Am Dienstag 01 September 2009 17:34:44 schrieb Justin Dean: > At this point not all link sets have symmetric entries but hopefully this > helped illustrate how NHDP would handle this situation. IMO only the last > step is "wrong" otherwise links are kept on a per interface basis even with > multiple interfaces using the same IP address. The issue is with having > two different routers with the same address. One solution would be to > require that only unique addresses are included in hello messages. This > would remove the possibility of NHDP being used to advertize anycast > addresses. Another method would be to tag non-unique addresses > (LOCAL_IF:NON-UNIQUE) and store them apart from the other addresses in the > neighbor tuple. Maybe I have an suggestion how we can add the "same IP multiple times on different interfaces" without any overhead for normal operation in the messages. new TLV (both message TLV and address block TLV): IF_INDEX including a value of 1 bytes. The value must be 1 or higher. (this supports up to 255 interfaces with the same IP, which should be more than enough) --------- Every Node having the same IP multiple times add an IF_INDEX TLV as a message TLV to HELLOS with with the duplicate IPs as interface IP. instead of working with "neighbor_interface_ip", NHDP will always use a pair of "neighbor_interface_ip" and "neighbor_interface_index". This will guarantee that the pair is unique. If no IF_INDEX is attached to an interface IP, it's considered 0. All neighbor_interface IPs put into an HELLO will contain an IF_INDEX TLV, unless the stored index is 0. --------- If we would run NHDP this way with no duplicate IPs, there will be no change in the message structure at all. All interfaces will add "0" as the default if_index to their identification pair, but this don't need to be transmitted to neighbors. What do you think about it ? Henning Rogge
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