The SMF sends unsolicited router advertisement on successful PDU Session Establishment to share the allocated IPv6 prefix to UE. RA message is sent over the GTPU tunnel, which is created between SMF and UPF during the session establishment procedure. SMF also installs PDRs and FARs on the UPF to enable routing for RS and RA messages.

Note	The UPF cannot generate or send the unsolicited router advertisement to the UE as the IPv6 prefix allocation is performed by SMF.

To get the allocated IPv6 prefix, UE sends a router solicit message. Upon receiving the router solicit message, SMF sends the router advertisement message containing the allocated UE IPv6 prefix towards UE.

To configure the Router Advertisement parameters, use the following sample configuration:

config 
   profile icmpv6 icmpv6profile_name 
      options { hop-limit hop_limit | mtu mtu_size | reachable-time reachable_time | retrans-timer retrans_timer | router-lifetime router_lifetime | virtual-mac virtual_mac } 
      ra trigger handover { false | true } 
      end 

NOTES:

• profile icmpv6 icmpv6profile_name : Specify the ICMPv6 profile name. icmpv6profile_name must be an alphanumeric string.

• options { hop-limit hop_limit | mtu mtu_size | reachable-time reachable_time | retrans-timer retrans_timer | router-lifetime router_lifetime | virtual-mac virtual_mac } : Configure the ICMPv6 options.

  • hop-limit hop_limit : Configure the hop limit. hop_limit must be an integer in the range of 0–255. Default: 255.

  • mtu mtu_size : Configure the MTU size. Default: 1500.

    mtu_size must be an integer in the range of 1280-1500.

  • reachable-time reachable_time : Configure the reachable time in milliseconds. Default: 0.

    reachable_time must be an integer in the range of 0-3600.

  • retrans-timer retrans_timer : Configure the retransmission timer in milliseconds. Default: 0.

    retrans_timer must be an integer in the range of 0-4294968.

  • router-lifetime router_lifetime : Configure the router lifetime in seconds. router_lifetime must be an integer in the range of 0–65535. Default: 65535.

  • virtual-mac virtual_mac : Configure the local virtual MAC address.

• ra trigger handover { false | true } : Configure the trigger to send router advertisements for Wi-Fi handovers.

Verifying the Configuration

Use the show running-config profile icmpv6 command to verify the Router Advertisement configuration.

The following configuration is an example output of the command:

[unknown] smf(config)# show running-config profile icmpv6 
profile icmpv6 icmpprf1
 options hop-limit 255
 options mtu   1500 
 options reachable-time 0
 options retrans-timer 0
 options router-lifetime 65535
 options virtual-mac b6:6d:57:45:45:45
 ra trigger handover true
exit 

To configure the remote virtual MAC address in the DNN profile, use the following sample configuration:

config 
   profile dnn dnnprofile_name 
      virtual-mac mac_address 
      exit 

NOTES:

• profile dnn dnnprofile_name : Specify the DNN profile name. dnnprofile_name must be an alphanumeric string.

• virtual-mac mac_address : Specify the remote virtual MAC address used to generate interface ID for UE. mac_address must be a string in the MAC address pattern.

In release 2021.01 and later, the SMF generates unique 64-bit interface ID which is non-EUI-64 format by using SBI VIP address and CommonId of the subscriber.

That is, IPv6 interface ID = VIP-IP (4 bytes) + CommonId (4 bytes)

By default, virtual-mac CLI command is now disabled under DNN configuration.

To associate the ICMPv6 profile with the SMF service profile, use the following sample configuration:

config 
   profile smf smfprofile_name 
      service name svc_name 
         icmpv6-profile icmpv6profile_name 
         exit 

NOTES:

• profile smf smfprofile_name : Specify the SMF service profile name. smfprofile_name must be an alphanumeric string.

• service name svc_name : Specify the name of the SMF network function service. svc_name must be an alphanumeric string.

• icmpv6-profile icmpv6profile_name : Specify the load profile name to associate with the SMF service profile. icmpv6profile_name must be an alphanumeric string.