) have the same IP address range in the deployment. The SMF supports this functionality using the Virtual Routing and Forwarding (VRF) configuration, where the same IP address range can exist in different VRFs. In such cases, IP pool configuration includes the VRF name. In these scenarios, the SMF sends IP address chunk details along with the configured VRF name to UPF. This helps UPF to map the IP address to VRF configured within UPF.

Configuring VRF

This section describes how the SMF configures the VRF.

Configuring VRF Name

Enable VRF name in the configuration of address pool. When “vrf-name” in the IP pool is configured with “@” character, the first part before “@” is treated as “VRF” name which is sent to UPF and the second part after “@” is sent as context name in N4 Association Update message.

When “vrf-name” in the IP pool is configured without “@” character, the entire name is sent as context name (existing behaviour) in N4 Association Update message.

The SMF sends the VRF name in N4 Session Establishment request if it is configured with “@” in the pool in “UE IP VRF” IE.

Use the following configuration to configure the VRF name:

config 
   ipam  instanceinstance_id 
      address-pool pool_name  
         vrf-name vrf_name 
         end

NOTES:

  • ipam : Enters the IPAM configuration mode.

  • address-pool pool_name : Configures the address pool configuration. pool_name must be the name of the address pool.

  • vrf-name vrf_name : Specifies the name of the VRF for the pool.

Troubleshooting Information

This section provides information on using the command line interface (CLI) commands, alerts, logs, and metrics for troubleshooting issues that may arise during system operation.

Range of IPv6 Allocated to UPF

The show ipam dp dp_name ipv6-prefix CLI command displays the IP pool chunks allocated to UPF. This pool chunk includes the VRF tag information and details, such as whether the pool defined is a static or dynamic pool. 

[unknown] smf# show ipam dp 198.18.1.3 ipv6-prefix  

===================================================================================
Flag Indication: S(Static) O(Offline)
N/P  Indication: N(Native InstId) P(Peer InstId)
=============================================================================================================================
StartAddress          EndAddress             AllocContext       Route                    N/P    Utilization   Flag 
===================================================================================
3001:db0::            3001:db0:0:3fff::      v6pool4(vrf4@ISP)  3001:db0::/50            -                    S
3001:db0::            3001:db0:0:3fff::      v6pool3(vrf3@ISP)  3001:db0::/50            -                    S
3001:db0:0:4000::     3001:db0:0:7fff::      v6pool4(vrf4@ISP)  3001:db0:0:4000::/50     -                    S
3001:db0:0:4000::     3001:db0:0:7fff::      v6pool3(vrf3@ISP)  3001:db0:0:4000::/50     -                    S
===================================================================================
[unknown] smf#

Range of IPv4 Allocated to UPF

The show ipam dp dp_name ipv4-addr CLI command displays the IP pool chunks allocated to UPF. This pool chunk includes the VRF tag information and details, such as whether the pool defined is a static or dynamic pool. 

[unknown] smf# show ipam dp 209.165.201.3 ipv4-addr  

==========================================================================================
Flag Indication: S(Static) O(Offline)
N/P  Indication: N(Native InstId) P(Peer InstId)
====================================================================================================
StartAddress     EndAddress         AllocContext       Route               N/P   Utilization   Flag 
====================================================================================================
209.165.200.129  209.165.202.131    v4pool3(vrf3@ISP)209.165.200.129/27      -                  -S
209.165.200.129  209.165.202.131    v4pool4(vrf4@ISP)209.165.200.129/27      -                  -S
209.165.200.253  209.165.202.153    v4pool3(vrf3@ISP)209.165.200.253/27      -                  -S
209.165.200.253  209.165.202.153    v4pool4(vrf4@ISP)209.165.200.253/27      -                  -S
209.165.202.154  209.165.202.155    v4pool3(vrf3@ISP)209.165.202.154/27      -                  -S
209.165.202.154  209.165.202.155    v4pool4(vrf4@ISP)209.165.202.154/27      -                  -S
209.165.202.156  209.165.202.156    v4pool3(vrf3@ISP)209.165.202.156/27      -                  -S
209.165.202.156  209.165.202.156    v4pool4(vrf4@ISP)209.165.202.156/27      -                  -S
209.165.202.128  209.165.202.158    v4pool4(vrf4@ISP)209.165.202.128/27      -                  -S
209.165.202.129  209.165.202.158    v4pool4(vrf4@ISP)209.165.202.129/27      -                  -S
209.165.200.225  209.165.200.253    v4pool4(vrf4@ISP)209.165.200.225/27      -                  -S
209.165.201.134  209.165.201.30     v4pool4(vrf4@ISP)209.165.201.134/27      -                  -S
====================================================================================================

IP Pool Mapping Error Logs

The following is a sample error log for incorrect static IP to pool mapping or if static IP received from RADIUS is not found with any UPF. 

[smf-service-n0-0] 2020/09/23 07:42:25.969 smf-service [DEBUG] [rmgrutil.go:501] [smf-service.smf-app.resource] [imsi-123456789012345:5] [imsi-123456789012345:5] [16] response received for message NmgrRersourceMgmtResponse 
[smf-service-n0-0] 2020/09/23 07:42:25.969 smf-service [INFO] [upmgrCacheApi.go:450] [misc-lib.upmgrcache.gen] Cache doesnot have entry for UpfEpKey:  
[smf-service-n0-0] 2020/09/23 07:42:25.969 smf-service [ERROR] [rmgrutil.go:73] [smf-service.smf-app.resource] [imsi-123456789012345:5] [imsi-123456789012345:5] [16] Both the associated nodemgr instances for upfEpKey:  is down 
[smf-service-n0-0] *errors.errorString Both the associated nodemgr instances for upfEpKey:  is down 
[smf-service-n0-0] /opt/workspace/smf-service/src/smf-service/vendor/wwwin-github.cisco.com/
mobile-cnat-golang-lib/app-infra.git/src/app-infra/infra/Transaction.go:621 (0xd8b29e) 
[smf-service-n0-0] /opt/workspace/smf-service/src/smf-service/procedures/generic/rmgrutil.go:73 (0x14dbd61)