WB1 9.31 ISATAP Tunneling

9.31 ISATAP Tunneling

• Remove the 6to4 tunnels connecting R3, R4, and R5.
• Using their Loopback 0 IPv4 addresses connect  R3, R4, and R5 R1, SW1, and SW2 via
ISATAP tunnels.
• Use the /64 IPv6 prefix 2001:1:0:345::/64 to allocate IPv6 addresses to the
tunnel endpoints.
• Create additional IPv6 Loopback interfaces on all three routers with the
IPv6 addresses 2001:1:0:Y::Y/64, and use static routing to obtain full
connectivity.

------------------

R3:
no interface Tunnel345
!
interface Tunnel345
ipv6 address 2001:1:0:345::/64 eui-64
tunnel source Loopback0
tunnel mode ipv6ip isatap
!
interface Loopback100
ipv6 address 2001:1:0:3::3/64
!
ipv6 route 2001:1:0:4::/64 2001:1:0:345:0:5efe:9601:404
ipv6 route 2001:1:0:5::/64 2001:1:0:345:0:5efe:9601:505

R4:
no interface Tunnel345
!
interface Tunnel345
ipv6 address 2001:1:0:345::/64 eui-64
tunnel source Loopback0
tunnel mode ipv6ip isatap
!
interface Loopback100
ipv6 address 2001:1:0:4::4/64
!
ipv6 route 2001:1:0:3::/64 2001:1:0:345:0:5efe:9601:303
ipv6 route 2001:1:0:5::/64 2001:1:0:345:0:5efe:9601:505

R5:
no interface Tunnel345
!
interface Tunnel345
ipv6 address 2001:1:0:345::/64 eui-64
tunnel source Loopback0
tunnel mode ipv6ip isatap
!
interface Loopback100
ipv6 address 2001:1:0:5::5/64
!
ipv6 route 2001:1:0:4::/64 2001:1:0:345:0:5efe:9601:404
ipv6 route 2001:1:0:3::/64 2001:1:0:345:0:5efe:9601:303

--------------------

ISATAP (Intra-Site Automatic Tunnel Addressing Protocol) is a technology that
contrasts 6to4 automatic tunnels. While 6to4 automatically generates a /48 prefix
out of an IPv4 address, ISATAP uses the IPv4 domain as a “multi-access” media
with IPv4 addresses being the rough equivalent of Ethernet MAC addresses.

Specifically, ISATAP constructs the interface identifier (last 64 bits) of the IPv6
address based on the IPv4 address of a host using the EUI-64 rules. Thus, given
that you already have a /64 IPv6 prefix, you can allocate IPv6 addresses to
tunnel endpoints performing simple manipulations over the IPv4 endpoint
addresses. Specifically, the interface ID is constructed as follows:

EUI-64 = 0000 (16 bits) + 5EFE (16 bits) + IPv4 Address (32 bits).

Therefore, if you select the prefix 2001:1:0:345::/64, then R3 will have the IP
address:

2001:1:0:345:0:5efe:9601:0303/64

Where 9601 is for 150.1 and 0303 is for last two octets of the IP address. When
configuring an IOS router for ISATAP, you can automatically generate interface
ID’s with the eui-64 keyword.

Unlike the 6to4 tunnels, ISATAP tunnels cannot automatically extract the
destination. Therefore, you must use static routes that point to the exact IPv6
endpoint on the other end of the tunnel.

------------------------

Rack1R5#show interfaces tunnel 345
Rack1R5#show ipv6 interface tunnel 345
Rack1R5#ping 2001:1:0:345:0:5efe:9601:404
Rack1R5#ping 2001:1:0:345:0:5efe:9601:303
Rack1R5#ping 2001:1:0:4::4
Rack1R5#ping 2001:1:0:3::3