SCTP Abort case-TCB destroyed

<[email protected]>
Newsgroups gmane.ietf.sigtran
Message-ID <[email protected]> 
Hi sigtran gurus,

I am seeing this in an ASP-SGP scenario 

EndPoint A		EndPoint B
SCTP-INIT------------------->
	<----------------------INIT_ACK
COOKIE-ECHO----------->
	<---------------------SCTP-ABORT

In the ABORT CHUNK I see the T-Bit set to 0 (TCB destroyed). 

I have attached the above four packets expanded in a text file for your
reference.

 <<sctp_abort_case.txt>> 
Why is the ABORT being sent in this case?

Is it being treated as an OOTB packet?

Thanks                                                    

Edwin

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sctp_abort_case.txt (text/plain, 9.5 KB) 
Frame 46 (82 bytes on wire, 82 bytes captured)
    Arrival Time: Apr  3, 2006 19:37:02.009000000
    Time delta from previous packet: 2.002000000 seconds
    Time since reference or first frame: 94.009000000 seconds
    Frame Number: 46
    Packet Length: 82 bytes
    Capture Length: 82 bytes
Ethernet II, Src: 00:00:50:19:d6:35, Dst: 00:14:6a:fd:35:20
    Destination: 00:14:6a:fd:35:20 (00:14:6a:fd:35:20)
    Source: 00:00:50:19:d6:35 (Radisys_19:d6:35)
    Type: IP (0x0800)
Internet Protocol, Src Addr: 10.13.65.147 (10.13.65.147), Dst Addr: 10.187.25.212 (10.187.25.212)
    Version: 4
    Header length: 20 bytes
    Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
        0000 00.. = Differentiated Services Codepoint: Default (0x00)
        .... ..0. = ECN-Capable Transport (ECT): 0
        .... ...0 = ECN-CE: 0
    Total Length: 68
    Identification: 0x7342 (29506)
    Flags: 0x00
        0... = Reserved bit: Not set
        .0.. = Don't fragment: Not set
        ..0. = More fragments: Not set
    Fragment offset: 0
    Time to live: 64
    Protocol: SCTP (0x84)
    Header checksum: 0x96c5 (correct)
    Source: 10.13.65.147 (10.13.65.147)
    Destination: 10.187.25.212 (10.187.25.212)
Stream Control Transmission Protocol
    Source port: 49152
    Destination port: 2905
    Verification tag: 0x00000000
    Checksum: 0xfcb753be (correct CRC32C)
    INIT chunk (Outbound streams: 2, inbound streams: 2048)
        Chunk type: INIT (1)
            0... .... = Bit: Stop processing of the packet
            .0.. .... = Bit: Do not report
        Chunk flags: 0x00
        Chunk length: 36
        Initiate tag: 0x81c50711
        Advertised receiver window credit (a_rwnd): 134656
        Number of outbound streams: 2
        Number of inbound streams: 2048
        Initial TSN: 3132905688
        Supported address types parameter (Supported types: IPv4, IPv6)
            Parameter type: Supported address types (0x000c)
                0... .... .... .... = Bit: Stop processing of chunk
                .0.. .... .... .... = Bit: Do not report
            Parameter length: 8
            Supported address type: IPv4 address (5)
            Supported address type: IPv6 address (6)
        ECN parameter
            Parameter type: ECN (0x8000)
                1... .... .... .... = Bit: Skip parameter and continue prosessing of the chunk
                .0.. .... .... .... = Bit: Do not report
            Parameter length: 4
        Forward TSN supported parameter
            Parameter type: Forward TSN supported (0xc000)
                1... .... .... .... = Bit: Skip parameter and continue prosessing of the chunk
                .1.. .... .... .... = Bit: Do report
            Parameter length: 4

Frame 47 (458 bytes on wire, 458 bytes captured)
    Arrival Time: Apr  3, 2006 19:37:02.029000000
    Time delta from previous packet: 0.020000000 seconds
    Time since reference or first frame: 94.029000000 seconds
    Frame Number: 47
    Packet Length: 458 bytes
    Capture Length: 458 bytes
Ethernet II, Src: 00:14:6a:fd:35:20, Dst: 00:00:50:19:d6:35
    Destination: 00:00:50:19:d6:35 (Radisys_19:d6:35)
    Source: 00:14:6a:fd:35:20 (00:14:6a:fd:35:20)
    Type: IP (0x0800)
Internet Protocol, Src Addr: 10.187.25.212 (10.187.25.212), Dst Addr: 10.13.65.147 (10.13.65.147)
    Version: 4
    Header length: 20 bytes
    Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
        0000 00.. = Differentiated Services Codepoint: Default (0x00)
        .... ..0. = ECN-Capable Transport (ECT): 0
        .... ...0 = ECN-CE: 0
    Total Length: 444
    Identification: 0x79e9 (31209)
    Flags: 0x04
        0... = Reserved bit: Not set
        .1.. = Don't fragment: Set
        ..0. = More fragments: Not set
    Fragment offset: 0
    Time to live: 61
    Protocol: SCTP (0x84)
    Header checksum: 0x51a6 (correct)
    Source: 10.187.25.212 (10.187.25.212)
    Destination: 10.13.65.147 (10.13.65.147)
Stream Control Transmission Protocol
    Source port: 2905
    Destination port: 49152
    Verification tag: 0x81c50711
    Checksum: 0x45fd0fd4 (correct CRC32C)
    INIT_ACK chunk (Outbound streams: 10, inbound streams: 2)
        Chunk type: INIT_ACK (2)
            0... .... = Bit: Stop processing of the packet
            .0.. .... = Bit: Do not report
        Chunk flags: 0x00
        Chunk length: 412
        Initiate tag: 0x0d794fb2
        Advertised receiver window credit (a_rwnd): 16384
        Number of outbound streams: 10
        Number of inbound streams: 2
        Initial TSN: 226054066
        State cookie parameter (Cookie length: 360 bytes)
            Parameter type: State cookie (0x0007)
                0... .... .... .... = Bit: Stop processing of chunk
                .0.. .... .... .... = Bit: Do not report
            Parameter length: 364
            State cookie: 81C5071100020E00000A000FBABC58D8...
        IPv4 address parameter (Address: 10.187.25.196)
            Parameter type: IPv4 address (0x0005)
                0... .... .... .... = Bit: Stop processing of chunk
                .0.. .... .... .... = Bit: Do not report
            Parameter length: 8
            IP Version 4 address: 10.187.25.196 (10.187.25.196)
        IPv4 address parameter (Address: 10.187.25.212)
            Parameter type: IPv4 address (0x0005)
                0... .... .... .... = Bit: Stop processing of chunk
                .0.. .... .... .... = Bit: Do not report
            Parameter length: 8
            IP Version 4 address: 10.187.25.212 (10.187.25.212)
        Unrecognized parameter parameter
            Parameter type: Unrecognized parameter (0x0008)
                0... .... .... .... = Bit: Stop processing of chunk
                .0.. .... .... .... = Bit: Do not report
            Parameter length: 12
            Forward TSN supported parameter
                Parameter type: Forward TSN supported (0xc000)
                    1... .... .... .... = Bit: Skip parameter and continue prosessing of the chunk
                    .1.. .... .... .... = Bit: Do report
                Parameter length: 4
                Parameter padding: 80000004

Frame 48 (410 bytes on wire, 410 bytes captured)
    Arrival Time: Apr  3, 2006 19:37:02.029000000
    Time delta from previous packet: 0.000000000 seconds
    Time since reference or first frame: 94.029000000 seconds
    Frame Number: 48
    Packet Length: 410 bytes
    Capture Length: 410 bytes
Ethernet II, Src: 00:00:50:19:d6:35, Dst: 00:14:6a:fd:35:20
    Destination: 00:14:6a:fd:35:20 (00:14:6a:fd:35:20)
    Source: 00:00:50:19:d6:35 (Radisys_19:d6:35)
    Type: IP (0x0800)
Internet Protocol, Src Addr: 10.13.65.147 (10.13.65.147), Dst Addr: 10.187.25.212 (10.187.25.212)
    Version: 4
    Header length: 20 bytes
    Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
        0000 00.. = Differentiated Services Codepoint: Default (0x00)
        .... ..0. = ECN-Capable Transport (ECT): 0
        .... ...0 = ECN-CE: 0
    Total Length: 396
    Identification: 0x7344 (29508)
    Flags: 0x04
        0... = Reserved bit: Not set
        .1.. = Don't fragment: Set
        ..0. = More fragments: Not set
    Fragment offset: 0
    Time to live: 64
    Protocol: SCTP (0x84)
    Header checksum: 0x557b (correct)
    Source: 10.13.65.147 (10.13.65.147)
    Destination: 10.187.25.212 (10.187.25.212)
Stream Control Transmission Protocol
    Source port: 49152
    Destination port: 2905
    Verification tag: 0x0d794fb2
    Checksum: 0x28231f87 (correct CRC32C)
    COOKIE_ECHO chunk (Cookie length: 360 bytes)
        Chunk type: COOKIE_ECHO (10)
            0... .... = Bit: Stop processing of the packet
            .0.. .... = Bit: Do not report
        Chunk flags: 0x00
        Chunk length: 364
        Cookie: 81C5071100020E00000A000FBABC58D8...

Frame 49 (60 bytes on wire, 60 bytes captured)
    Arrival Time: Apr  3, 2006 19:37:02.049000000
    Time delta from previous packet: 0.020000000 seconds
    Time since reference or first frame: 94.049000000 seconds
    Frame Number: 49
    Packet Length: 60 bytes
    Capture Length: 60 bytes
Ethernet II, Src: 00:14:6a:fd:35:20, Dst: 00:00:50:19:d6:35
    Destination: 00:00:50:19:d6:35 (Radisys_19:d6:35)
    Source: 00:14:6a:fd:35:20 (00:14:6a:fd:35:20)
    Type: IP (0x0800)
    Trailer: 00000000000000000000
Internet Protocol, Src Addr: 10.187.25.212 (10.187.25.212), Dst Addr: 10.13.65.147 (10.13.65.147)
    Version: 4
    Header length: 20 bytes
    Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
        0000 00.. = Differentiated Services Codepoint: Default (0x00)
        .... ..0. = ECN-Capable Transport (ECT): 0
        .... ...0 = ECN-CE: 0
    Total Length: 36
    Identification: 0x79ea (31210)
    Flags: 0x04
        0... = Reserved bit: Not set
        .1.. = Don't fragment: Set
        ..0. = More fragments: Not set
    Fragment offset: 0
    Time to live: 61
    Protocol: SCTP (0x84)
    Header checksum: 0x533d (correct)
    Source: 10.187.25.212 (10.187.25.212)
    Destination: 10.13.65.147 (10.13.65.147)
Stream Control Transmission Protocol
    Source port: 2905
    Destination port: 49152
    Verification tag: 0x81c50711
    Checksum: 0xc7fc32fd (correct CRC32C)
    ABORT chunk
        Chunk type: ABORT (6)
            0... .... = Bit: Stop processing of the packet
            .0.. .... = Bit: Do not report
        Chunk flags: 0x00
            .... ...0 = T-Bit: TCB destroyed
        Chunk length: 4
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