E4200 - IPv6 Neighbor Discovery [ Edited ]

[simon.labbe]

Hi,

I am currently developping an embedded IPv6 stack and I needed to get an IPv6 compatible router to perform different tests. I purchased an E4200 router, knowing that the latest firmware includes Native IPv6 support. On Cisco blog, I read that the router should now support RFC6204:

"While many of the base IPv6 specifications have been available for years, the IETF published RFC 6204 which defines the basic requirements for an IPv6 home router as recently as April 2011. IP is one of the most important protocols to the Internet, and IPv6 is the biggest change in IP in over 30 years. We want to be careful that the implementations we ship work well and adhere to the latest standards so that we do not hinder the adoption of IPv6 by content providers and ISPs."

Source: http://blogs.cisco.com/consumer/linksys-e4200-wireless-router-supports-ipv6/

My first test step involved the Neighbor Discovery Protocol and RFC6204 clearly states the following:

"The IPv6 CE router MUST support router behavior according Neighbor Discovery for IPv6 [RFC4861]"

My first question is the following: Is it normal that I  don't see any 'Router Advertisement' messages send by the router? According to RFC4861, it is not.

It must day that my ISP doesn't support IPv6 so it doesn't assign a global IPv6 address to my router. However, I only require to have a link-local IPv6 link (at least for now). Can it explain why the router doesn't send periodic "Router Advertisement" messages?

Second, the router correcty responds to my "Neighbor Solicitation" messages when I try to ping the link-local address. But

it is not responding to my "Router Solicitation" messages. It's also conflicting with RFC4861.

Does someone know what is going on with Neighbor Discovery on that router? I will appreciate any comments & replies.

Many thanks!

[gv]

The router most likely won't send RAs unless it has a working IPv6 Internet connection.

If it would send out RAs, clients would pick it up and use it. Systems like windows7 which prefer IPv6 to IPv4 for connections will then be severly slowed down when connecting to dual-stacked destinations as they will always first try IPv6 and then after a timeout of 60 (?) seconds revert to IPv4.

Thus for a consumer device like the E4200 it seems more then reasonable not to send out RAs unless the router has a working IPv6 connection.

For a link-local IPv6 link inside your LAN you don't need a router nor RAs from a router. Link-local connections are not routed.

[simon.labbe]

Many thanks for you input. We decided to return the consumer router and we purchased a CISCO 881. The IOS software is much more flexible and it actually do what we want.

IPv6 experts are not easy to find so if you don't mind, I would have another question on a behavior I observed recently with our CISCO 881 router.

I implemented the ICMPv6 echo request functionnality and it works fine when I try to reach different hosts on my network.

However,  I also tested it by using the link-local IP address of my router as the target. First, my stack sends a Neighbor Solicitation message (using IPv6-MCAST dest MAC address) to resolve the router IP address (assuming it is not yet on the router list) . The router reply back with a Neighbor Advertisement message, but does not includes the 'Target link-layer address' option into its message.

However, according the the RFC4861 (page 25),  in Neighbor Advertisement messages, the Target link-layer address "option MUST be included on link layers that have addresses when responding to multicast solicitations."

It looks like a bad implementation; I was expecting the Neighbor Advertisement message, even if sent by a router, to include the Target link-layer option when responding to my multicast Neighbor Solicitation. Do you agree with that?

Simon

[DMartocci]

Well that's a disappointment because alot of us still want to know the answers instead of hearing about you guys giving up and running away from the problem.

[gv]

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@DMartocci wrote:

Well that's a disappointment because alot of us still want to know the answers instead of hearing about you guys giving up and running away from the problem.

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Who is running away?

[lelguea]

i have ipv6 working. In diagnostic i can ping ipv6 only urls, for example www6.up.edu.mx and in state i see the global ipv6 address. (dont have a ipv6 dns server) but i can use ipv6 in the device connet to e4200.  i receive RA, but no Prefix information. how i confugure the segment of ipv6?  excuse my english, and greetings from Mexico City.

[marknotmarc]

I can not get IPv6 Neighbor Discovery to work either. I have native IPv6 through my ISP and it works when I connect directly to the modem and enable PPoE connection directly. When I establish a PPoE connection with the router it fails to retrieve my static IPv6 IP from the ISP. Here are my results:

http://eccleston.ca/Problems/e4200ipv6.html

[ScarletJamie]

@marknotmarc, I think this product by design will only support IPv6 on automatic mode and will not work if we will subscribe static IPv6 from ISP.

[marknotmarc]

I see that there is no option in the setup for manual entry. My points are:

1. Windows obtains the addresses automatically as the static IP is tied to my logon PPoE credentials, so why does the router not obtain the address.

2. As automatic does not seem to work, why is there not a manual option as there is in the ASUS RT-N66U or DD-WRT.

3. Linksys/Cisco state that it will support IPv6 and future proof your network directly on the box.

This fix is not a configration issue, but rather needs an addition to the firmware and yet everytime you contact Cisco you get questions such as, "How many wireless devices do you connect to the device?"