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Can I get neighbor information on ISATAP tunnel?

I configured ISATAP between two routers.

[Server cisco3845 ver 15.1(4)M12a]

interface Tunnel4
 no ip address
 no ip redirects
 ipv6 address 2001:22:33::/64 eui-64
 ipv6 enable
 ipv6 nd cache expire 10
 no ipv6 nd ra suppress
 tunnel source Loopback0
 tunnel mode ipv6ip isatap

[Client C891F ver=15.7(3)M4a]

interface Tunnel1
 no ip address
 ipv6 address autoconfig
 ipv6 enable
 tunnel source GigabitEthernet8
 tunnel mode ipv6ip
 tunnel destination


I could get neighbor information by "show ipv6 neighbors" as below on Cisco3845 as below,

IPv6 Address                              Age Link-layer Addr State Interface
2001:22:33::C0A8:806F                       0  REACH Tu4

But the result of same command on C891F was empty.


I seems older IOS tends to show the neighbor information on tunnel interface but newer IOS does not.

Is this difference made by cisco intentionally?

Is there any command to see Link-layer Address (IPv4 address in case of ISATAP) of neighbor on C891F ?


Best Regards,


VIP Advocate

Re: Can I get neighbor information on ISATAP tunnel?


Have you enabled it?

ipv6 unicast-routing

and share some output from both routers.

show ipv6 interface Tunnel 4


Deepak Kumar,
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Re: Can I get neighbor information on ISATAP tunnel?

yes, "ipv6 unicast-routing" is configured on ISATAP server router.

Output of "show ipv6 neighbors" on ISATAP server router(15.1(4)M12a) is as below,


P1-3845#sh ipv6 neighbors tunnel 4
IPv6 Address Age Link-layer Addr State Interface
2001:22:33::C0A8:806F 0 REACH Tu4


but there is no output by "show ipv6 neighbors" on ISATAP client router(15.7(3)M4a).

Cisco Employee

Re: Can I get neighbor information on ISATAP tunnel?

I think the issue is due more to the fact that you are using IOS is host mode (no ipv6 unicast-routing) than the IOS version itself.



Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
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Cuauhtémoc, Juárez
Ciudad de México, 06600

Re: Can I get neighbor information on ISATAP tunnel?

Hello Harold,


Thank you for suggestion.


I have already tried "ipv6 unicast-routing" on ISATAP client router, but the result was same.

"show ipv6 neighbors" was empty.


I also added " ipv6 nd autoconfig default-route" on tunnel interface of client router, and default route was added, but neighbor was not shown.

Best Regards,

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