Hi we have a problem on using LKSCTP to form a 4 ways multi-homing network. Configuration - Node-A has 2 IP addresses in different subnets, known as IP-A (eth1), IP-B (eth2) - Node-B has 2 IP addresses in different subnets, known as IP-X (eth1), IP-Y (eth2) the four way paths are shown below. 1. IP-A (11.1.1.1) to IP-X (11.1.1.11) 2. IP-B (12.1.1.1) to IP-Y (12.1.1.11) 3. IP-A (11.1.1.1) to IP-Y (12.1.1.11) 4. IP-B (12.1.1.1) to IP-X (11.1.1.11) the HB/HB_ACK is normal for the paths " IP-A to IP-X" and "IP-B to IP-Y", but it is not correct for the rest of two. First of all, we are using iproute2 to form 2 table such that when IP-B arrives on IP-X, it will know how to route back to IP-B on the same interface, i.e (eth1). Same logic for the path "IP-A to IP-X". What we observed here is that when 12.1.1.1 sends INIT to 11.1.1.11, LKSCTP will send back the INIT_ACK to 12.1.1.1 using 12.1.1.11 but not using the IP 11.1.1.11. The above operation makes the subsequence HB/HB_ACK in using wrong IP address. TCP trace on eth1 18:02:41.058640 IP 12.1.1.1.2905 > 11.1.1.11.2905: sctp (1) [INIT] [init tag: 19933036] [rwnd: 102400] [OS: 16] [MIS: 16] [init TSN: 0] 18:02:41.061634 IP 12.1.1.1.2905 > 11.1.1.11.2905: sctp (1) [COOKIE ECHO] 18:02:41.062642 IP 12.1.1.1.2905 > 11.1.1.11.2905: sctp (1) [HB REQ] 18:02:41.062846 IP 11.1.1.11.2905 > 11.1.1.1.2905: sctp (1) [HB ACK] 18:02:41.361811 IP 11.1.1.11.2905 > 11.1.1.1.2905: sctp (1) [HB ACK] 18:02:41.661791 IP 11.1.1.11.2905 > 11.1.1.1.2905: sctp (1) [HB ACK] 18:02:41.961791 IP 11.1.1.11.2905 > 11.1.1.1.2905: sctp (1) [HB ACK] TCP trace on eth2 18:02:41.058755 IP 12.1.1.11.2905 > 12.1.1.1.2905: sctp (1) [INIT ACK] [init tag: 424726157] [rwnd: 131072] [OS: 5] [MIS: 5] [init TSN: 3340756356] 18:02:41.061696 IP 12.1.1.11.2905 > 12.1.1.1.2905: sctp (1) [COOKIE ACK] 18:02:41.062663 IP 12.1.1.11.2905 > 12.1.1.1.2905: sctp (1) [HB ACK] 18:02:41.062791 IP 11.1.1.1.2905 > 12.1.1.11.2905: sctp (1) [HB REQ] 18:02:41.361777 IP 11.1.1.1.2905 > 12.1.1.11.2905: sctp (1) [HB REQ] 18:02:41.661772 IP 11.1.1.1.2905 > 12.1.1.11.2905: sctp (1) [HB REQ] 18:02:41.961772 IP 11.1.1.1.2905 > 12.1.1.11.2905: sctp (1) [HB REQ] 18:02:42.161771 IP 11.1.1.1.2905 > 12.1.1.11.2905: sctp (1) [HB REQ] 18:02:42.461770 IP 11.1.1.1.2905 > 12.1.1.11.2905: sctp (1) [HB REQ] 18:02:42.675770 IP 11.1.1.1.2905 > 12.1.1.11.2905: sctp (1) [HB REQ] If we are using single homing, there is no problem on the SCTP communication. Below is the TCP trace on eth1 using sctp_test 18:09:55.356727 IP 12.1.1.1.2905 > 11.1.1.11.2905: sctp (1) [INIT] [init tag: 32516609] [rwnd: 102400] [OS: 16] [MIS: 16] [init TSN: 0] 18:09:55.356811 IP 11.1.1.11.2905 > 12.1.1.1.2905: sctp (1) [INIT ACK] [init tag: 3168861995] [rwnd: 131072] [OS: 10] [MIS: 16] [init TSN: 1877695021] 18:09:55.357727 IP 12.1.1.1.2905 > 11.1.1.11.2905: sctp (1) [COOKIE ECHO] 18:09:55.357788 IP 11.1.1.11.2905 > 12.1.1.1.2905: sctp (1) [COOKIE ACK] 18:09:55.358724 IP 12.1.1.1.2905 > 11.1.1.11.2905: sctp (1) [HB REQ] 18:09:55.358740 IP 11.1.1.11.2905 > 12.1.1.1.2905: sctp (1) [HB ACK] 18:09:55.379715 IP 12.1.1.1.2905 > 11.1.1.11.2905: sctp (1) [DATA] (B)(E) [TSN: 0] [SID: 0] [SSEQ 0] [PPID 0x3] 18:09:55.379735 IP 11.1.1.11.2905 > 12.1.1.1.2905: sctp (1) [SACK] [cum ack 0] [a_rwnd 131064] [#gap acks 0] [#dup tsns 0] 18:09:55.657716 IP 12.1.1.1.2905 > 11.1.1.11.2905: sctp (1) [HB REQ] 18:09:55.657732 IP 11.1.1.11.2905 > 12.1.1.1.2905: sctp (1) [HB ACK] >From the observations, it seems that the LKSCTP library is not able to use the original local address when multi-homing is being used. Is there anyway can be resolved it? Thanks PS -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
