Fred/all See
http://www.bufferbloat.net/issues/126 which has a ip -6 addr and ifconfig dump and see if that "seems right" to you. On Mon, May 9, 2011 at 9:57 AM, Fred Baker <f...@cisco.com> wrote: > > On May 9, 2011, at 7:59 AM, Dave Taht wrote: > > On Mon, May 9, 2011 at 2:14 AM, Fred Baker <f...@cisco.com> wrote: > > > > On May 8, 2011, at 8:26 PM, Dave Taht wrote: > >> > Is there a standard for renaming fe80:: addresses to represent they > are interfacing with different vlans? > >> > >> 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. > >> > >> http://www.ietf.org/rfc/rfc4291.txt > >> > > So, there isn't a standard for using vlans and ipv6. > > There is one for IPv6. How you use it in your addressing plan is your call. > You could map subnet numbers to vlan numbers of that made sense for you, but > I'd be surprised if folks generally wanted to do that; believe it or not, > not all networks are built around vlans. Many are built around MPLS, and > many use neither - they simply use IP subnets. > > > aformentioned RFC: > > > > 2.5.1. Interface Identifiers > > > > Interface identifiers in IPv6 unicast addresses are used to identify > > interfaces on a link. They are required to be unique within a subnet > > prefix. It is recommended that the same interface identifier not be > > assigned to different nodes on a link. They may also be unique over > > a broader scope. In some cases, an interface's identifier will be > > derived directly from that interface's link-layer address. The same > > interface identifier may be used on multiple interfaces on a single > > node, as long as they are attached to different subnets. > > > > "It is recomended that the same interface identifier not be assigned to > different nodes on a link" > > There is a stronger statement than the one in 2.5.1; the text above says > that "They are required to be unique within a subnet prefix." > > > vs > > > > "The same interface identifier may be used on multiple interfaces on a > single > > node, as long as they are attached to different subnets." > > > > > > 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. > > > > 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. > > So you're concerned that two interfaces might have the same interface > identifier but different supporting MAC addresses within the same subnet? > Yes, in this model that is possible. I personally would suggest that one > uses duplicate address detection to detect and avoid the situation. Does > Linux do that? From a requirements perspective, "may" is a lot weaker than > "required". > > > Also: > > > > Should the bridge itself have a unique link local over the underlying > interfaces? > > I'm not sure what "bridge" you're talking about. If by "bridge" you're > referring to a linux system using the same IID on multiple interfaces, IIDs > "are required to be unique within a subnet prefix" per the text you quoted > above. > > > 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. > > That's certainly your choice; it doesn't map to any address format in the > spec; 2.5.6 very specifically sets those bits to zero in a link-local > address (I would argue it should therefore specify the prefix as FE80::/64, > not FE80::/10). How do the hosts know what VLAN they are on? That's > generally either information known by the switch and used on trunk ports, or > configured data. The host generally has no idea what VLAN it's on. Recall > that link-local addresses are what the device develops before it has any > knowledge of the world around it. > > > 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. ( http://tools.ietf.org/html/rfc6126 ) > > > > 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. > > What you're describing is essentially a site-local address, although the > format uses FEC0::/10. Did you read the part about site-local addresses > (2.5.7)? > > | 10 | > | bits | 54 bits | 64 bits | > +----------+-------------------------+----------------------------+ > |1111111011| subnet ID | interface ID | > +----------+-------------------------+----------------------------+ > > You have tried to specify the "Subnet ID" and use it as a link-local. > > I'll suggest you read: > > http://www.ietf.org/rfc/rfc3879.txt > 3879 Deprecating Site Local Addresses. C. Huitema, B. Carpenter. > September 2004. (Format: TXT=24142 bytes) (Status: PROPOSED STANDARD) > and > http://www.ietf.org/rfc/rfc4193.txt > 4193 Unique Local IPv6 Unicast Addresses. R. Hinden, B. Haberman. > October 2005. (Format: TXT=35908 bytes) (Status: PROPOSED STANDARD) > > > 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. > > > > 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. > > I actually think you would do well to join > https://www.ietf.org/mailman/listinfo/ipv6 and discuss it on i...@ietf.org > . > > -- Dave Täht SKYPE: davetaht US Tel: 1-239-829-5608 http://the-edge.blogspot.com
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