I am doing NAT from IPv6 to IPv4 on GGSN, from log it can translated from IPv6 to IPv4 normally:
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SAMI 3/4: Nov 19 05:29:30.006: IPv6 NAT: IPv6->IPv4:
src (2001:236::CDC8:1D93:7CA6:58B1 -> 10.100.112.8)
dst (2002::7D8D:1FA0 -> 125.141.31.160)
ref_count = 1, usecount = 0, flags = 2,
rt_flags = 0, more_flags = 0
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And we can see from wireshark trace the pinging can reach this server and also server reply to GGSN but we can see the reply loop back to server:
We suspect it is not NAT back from IPv4 to IPv6 then it routing the traffic on IPv4 which using the default route on GGSN and that cause the loop.
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GGSN3#show ip route
Gateway of last resort is 192.168.3.250 to network 0.0.0.0
172.26.0.0/16 is variably subnetted, 9 subnets, 3 masks
S 172.26.5.0/26 [1/0] via 172.26.10.250
C 172.26.10.0/24 is directly connected, GigabitEthernet0/0.20
C 172.26.5.67/32 is directly connected, Loopback0
O 172.26.5.66/32 [110/2] via 172.26.10.151, 1d05h, GigabitEthernet0/0.20
O 172.26.5.65/32 [110/2] via 172.26.10.141, 1w2d, GigabitEthernet0/0.20
O 172.26.5.70/32 [110/2] via 172.26.10.153, 1d05h, GigabitEthernet0/0.20
O 172.26.5.69/32 [110/2] via 172.26.10.143, 1w2d, GigabitEthernet0/0.20
O 172.26.5.68/32 [110/2] via 172.26.10.152, 1d05h, GigabitEthernet0/0.20
O 172.26.5.72/32 [110/2] via 172.26.10.154, 1d05h, GigabitEthernet0/0.20
C 192.168.3.0/24 is directly connected, GigabitEthernet0/0.16
S* 0.0.0.0/0 [1/0] via 192.168.3.250
GGSN3#
GGSN3#show ipv6 route
IPv6 Routing Table - Default - 6 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
B - BGP, M - MIPv6, R - RIP, D - EIGRP
EX - EIGRP external
O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
S ::/0 [1/0]
via 2000:2:2:2:2:2:2:1112
C 2000:2:2:2:2:2:2:0/112 [0/0]
via GigabitEthernet0/0.113, directly connected
L 2000:2:2:2:2:2:2:1115/128 [0/0]
via GigabitEthernet0/0.113, receive
C 2001:236::/64 [0/0]
via Virtual-Access5.1, directly connected
S 2001:236::CDC8:1D93:7CA6:58B1/128 [1/0]
via Virtual-Access5.1, directly connected
L FF00::/8 [0/0]
via Null0, receive
GGSN3
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Our configuration as in attached file.
Please help if something wrong or missing in the configuraiton??
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