<br><br><div class="gmail_quote">On Mon, May 9, 2011 at 2:14 AM, Fred Baker <span dir="ltr"><<a href="mailto:fred@cisco.com">fred@cisco.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div class="im"><br>
On May 8, 2011, at 8:26 PM, Dave Taht wrote:<br>
<br>
> Is there a standard for renaming fe80:: addresses to represent they are interfacing with different vlans?<br>
<br>
</div>well, yes. Link-local addresses (FE80::/10) areas you say interpreted only in the LAN in question. The usual approach is to give the LAN a subnet prefix. The standard is RFC 4291.<br>
<br>
<a href="http://www.ietf.org/rfc/rfc4291.txt" target="_blank">http://www.ietf.org/rfc/rfc4291.txt</a><br>
</blockquote></div><br>So, there isn't a standard for using vlans and ipv6. <br><br>aformentioned RFC:<br><br><pre>2.5.1. Interface Identifiers<br><br> Interface identifiers in IPv6 unicast addresses are used to identify<br>
interfaces on a link. They are required to be unique within a subnet<br> prefix. It is recommended that the same interface identifier not be<br> assigned to different nodes on a link. They may also be unique over<br>
a broader scope. In some cases, an interface's identifier will be<br> derived directly from that interface's link-layer address. The same<br> interface identifier may be used on multiple interfaces on a single<br>
node, as long as they are attached to different subnets.<br></pre>"It is recomended that the same interface identifier not be assigned to different nodes on a link"<br><br>vs<br><br><pre>"The same interface identifier may be used on multiple interfaces on a single<br>
node, as long as they are attached to different subnets."</pre>
<br>Linux - or at least the defaults inside of openwrt - take the latter approach. This strikes me as error prone - and further does not discuss the effects of what a bridge should look like.<br><br>For error prone-ness - it is possible in my case, the vlans are not vlans! although their naming scheme (ethX.Y) suggests they are. And a typical user might plug two different lans together on one cable anyway. <br>
<br>Also:<br><br> Should the bridge itself have a unique link local over the underlying interfaces?<br><br>Given that we have a profusion of numbers available for link-local addresses, I can see no harm and much gain in *always* constructing a verify-ably unique fe80::XX:VLAN:EUI-64/64 prefix on a per-interface and per-virtual-interface basis on a given router. <br>
<br>ensuring unique FE80s from a given host would be enormously less confusing when looking at and comparing wireshark traces of the babel protocol, for example. ( <b><a href="http://tools.ietf.org/html/rfc6126">http://tools.ietf.org/html/rfc6126</a> )</b><br>
<br>What's not clear to me after reading RFC4291 twice this morning is that although a fe80:: is a /10, is if the bits above the interface id (as per the above "XX:VLAN:") truly are legit to be used, or a modified unique EUI-64 should be used.<br>
<br>A VLAN identifier is 12 bits in length, so the "V" portion of the above proposal could be dropped. (Not that I know how to extract the vlan identifier from the interface anyway) XX would be used to distinguish between interfaces that had no corresponding info but conflicted with addresses already on the router. <br>
<br>I realize this is somewhat off topic for the bloat list, but I was trying to get where I could actually test the IPv6 ECN patches I'd folded in across the routers(s) and running into trouble.<br><br>-- <br>Dave Täht<br>
SKYPE: davetaht<br>US Tel: 1-239-829-5608<br><a href="http://the-edge.blogspot.com" target="_blank">http://the-edge.blogspot.com</a> <br>