> There are essentially two ways to break loops: either by using a > "routing protocol" of some kind that imposes a correct routing structure > on the set of proxies; or by using a form of "loop detection" option in > the ND messages. The spanning tree algorithm is an example of the first > class of solution; we could also conceivably use RIP or OSPF with host > entries.
And RBridges argues that one can do this without any changes on hosts or routers; they see the same behavior as without the RBridges even though the RBridges use a routing protocol (on L2 and/or L3 addresses) between eachother. > I looked at the second class of solutions in a now expired draft. The > basic idea is to add a "forwarded by" option in the discovery messages > sent by the proxy, and to use that option to detect loops, either with a > hop limit (don't forward more that N times) or with a packet inspection > (don't forward what you have already forwarded once). If one were do to a loop detection scheme something like that would make sense. > The routing or spanning tree solution is the most transparent to the > hosts, since it does not change any byte in the ND packets. However, > transparency may not be entirely desired, since SEND requires being > fairly explicit about relays. The "forwarded by" option is perhaps more > powerful, as it allows for real-time discovery of alternate paths. I guess I don't understand the need for explicit relays. SEND works over existing L2 bridges - it can't even see that they are there. (As a result there are L2 derived security issues - you can "redirect" things at L2 unless L2 is somehow secure.) I guess I don't understand the tradeoffs between running SEND over a larger transparently "bridged" LAN vs. using "relays" that are visible to SEND. Erik -------------------------------------------------------------------- IETF IPv6 working group mailing list [EMAIL PROTECTED] Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
