I have NAT64 configured on a Cisco ASR1002 router using the prefix 2c0f:6400:0:1::/96 and an IPv4 pool ranging from 41.216.172.97 to 41.216.172.127. It's set up to translate DNS64-resolved IPv6 requests for IPv4-only services.
Issue:
NAT64 works initially, but suddenly stops translating after some time. It starts working again after some period
Only some IPv4 sites are reachable from my IPv6 network. Even when the translation is working, some v4 sites are still not reachable.
Restarting the router or clearing NAT sometimes helps temporarily.
Has anyone experienced similar behavior with NAT64 on the ASR1000 series? What troubleshooting steps or fixes would you recommend? Could this be an IOS XE bug or a resource exhaustion issue?
Appreciate any insights or known workarounds.
Below is my Show run output>>
NAT64#sh run
Building configuration...
Current configuration : 3065 bytes
!
! Last configuration change at 08:38:17 UTC Fri Apr 4 2025 by sodiq
!
version 15.5
service timestamps debug datetime msec
service timestamps log datetime msec
no platform punt-keepalive disable-kernel-core
!
hostname NAT64
!
boot-start-marker
boot-end-marker
!
!
vrf definition Mgmt-intf
!
address-family ipv4
exit-address-family
!
address-family ipv6
exit-address-family
!
!
no aaa new-model
!
!
!
!
!
!
!
!
!
!
!
ip name-server 2C0F:6400:C00:1::53 8.8.8.8
ip domain name vdtcomms.com
!
!
!
ipv6 unicast-routing
!
!
!
!
!
!
!
subscriber templating
!
multilink bundle-name authenticated
!
!
!
!
!
!
!
!
!
license udi pid ASR1002-X sn JAE214205YD
license accept end user agreement
!
spanning-tree extend system-id
!
!
redundancy
mode none
!
!
!
!
interface Loopback0
ip address 41.216.160.253 255.255.255.255
ip ospf 100 area 0.0.0.0
ipv6 address 2C0F:6400::19/128
!
interface GigabitEthernet0/0/0
no ip address
negotiation auto
!
interface GigabitEthernet0/0/1
no ip address
negotiation auto
!
interface GigabitEthernet0/0/2
mtu 4000
no ip address
negotiation auto
!
interface GigabitEthernet0/0/2.3099
encapsulation dot1Q 3099
ipv6 address 2C0F:FC98:501:6::2/126
!
interface GigabitEthernet0/0/3
description interface facing ipv4
mtu 2000
ip address 41.216.160.106 255.255.255.252
ip ospf network point-to-point
ip ospf 100 area 0.0.0.0
ip ospf cost 7000
negotiation auto
ipv6 address 2C0F:6400:400:6::3/127
ipv6 enable
nat64 enable
ipv6 ospf 100 area 0
!
interface GigabitEthernet0/0/4
no ip address
negotiation auto
!
interface GigabitEthernet0/0/5
description interface facing ipv6
mtu 2000
ip address 41.216.172.98 255.255.255.224
ip ospf network point-to-point
ip ospf 100 area 0.0.0.0
negotiation auto
ipv6 address 2C0F:6400:400:1::3/127
ipv6 enable
nat64 enable
ipv6 ospf 100 area 0
ipv6 ospf network broadcast
!
interface GigabitEthernet0
vrf forwarding Mgmt-intf
no ip address
shutdown
negotiation auto
!
router ospfv3 100
router-id 41.216.160.253
!
address-family ipv6 unicast
exit-address-family
!
router ospf 100
router-id 41.216.160.253
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server
ip tftp source-interface GigabitEthernet0
ip route 41.216.172.96 255.255.255.224 Null0
ip ssh version 2
!
ipv6 route 2C0F:6400::/32 Null0 25
!
!
!
ipv6 access-list NAT64-ACL
permit ipv6 2C0F:6400::/32 any
!
control-plane
!
!
!
!
!
!
!
!
!
!
line con 0
stopbits 1
line aux 0
stopbits 1
line vty 0 4
login local
transport input ssh
!
nat64 prefix stateful 2C0F:6400:0:1::/96
nat64 v4 pool PREFIX_4 41.216.172.99 41.216.172.127
nat64 v6v4 list NAT64-ACL pool PREFIX_4 overload
!
!
end
NAT64#
