The following illustration provides an overview of Nexthop Forwarding feature.

You can configure Nexthop IP address at the SMF under DNN profile or IPAM profile. During PDU Establishment, the SMF relays the IPv4/IPv6 address over the N4 interface in the NEXT HOP IP private IE in a PFCP Session Establishment Request.

You can also configure Nexthop IP address at the UPF through Charging-Action.

Note	When Nexthop address is provided by both SMF and UPF Charging-Action, the UPF Charging-Action Nexthop address takes precedence.

Configuration Priority

Configuration Use Cases

Interface

The following Private IEs are introduced in Sx/N4 Session Establishment message.

The following is a sample output of SX_SESSION_ESTABLISHMENT_REQUEST in which the SMF relays the Nexthop IP to the UPF.

CREATE FAR:
  Type: 3
  Value:
   FAR ID:
     Type: 108
     Value: 0x80000002
   APPLY ACTION:
     Type: 44  
     Value:
       DROP: 0
       FORW: 1 
       BUFF: 0
       NOCP: 0
       DUPL: 0
   FORWARDING PARAMETERS:
     Type: 4
     Value:
       DESTINATION INTERFACE:
         Type: 42
         Value: CORE (1)
       PDN INSTANCE:
          Type: 22
          Value: intershat
          INNER PACKET MARKING:
            Type: 220
            TOS/TRAFFIC CLASS: 0xB8 0xFC
    NextHop ID:
      Value: 0x0001 

CREATE TRAFFIC ENDPOINT: 
    Type: 127  Length: 20
    Value:               
    Traffic Endpoint ID: 
        Type: 131  Length: 1
        Value: 0x0004       
        Hex: 0083 0001 04   
        Local F-TEID:       
            Type: 21  Length: 1
            Value:             
                CH: 1          
                IPv4: 0        
                IPv6: 0        
                CHID: 0        
            Hex: 0015 0001 04  
        Bearer Info:           
            Type: 225  Length: 6
            QCI: 5              
            ARP: 84             
            Charging ID: 5592407
            Hex: 00E1 0006 0554 0055 5557 
    Hex: 007F 0014 0083 0001 0400 1500 0104 00E1 
                 0006 0554 0055 5557                     
 NEXT HOP IP: 
    Type: 237  Length: 14
    Value:               
    NextHop ID:          
        Type: 238  Length: 1
        Value: 0x0001       
        Hex: 00EE 0001 01   
    IP ADDR:                
        Type: 239  Length: 5
        Value:              
            IPv4: 1                 
            IPv6: 0
            IPv4: 209.165.202.150
            IPv6:            
            Hex: 00EF 0005 020F 0F0F 0F
    Hex: 00ED 000E 00EE 0001 0100 EF00 0502 0F0F 
         0F0F
 

The following are the known limitations to this feature in this release:

• Currently, configuring Nexthop forwarding through AAA isn’t supported.

• IPv6 configuration from SMF via IPAM profile isn’t supported.

• Nexthop address sent on RADIUS and Diameter (Redirect information from PCF) interfaces isn’t qualified.

• When you configure Nexthop forwarding in DNN profile and IPAM, next hop is only seen in Sx Establishment, and not in Create FAR IE of Sx Session Modification Request.

At the UPF, use the following CLI commands to configure Nexthop Forwarding through Charging Action.

configure 
   active-charging service service_name  
      charging-action charging_action_name 
         nexthop-forwarding-address ipv4_address/ipv6_address 

NOTES:

• charging-action charging_action_name: Specifies the name of a charging action. charging_action_name must be an alphanumeric string of 1–63 characters and can contain punctuation characters. Each charging action must have a unique name.

• nexthop-forwarding-address ipv4_address/ipv6_address: Configures the nexthop forwarding address.

At the SMF, use the following CLI commands to configure Nexthop Forwarding through DNN profile.

configure 
   profile dnn intershat  
         nexthop-forwarding-address { ipv4 ipv4_address| ipv6  ipv6_address } 
         end 

NOTES:

• nexthop-forwarding-address { ipv4 ipv4_address | ipv6 ipv6_address } : Configures the Nexthop Forwarding address.

  • ipv4_address : Configures IPv4 address.

  • ipv6_address : Configures IPv6 address (supports colon-separated hexadecimal notation).

At the SMF, use the following CLI command to configure Nexthop Forwarding at IP pool through IPAM profile.

address-range start_address end_address nexthop-forwarding-address ipv4_address 

NOTES:

• address-range start_address end_address nexthop-forwarding-address ipv4_address : Configures the IPv4 address as Nexthop Forwarding address for this IP pool.

This section provides information about show commands and their outputs in support of this feature.

show subscriber user-plane-only full all

The output of this show command is enhanced to include the following fields introduced in support of this feature.

• Next Hop Ip Address - Displays the configured Nexthop IP address.

Note	Next Hop Ip Address field is displayed only if the Nexthop IP address is relayed from the SMF. This field is not displayed if Nexthop IP address is configured only at the UPF using Charging-Action.