IPv6 ISATAP configuration example with a Cisco router as a client
This example demonstrates ISATAP configuration on the head-end router and a simulated ISATAP client using a Cisco router. Usually the client is a Windows PC with IPv6 enabled, initiating the tunnel. For testing and verification purposes, a Cisco router closest to the clients can act as a client. Check feature navigator to verify head-end router image supports ISATAP tunnels. Check feature navigator to verify simulated client router supports manually configured IPv6 over IPv4 tunnels.
Head-end router configuration
ipv6 unicast-routing ! interface Loopback0 ip address 184.108.40.206 255.255.255.255 ! interface Tunnel1 no ip address no ip redirects ipv6 address 2001:DB8:CAFE:65::/64 eui-64 <<<Any /64 IPv6 address will work no ipv6 nd ra suppress <<< IPv6 ra is suppressed by default on tunnel. Need to re-enable for client auto-configuration. tunnel source Loopback0 tunnel mode ipv6ip isatap
Simulated ISATAP client on Cisco router
interface ethernet0 ip address 220.127.116.11 255.255.255.0 ! interface Tunnel1 no ip address ipv6 address autoconfig ipv6 enable tunnel mode ipv6ip tunnel source ethernet0 tunnel destination 18.104.22.168
Related show Commands
This section provides information you can use to confirm your configuration is working properly.
Certain show commands are supported by the Output Interpreter Tool (registered customers only), which allows you to view an analysis of show command output.
Client Tunnel1 should acquire IPv6 address prefix from head-end. Then it appends client source IPv4 address to then end. In this exampls, 22.214.171.124 => 0F00:0001
show ipv6 interface tunnel1 Tunnel1 is up, line protocol is up IPv6 is enabled, link-local address is FE80::F02:880 No Virtual link-local address(es): Stateless address autoconfig enabled Global unicast address(es): 2001:DB8:CAFE:65::F00:0001, subnet is 2001:DB8:CAFE:65::/64 [EUI/CAL/PRE] valid lifetime 2591979 preferred lifetime 604779 Joined group address(es): FF02::1 FF02::1:FF02:880 MTU is 1480 bytes ICMP error messages limited to one every 100 milliseconds ICMP redirects are enabled ICMP unreachables are sent ND DAD is enabled, number of DAD attempts: 1 ND reachable time is 30000 milliseconds (using 30000) Default router is FE80::5EFE:F64:801 on Tunnel1
IPv6 Router advertisement information can be seen from,
show ipv6 router Router FE80::5EFE:F64:801 on Tunnel1, last update 21 min Hops 64, Lifetime 1800 sec, AddrFlag=0, OtherFlag=0, MTU=1480 HomeAgentFlag=0, Preference=Medium Reachable time 0 (unspecified), Retransmit time 0 (unspecified) Prefix 2001:DB8:CAFE:65::/64 onlink autoconfig Valid lifetime 2592000, preferred lifetime 604800
If IPv6 unicast-routing is disabled on the client router, it will also install a default static route pointing towards the ISATAP head-end router.
show ipv6 route
IPv6 Routing Table - default - 4 entries Codes: C - Connected, L - Local, S - Static, U - Per-user Static route B - BGP, R - RIP, I1 - ISIS L1, I2 - ISIS L2 IA - ISIS interarea, IS - ISIS summary, D - EIGRP, EX - EIGRP external ND - Neighbor Discovery, l - LISP 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 [2/0] via FE80::5EFE:F64:801, Tunnel1 C 2001:DB8:CAFE:65::/64 [0/0] via Tunnel1, directly connected L 2001:DB8:CAFE:65::F02:880/128 [0/0] via Tunnel1, receive L FF00::/8 [0/0] via Null0, receive