The following configurations are required on the RADIUS server to differentiate between a GTPv1 subscriber and a GTPv2 subscriber:

subscriber-profile profile1 { # this is a GTPv2 profile 
access-accept { 
reply-msg "Default profile" 
cisco-avpair { "cisco-mn-service=ipv4" } 
cisco-avpair { "cisco-mpc-protocol-interface=gtpv2" } 
cisco-avpair { "cisco-service-selection=example.com" } 
cisco-avpair { "cisco-msisdn=4910000000" } 
3gpp { 
imsi 406091000000000 
} 
} 
} 
subscriber-profile profile2 { # this is a GTPv1 profile
access-accept { 
reply-msg "Default profile" 
cisco-avpair { "cisco-mn-service=ipv4" } 
cisco-avpair { "cisco-mpc-protocol-interface=gtpv1" } 
cisco-avpair { "cisco-service-selection=example.com" } 
cisco-avpair { "cisco-msisdn=4900000000" } 
3gpp { 
imsi 406090000000000 
} 
} 
} 
sub-grp-mgr sub-grp1 { 
control-by round-robin 
group-profiles { 
subscriber-profile profile1 profile-priority 99 
subscriber-profile profile2 profile-priority 98 
} 
}

The initiator unclassified mac-address command must be configured on every iWAG access interface to support subscriber roaming between these interfaces. As shown in the following configuration, all the access interfaces must be specified under the GTP configuration before bringing up the IP subscriber sessions. If the access interface is not specified under the GTP, a subscriber’s roaming option is not enabled for that interface. Also, adding interfaces under the GTP after the sessions bring up fails subscriber roaming.

The following example shows the configuration for GTPv1 and GTPv2 roaming scenario:

interface GigabitEthernet0/0/2 
description To client facing interface 
ip address 192.1.1.1 255.255.0.0 
negotiation auto 
service-policy type control ISG_GTP_CONTROL 
ip subscriber l2-connected 
initiator unclassified mac-address # must for roaming config 
initiator dhcp 
! 
interface GigabitEthernet0/0/3 
description To client facing interface
ip address 192.2.1.1 255.255.0.0 
negotiation auto 
service-policy type control ISG_GTP_CONTROL 
ip subscriber l2-connected 
initiator unclassified mac-address # must for roaming config 
initiator dhcp 
!
gtp
  n3-request 3
  interval t3-response 10
  interval echo-request 64
  information-element rat-type wlan
  interface local GigabitEthernet1/3/0
  apn 1200
         apn-name example.com
         ip address ggsn 98.0.7.13
         default-gw 192.168.0.1 prefix-len 16
         dns-server 192.168.255.253
         dhcp-lease 3000
  interface access GigabitEthernet0/0/2
  interface access GigabitEthernet0/0/3