The world of 6RD / Configuring 6RD in Cisco IOS

Well, early in this month I went to Cisco Configuration guide to refresh my concept, and interesting enough that I've found this new topic under IPv6 Tunneling. I used to look at 12.4T IOS configuration guide, based on my CCIE lab study habit, until I realized that Cisco always developed their IOS, and now its been 15.2S train >.<.

ok let's go back to the 6RD concept, I will brief out a scenario, then go to an overview of this technology and, finally, followed by the Configuration required to run 6RD:

Scenario

1. R1 will act as Border Router (BR) with Prefix [2012:0123::/32], connecting to IPv4 island 192.168.x.x/16 using EIGRP 123 and also connecting to IPv6 Island [2001:1212:2928::/64] using EIGRPv6.
2. R2 will act as Customer Edge Router (CE), connecting to IPv4 island 192.168.x.x/16 using EIGRP 123 and also connecting to IPv6 Island [2012:0123:202:2727::/64], which is derived from 6RD using RIPng
3. R3 will act as Customer Edge Router (CE), connecting to IPv4 island 192.168.x.x/16 using EIGRP 123 and also connecting to IPv6 Island [2012:0123:303:3434::/64], which is derived from 6RD using OSPFv3
4. Make Sure both SW2 and R4 can reach 2001:1212:2928::/64 subnet :)

6RD Overview

6RD (Rapid Deployment), in my oppinion,  is a descendant of 6to4 Tunneling. 6to4 tunneling is cool, but think about this, when a SP wanna deploy a large scale deployment of 6to4, they cannot use their own IPv6 prefix, because 2002::/16 is mandatory in 6to4 Deployment.

Well, 6RD is then born to overcome the 6to4 tunneling with give the freedom to the SP to use their own IPv6 prefix. How the 6RD work, in the example above, the SP will have the prefix 150.1.x.x/16 as their IP Public.

SP will assign their own IPv6 Prefix, in this case is : 2012:0123::/32 as their prefix. Well because 150.1.x.x is well known in this SP, they can eventually ‘SUMMARIZE’ or tell the router that the first 16-bit prefix are well know, so they will not converted into the IPv6 Prefix. In this case R1-R3 will have their 6RD prefix:

R1 : 150.1.1.1 ==> OMIT bit.OMIT bit. 00000001. 00000001 ==> 0101 ==> [2012:0123:0101::/48]
R2 : 150.1.2.2 ==> OMIT bit.OMIT bit. 00000010. 00000010 ==> 0202 ==> [2012:0123:0202::/48]
R3 : 150.1.3.3 ==> OMIT bit.OMIT bit. 00000011. 00000011 ==> 0303 ==> [2012:0123:0101::/48]

R2 can use additional subnet to identify that this subnet is sourcing from the R2, here is the idea
2012:123:202::/48 (R2 Tunnel to R1) ==> 2012:123:202:2727::/64 (R2’s own prefix)

While R3 can use additional subnet to identify that this subnet is sourcing from the R3, here is the idea
2012:123:303::/48 (R2 Tunnel to R1) ==> 2012:123:303:3434::/64 (R3’s own prefix)

In this case, if R1,R2,R3 want to communicate each other, they will use 2012:123::/32 prefix, while CE (R2-R3) will have a default-route to the BR (R1) if they want to go outside 2012:123::/32 prefix.

In the production CE device could be a Wi-Fi router, such as Linksys, that will have their inside interface having native IPv6 Prefix to the end user like Windows 7. In our example those client are SW2 and R4. The goal is that those hosts can communicate with each other  as well as connecting to the Internet using pure IPv6 prefix [2001:1212:2928::/64], how cool is that.

R2 Configuration

R2 (CE)
!
ipv6 general-prefix PREFIX 6rd Tunnel123
ipv6 unicast-routing
ipv6 cef
!
interface Tunnel123
 no ip address
 no ip redirects
 ipv6 enable
 tunnel source Loopback0
 tunnel mode ipv6ip 6rd
 tunnel 6rd ipv4 prefix-len 16
 tunnel 6rd prefix 2012:123::/32
 tunnel 6rd br 150.1.1.1
!
ipv6 route 2012:123::/32 Tunnel123
ipv6 route ::/0 Tunnel123 2012:123:101::
!
interface FastEthernet0/1
 no ip address
 duplex full
 speed 100
 ipv6 address 2012:123:202:2727::2/64
 ipv6 rip RIP6 enable
!
ipv6 router eigrp 12
!
End


R3 Configuration

R3 (CE)
!
ipv6 general-prefix PREFIX 6rd Tunnel123 (Not Mandatory)
ipv6 unicast-routing
ipv6 cef
!
interface Tunnel123
 no ip address
 no ip redirects
 ipv6 enable
 tunnel source Loopback0
 tunnel mode ipv6ip 6rd
 tunnel 6rd ipv4 prefix-len 16
 tunnel 6rd prefix 2012:123::/32
 tunnel 6rd br 150.1.1.1
!
ipv6 route 2012:123::/32 Tunnel123
ipv6 route ::/0 Tunnel123 2012:123:101::
!
!
interface Serial1/2
 description Connecting to R4 using Pure IPv6 prefix
 no ip address
 encapsulation ppp
 no peer neighbor-route
 ipv6 address 2012:123:303:3434::3/64
 ipv6 ospf 34 area 0
 serial restart-delay 0
!
ipv6 router ospf 34
 default-information originate metric 333
 redistribute static metric-type 1
!
end

R1 Configuration

R1 – BR
!
ipv6 general-prefix PREFIX 6rd Tunnel123
ipv6 unicast-routing
ipv6 cef
!
interface Tunnel123
 no ip address
 no ip redirects
 ipv6 enable
 ipv6 eigrp 12
 tunnel source Loopback0
 tunnel mode ipv6ip 6rd
 tunnel 6rd ipv4 prefix-len 16
 tunnel 6rd prefix 2012:123::/32
!
ipv6 route 2012:123::/32 Tunnel123
!
!
interface Serial1/1
 description Connecting to R2 VRF using Pure IPv6 prefix
 no ip address
 encapsulation ppp
 no peer neighbor-route
 ipv6 address 2001:1212:2928::1/64
 ipv6 eigrp 12
 serial restart-delay 0
!
ipv6 router eigrp 12
 no shutdown
!
end


Verification

R2#show tunnel 6rd
Interface Tunnel123:
  Tunnel Source: 150.1.2.2
  6RD: Operational, V6 Prefix: 2012:123::/32
       V4 Prefix, Length: 16, Value: 150.1.0.0
       V4 Suffix, Length: 0, Value: 0.0.0.0
       Border Relay address: 150.1.1.1
  General Prefix: 2012:123:202::/48
R2#
R2#show ipv6 interface tunnel 123
Tunnel123 is up, line protocol is up
  IPv6 is enabled, link-local address is FE80::9601:202
  No Virtual link-local address(es):
  No global unicast address is configured
  Joined group address(es):
    FF02::1
    FF02::2
    FF02::1:FF01:202
  MTU is 1480 bytes
  ICMP error messages limited to one every 100 milliseconds
  ICMP redirects are enabled
  ICMP unreachables are sent
  Post_Encap features: Tunnel 6RD
  ND DAD is not supported
  ND reachable time is 30000 milliseconds (using 30000)
  ND RAs are suppressed (periodic)
  Hosts use stateless autoconfig for addresses.

R3#show tunnel 6rd
Interface Tunnel123:
  Tunnel Source: 150.1.3.3
  6RD: Operational, V6 Prefix: 2012:123::/32
       V4 Prefix, Length: 16, Value: 150.1.0.0
       V4 Suffix, Length: 0, Value: 0.0.0.0
       Border Relay address: 150.1.1.1
  General Prefix: 2012:123:303::/48
R3#
R3#show ipv6 int
R3#show ipv6 interface tun
R3#show ipv6 interface tunnel 123
Tunnel123 is up, line protocol is up
  IPv6 is enabled, link-local address is FE80::9601:303
  No Virtual link-local address(es):
  No global unicast address is configured
  Joined group address(es):
    FF02::1
    FF02::2
    FF02::5
    FF02::1:FF01:303
  MTU is 1480 bytes
  ICMP error messages limited to one every 100 milliseconds
  ICMP redirects are enabled
  ICMP unreachables are sent
  Post_Encap features: Tunnel 6RD
  ND DAD is not supported
  ND reachable time is 30000 milliseconds (using 30000)
  ND RAs are suppressed (periodic)
  Hosts use stateless autoconfig for addresses.

R1#show tunnel 6rd
Interface Tunnel123:
  Tunnel Source: 150.1.1.1
  6RD: Operational, V6 Prefix: 2012:123::/32
       V4 Prefix, Length: 16, Value: 150.1.0.0
       V4 Suffix, Length: 0, Value: 0.0.0.0
  General Prefix: 2012:123:101::/48
R1#
R1#show ipv6 interface tunnel 123
Tunnel123 is up, line protocol is up
  IPv6 is enabled, link-local address is FE80::9601:101
  No Virtual link-local address(es):
  No global unicast address is configured
  Joined group address(es):
    FF02::1
    FF02::2
    FF02::A
    FF02::1:FF01:101
  MTU is 1480 bytes
  ICMP error messages limited to one every 100 milliseconds
  ICMP redirects are enabled
  ICMP unreachables are sent
  Post_Encap features: Tunnel 6RD
  ND DAD is not supported
  ND reachable time is 30000 milliseconds (using 30000)
  ND RAs are suppressed (periodic)
  Hosts use stateless autoconfig for addresses.


Conectivity Testing

SW2#ping 2001:1212:2928::1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:1212:2928::1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 48/68/96 ms
SW2#traceroute 2001:1212:2928::1

Type escape sequence to abort.
Tracing the route to 2001:1212:2928::1

  1 2012:123:202:2727::2 52 msec 28 msec 4 msec
  2 2001:1212:2928::1 64 msec 108 msec 48 msec


R4#ping 2001:1212:2928::1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:1212:2928::1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 92/108/120 ms
R4#trace 2001:1212:2928::1
Type escape sequence to abort.
Tracing the route to 2001:1212:2928::1

  1 2012:123:303:3434::3 52 msec 40 msec 32 msec
  2 2001:1212:2928::1 116 msec 112 msec 112 msec


Indeed a great and cool feature there. I hope that have been informative, and you can get the big picture of the 6RD techhnology