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Is the use of link-local address required for IPv6 static routing next hop?

computerone1
Level 1
Level 1

The RFC for Neighbor Discovery (RFC4861), in section 8 states:

"A router MUST be able to determine the link-local address for each of
   its neighboring routers in order to ensure that the target address in
   a Redirect message identifies the neighbor router by its link-local
   address.  For static routing, this requirement implies that the next-
   hop router's address should be specified using the link-local address
   of the router.  For dynamic routing, this requirement implies that
   all IPv6 routing protocols must somehow exchange the link-local
   addresses of neighboring routers."

 

Yet, all documentation I encountered, including Cisco and Juniper, always use a Global Unicast Address or a Local Unicast Address as next hop for IPv6 static routing.

 

. is the use of link-local address mandatory as IPv6 static routing next hop?
. is the use of link-local address a best practice as IPv6 static routing next hop?

 

Thanks for any clarification :-)

 

1 Reply 1

Harold Ritter
Cisco Employee
Cisco Employee

You can use either a global or link local address as the next hop for a static route. If you use a link local address, you will need to also configure the interface, as the same link local address might  exist on several interface.

 

I would also recommend to explicitly configure the link local address if you use it as the next hop for your static route. This way you will not run in any issue if you change the hardware, which will change the MAC address, which will change the link local address, as the link local address is generated via EUI-64 by default.    

 

Regards,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
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