EIGRP IPv6 Link-Local Only Routing

[LeonardW]

Hey guys,

I have a question in regard to link local only routing like described in RFC7404.
In my Setup I use VLAN Interfaces for End-Host Networks which just have a link-local address and advertise the GUA Prefix via RAs with just the "on-link" flag set.

interface Vlan1000
ipv6 address FE80::1000:A link-local
 ipv6 nd prefix 2001:db8:cafe:1000::/64 infinite infinite no-autoconfig

So in the routing-table we just have a connected route, not a local route because there is no "real" IPv6 address on the SVI configured.

C   2001:db8:cafe:1000::/64 [0/0]
     via Vlan1000, directly connected

The point is, that I wanna advertise these connected routes through EIGRP, but it doesn't work.

router eigrp LAB
 !
 address-family ipv6 unicast autonomous-system ASN
  !
  af-interface default
   authentication mode md5
   authentication key-chain EIGRP
   passive-interface
  exit-af-interface
  !
  af-interface FastEthernet1/0/47
   summary-address 2001:db8:cafe:1000::/52
   no passive-interface
  exit-af-interface
  !
  topology base
   redistribute connected
  exit-af-topology
  eigrp stub connected summary
 exit-address-family
!

It starts working since I configure a ULA or GUA address on the interface (and I get a Local Receive Route in the RIB).

C   2001:db8:cafe:1000::/64 [0/0] 
     via Vlan1000, directly connected
L   2001:db8:cafe:1000::/128 [0/0]
     via Vlan1000, receive

Also the "redistribute connected" command doesn't help.

Is there any option to advertise these routes without configuring real addresses on the interfaces?

Thank you for your help and if there are some more information necessary I will share them here. :)

[Harold Ritter]

Hi Leonard,

> That's the point, the "C" route is created as soon as this "ipv6 nd" command is configured.
> In my eyes it doesn't makes sense to configure then a additional "ipv6 address" under the interface to get a "L" Route.

Configuring the "ipv6 address" is the proper way to do it. Anything else would be just a hack and wouldn't serve you well if anything breaks.

> Yeah, it's not a big deal, but still additional config and also a additional entry in the RIB, so if we could waive this, the config > and the RIB could be more "nice".

The entry in the RIB needs to be there if you need to route to the subnet anyhow. So not sure what you mean by additional entry in the RIB.

Regards,

[LeonardW]

>Configuring the "ipv6 address" is the proper way to do it. Anything else would be just a hack and wouldn't serve you well if anything >breaks.

Okay. :)

>The entry in the RIB needs to be there if you need to route to the subnet anyhow. So not sure what you mean by additional entry in >the RIB.
But that's exactly the point where I'm wondering.
In my Lab it had worked with static routing and without the "L" Route.

It's not possible to advertise through a routing protocol, but with static routing I can force the packets to go the "right" way and the it works. Also without a real address and just the "ipv6 nd prefix" command.