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NAT-PT v4-mapped and IPv4 overload.

I'm trying to get NAT-PT using v4-mapped to work with overload.  The following works:

ipv6 route ::/0 2000::1

ipv6 nat v6v4 source list v4-map-list pool v4NATpool

ipv6 nat v6v4 pool v4PATpool 192.168.178.100 192.168.178.100 prefix-length 24

ipv6 nat v6v4 pool v4NATpool 192.168.178.101 192.168.178.110 prefix-length 24

ipv6 nat prefix 2001::/96 v4-mapped v4-map-list

!

ipv6 access-list v4-map-list

permit ipv6 any 2001::/96

The following does not:

ipv6 route ::/0 2000::1

ipv6 nat v6v4 source list v4-map-list pool v4PATpool overload

ipv6 nat v6v4 pool v4PATpool 192.168.178.100 192.168.178.100 prefix-length 24

ipv6 nat v6v4 pool v4NATpool 192.168.178.101 192.168.178.110 prefix-length 24

ipv6 nat prefix 2001::/96 v4-mapped v4-map-list

!

ipv6 access-list v4-map-list

permit ipv6 any 2001::/96

When debug ipv6 nat det is turned on the overloaded config gets:

R11#debug ipv6 nat det

IPv6 NAT-PT detailed debugging is on

R11#

*Mar  1 00:06:15.651: IPv6 NAT: address allocated 192.168.178.100

*Mar  1 00:06:15.651: IPv6 NAT: Dropping v6tov4 packet

*Mar  1 00:06:16.667: IPv6 NAT: address allocated 192.168.178.100

*Mar  1 00:06:16.671: IPv6 NAT: Dropping v6tov4 packet

*Mar  1 00:06:17.675: IPv6 NAT: address allocated 192.168.178.100

*Mar  1 00:06:17.675: IPv6 NAT: Dropping v6tov4 packet

*Mar  1 00:06:18.667: IPv6 NAT: address allocated 192.168.178.100

*Mar  1 00:06:18.667: IPv6 NAT: Dropping v6tov4 packet

*Mar  1 00:06:19.675: IPv6 NAT: address allocated 192.168.178.100

*Mar  1 00:06:19.675: IPv6 NAT: Dropping v6tov4 packet

Remove overload, and it works just fine:

R11(config)#no ipv6 nat v6v4 source list v4-map-list pool v4PATpool overload

R11(config)#ipv6 nat v6v4 source list v4-map-list pool v4NATpool        

R11(config)#end

R11#

*Mar  1 00:06:54.687: %SYS-5-CONFIG_I: Configured from console by console

*Mar  1 00:06:58.411: IPv6 NAT: address allocated 192.168.178.101

*Mar  1 00:06:58.411: IPv6 NAT: icmp src (2000::1) -> (192.168.178.101), dst (2001::C0A8:B208) -> (192.168.178.8)

*Mar  1 00:06:59.411: IPv6 NAT: ipv6nat_find_entry_v4tov6:

     ref_count = 1,

                                usecount = 0, flags = 2, rt_flags = 0,

                                more_flags = 0

*Mar  1 00:06:59.411: IPv6 NAT: icmp src (2000::1) -> (192.168.178.101), dst (2001::C0A8:B208) -> (192.168.178.8)

*Mar  1 00:06:59.427: IPv6 NAT: ipv6nat_find_entry_v4tov6:

     ref_count = 1,

                                usecount = 0, flags = 2, rt_flags = 0,

                                more_flags = 0

*Mar  1 00:06:59.463: IPv6 NAT: ipv6nat_find_entry_v4tov6:

     ref_count = 1,

                                usecount = 0, flags = 2, rt_flags = 0,

                                more_flags = 0

*Mar  1 00:06:59.463: IPv6 NAT: icmp src (2000::1) -> (192.168.178.101), dst (2001::C0A8:B208) -> (192.168.178.8)

*Mar  1 00:06:59.475: IPv6 NAT: ipv6nat_find_entry_v4tov6:

     ref_count = 1,

                                usecount = 0, flags = 2, rt_flags = 0,

                                more_flags = 0

*Mar  1 00:06:59.483: IPv6 NAT: ipv6nat_find_entry_v4tov6:

     ref_count = 1,

                                usecount = 0, flags = 2, rt_flags = 0,

                                more_flags = 0

*Mar  1 00:06:59.483: IPv6 NAT: icmp src (2000::1) -> (192.168.178.101), dst (2001::C0A8:B208) -> (192.168.178.8)

*Mar  1 00:06:59.491: IPv6 NAT: ipv6nat_find_entry_v4tov6:

     ref_count = 1,

                                usecount = 0, flags = 2, rt_flags = 0,

                                more_flags = 0

*Mar  1 00:06:59.507: IPv6 NAT: ipv6nat_find_entry_v4tov6:

     ref_count = 1,

                                usecount = 0, flags = 2, rt_flags = 0,

                                more_flags = 0

*Mar  1 00:06:59.507: IPv6 NAT: icmp src (2000::1) -> (192.168.178.101), dst (2001::C0A8:B208) -> (192.168.178.8)

*Mar  1 00:06:59.515: IPv6 NAT: ipv6nat_find_entry_v4tov6:

     ref_count = 1,

                                usecount = 0, flags = 2, rt_flags = 0,

                                more_flags = 0

Has anyone gotten this to work?  It'd be nice to have all the incoming IPv6 connections overloaded onto on IP address, and use v4-mapped to avoid lengthy batteries of destination entries and keep the router config short and simple.

Any info will help.

Thanks,

John

2 Replies 2

Laurent Aubert
Cisco Employee
Cisco Employee

Hi John,

It seems you are hitting CSCsh02715 but this bug has been closed due to lack of traction from the customer who found it.

I recommend you to try 15M/T based images to see if it's working otherwise you can open a TAC SR and referencing this bug but my guess is they will ask you first to try the latest version available anyway ;-)

HTH

Laurent.

That was it.  It works on 12.4 "T" trains and 15 "M" trains.

Thanks,

John

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