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I have a 11year old modem. However from my knowledge it isn't giving me problems.

I ran an ipv6 test I got "10/10" for for your IPv4 stability and readiness and 0/10 for IPv6. I then tried running it w/o my router wondering if that was a problem and i got 7/10, 0/10 to my surprise.

Anyways it says "Your DNS server (possibly run by your ISP) appears to have IPv6 Internet access" on both runs so i am wondering, is my modem the problem? I know my 'new' router (i think its a 4yr model but apparently solid) doesnt support it with current firmware and my ISP does support ipv6. I cant use ipv6 cause of my router and i might have to request ipv6 support from my ISP but before i do does modems affect it?

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What modem do you have? What IPv6 test did you ran? – Tom Wijsman Sep 25 '11 at 19:48
Modems, AFAIK, have a MAC address but no IP address. Therefore, it simply converts any data link-level data it receives. I'm probably wrong. – digitxp Sep 25 '11 at 19:49
@digitxp: Most "modems" these days are in fact routers with additional DSL or cable connectivity support, and perform many IP functions. My ISP-provided device has three IPv4 addresses (WAN, user LAN, mgmt LAN). – grawity Sep 25 '11 at 21:31

These days, most consumer "modems" are in fact routers with additional DSL or cable ports. At least in the case of ADSL, the "modem" performs such functions as obtaining an IPv4 address from my ISP through either DHCP or PPP(oE|oA), distributing addresses to my LAN, and finally publishing management functions over HTTP, Telnet and SNMP.

To use native (ISP-provided) IPv6, the router must obtain an IPv6 address for itself and correctly forward IPv6 packets between your LAN and the ISP. (I'm not entirely sure if ICMPv6 Router Advertisements are forwarded as well, or if the router is supposed to generate them itself – I'm guessing the latter.)

Note: I do not have an IPv6-capable 'modem' here. I'm very likely to be wrong.

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No, you are completely correct :) The router usually uses DHCPv6-Prefix-Delegation to get IPv6 addresses for itself and for all networks, and then generates Router Advertisements (RA's) to let all devices know about those address prefixes. – Sander Steffann Sep 25 '11 at 22:57

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