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Old 06-28-2014, 06:52 PM   #1
psycroptic
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necessary to set IPv6 global addresses on LAN & WAN router interfaces?


my ISP is Comcast, and they have enabled dual-stack v4/v6 for all of their customers. I have succesfully configured prefix delegation on my routers at various sites, and things seem to be working fine (or have been for the past ~6 months.) But i have noticed one thing: normally i have been configuring my routers to pull a /64 & split it for all the clients on the internal LANs. The router typically assigns an address from the /64 pool to its internal LAN interface, and leaves the external interface without a global address. I have read that routers do not necessarily need to have global addresses on all interfaces, as they use the link-local addresses to communicate with their default gateways & send traffic.

But many home routers & other configs of other Linux routers i've seen, seem to add global addresses to both the LAN and WAN interfaces. Is there a reason they do this? I know that even without a global address on the WAN side, I am still able to make connections to internet hosts/sites from my router; the source IP is the global address assigned to the internal interface.
 
Old 06-29-2014, 01:09 AM   #2
rhoekstra
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Ip6 doesn't use NAT. And your link local address is not routable. You will need a global address to access the internet on your end device..
 
Old 06-29-2014, 02:04 AM   #3
psycroptic
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Quote:
Originally Posted by rhoekstra View Post
You will need a global address to access the internet on your end device..
right, i have exactly 1 global address, assigned to the internal interface of my router. it's numbering is a part of the /64 i am receiving from my ISP... this is enough for the router to be able to access the internet. the external interface does not have a global address....

and if, for example, i ping another IPv6 internet host from my router, packet dumps on that host show the source IP to be that same address assigned to the router's internal interface

Last edited by psycroptic; 06-29-2014 at 02:06 AM.
 
Old 07-03-2014, 05:35 AM   #4
rhoekstra
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Your ISP shall have an IPv6 address configured, as will your router have one, to communicate between each other. The address on the external (ISP side) interface of your router should not be part of the /64 you have gotten from your ISP.
the /64 is for your own use, within your own network..

Code:
ISP gateway, ends on ::1 (for example 2001:beef:1234:5678::1, ISP network range)

|

your router external interface, ends on ::2 (for example 2001:beef:1234:5678::2 ISP network range)

|router|

your router internal interface, ends on ::1 (within your /64 range, like 2001:beef:8765:4321::1) 

|

internal devices, all within /64 range, like 2001:beef:8765:4321::2 et cetera)
Above trying to illustrate how it should be set up.. hopefully you can relate it to your situation and work out how your router can act as an IPv6 router to your internal network..
 
  


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