CISC 856 Homework : Stream Control Transmission Protocol
Aparna Kailasam ()
Due : November 25, 2008
- Answer questions 4-7, 9-16 and 18 from Chapter 13 in textbook
- Take the online quiz, and submit results of the same to Dr. Amer at
- Explain the steps taken by an Endpoint A to monitor the reachability of idle destination addresses of Endpoint B.
- SACK chunk
Type = 3 / Flags = 0 / Length = variable
Cum Ack=1345678
rwnd = 64200
Number of gap ACK blocks = 2 / Number of Dup = 2
Gap ACK block 1 start= 2 / Gap ACK1 block end = 7
Gap ACK block 2 start = 9 / Gap ACK block 2 end = 14
Dulicate TSN = 1345671
Duplicate TSN = 1345675
Interpret the SACK chunk above. Can there be a Gap ACK block start of 1?
5. Analyze the following Wireshark Dump. The dump shows a capture done on a SCTP
association where a single web page with some embedded images is transferred. Only the relevant
parameters in the chunk have been mentioned.
Highlight the following in the dump and answer the questions:
- Association Establishment: (Highlight the chunk names, INIT tags,stateCookie, and the corresponding V-Tags with 4 different colors.)
- What is the purpose of the Verification tag in SCTP? What must an SCTP endpoint do when it receives a SCTP PDU with the Verification tag = 0?
- The Association Shutdown (Highlight the chunk names.)
- Show evidence of the application protocol is running over SCTP?
- What are the advantages of SCTP preservingA-PDU boundaries? Describe one application that can take advantage of this SCTP feature (that is, describe an application that would prefer SCTP over TCP because of this feature.)
SCTP Dump
No. Time Source Destination Protocol Info
1 0.000000 10.1.202.2 10.1.205.2 SCTP INIT
Frame 1 (154 bytes on wire, 154 bytes captured)
Ethernet II, Src: DellEsgP_66:3f:0b (00:0b:db:66:3f:0b), Dst: Netgear_1f:3e:e2 (00:09:5b:1f:3e:e2)
Internet Protocol, Src: 10.1.202.2 (10.1.202.2), Dst: 10.1.205.2 (10.1.205.2)
Stream Control Transmission Protocol, Src Port: 56060 (56060), Dst Port: 4000 (4000)
Source port: 56060
Destination port: 4000
Verification tag: 0x00000000
Checksum: 0xcf474439 [correct CRC32C]
INIT chunk (Outbound streams: 10, inbound streams: 10)
Chunk type: INIT (1)
Chunk flags: 0x00
Chunk length: 108
Initiate tag: 0xf66ab5f4
Advertised receiver window credit (a_rwnd): 384000
Number of outbound streams: 10
Number of inbound streams: 10
Initial TSN: 4207618671
No. Time Source Destination Protocol Info
2 0.000091 10.1.205.2 10.1.202.2 SCTP INIT_ACK
Frame 2 (478 bytes on wire, 478 bytes captured)
Ethernet II, Src: Netgear_1f:3e:e2 (00:09:5b:1f:3e:e2), Dst: DellEsgP_66:3f:0b (00:0b:db:66:3f:0b)
Internet Protocol, Src: 10.1.205.2 (10.1.205.2), Dst: 10.1.202.2 (10.1.202.2)
Stream Control Transmission Protocol, Src Port: 4000 (4000), Dst Port: 56060 (56060)
Source port: 4000
Destination port: 56060
Verification tag: 0xf66ab5f4
Checksum: 0xb823e0fc [correct CRC32C]
INIT_ACK chunk (Outbound streams: 10, inbound streams: 100)
Chunk type: INIT_ACK (2)
Chunk flags: 0x00
Chunk length: 432
Initiate tag: 0xfc4a6613
Advertised receiver window credit (a_rwnd): 384000
Number of outbound streams: 10
Number of inbound streams: 100
Initial TSN: 3522627716
State cookie parameter (Cookie length: 328 bytes)
Parameter type: State cookie (0x0007)
0...... = Bit: Stop processing of chunk
.0...... = Bit: Do not report
Parameter length: 332
State cookie: 4B414D452D42534420312E316F2666C03C00000000000000...
No. Time Source Destination Protocol Info
3 0.130937 10.1.202.2 10.1.205.2 SCTP COOKIE_ECHO DATA
Frame 3 (798 bytes on wire, 798 bytes captured)
Ethernet II, Src: DellEsgP_66:3f:0b (00:0b:db:66:3f:0b), Dst: Netgear_1f:3e:e2 (00:09:5b:1f:3e:e2)
Internet Protocol, Src: 10.1.202.2 (10.1.202.2), Dst: 10.1.205.2 (10.1.205.2)
Stream Control Transmission Protocol, Src Port: 56060 (56060), Dst Port: 4000 (4000)
Source port: 56060
Destination port: 4000
Verification tag: 0xfc4a6613
Checksum: 0x82480314 [correct CRC32C]
COOKIE_ECHO chunk (Cookie length: 328 bytes)
Chunk type: COOKIE_ECHO (10)
Chunk flags: 0x00
Chunk length: 332
Cookie: 4B414D452D42534420312E316F2666C03C00000000000000...
..
No. Time Source Destination Protocol Info
4 0.131110 10.1.205.2 10.1.202.2 SCTP COOKIE_ACK SACK
Frame 4 (66 bytes on wire, 66 bytes captured)
Ethernet II, Src: Netgear_1f:3e:e2 (00:09:5b:1f:3e:e2), Dst: DellEsgP_66:3f:0b (00:0b:db:66:3f:0b)
Internet Protocol, Src: 10.1.205.2 (10.1.205.2), Dst: 10.1.202.2 (10.1.202.2)
Stream Control Transmission Protocol, Src Port: 4000 (4000), Dst Port: 56060 (56060)
Source port: 4000
Destination port: 56060
Verification tag: 0xf66ab5f4
Checksum: 0x22459131 [correct CRC32C]
COOKIE_ACK chunk
Chunk type: COOKIE_ACK (11)
Chunk flags: 0x00
Chunk length: 4
SACK chunk (Cumulative TSN: 4207618671, a_rwnd: 383598, gaps: 0, duplicate TSNs: 0)
Chunk type: SACK (3)
Chunk flags: 0x01
Chunk length: 16
Cumulative TSN ACK: 4207618671
Advertised receiver window credit (a_rwnd): 383598
Number of gap acknowledgement blocks : 0
Number of duplicated TSNs: 0
No. Time Source Destination Protocol Info
5 0.131493 10.1.205.2 10.1.202.2 SCTP DATA
Frame 5 (342 bytes on wire, 342 bytes captured)
Ethernet II, Src: Netgear_1f:3e:e2 (00:09:5b:1f:3e:e2), Dst: DellEsgP_66:3f:0b (00:0b:db:66:3f:0b)
Internet Protocol, Src: 10.1.205.2 (10.1.205.2), Dst: 10.1.202.2 (10.1.202.2)
Stream Control Transmission Protocol, Src Port: 4000 (4000), Dst Port: 56060 (56060)
Source port: 4000
Destination port: 56060
Verification tag: 0xf66ab5f4
Checksum: 0xae7cf03a [correct CRC32C]
DATA chunk(ordered, complete segment, TSN: 3522627716, SID: 1, SSN: 0, PPID: 16777216, payload length: 278 bytes)
Chunk type: DATA (0)
Chunk flags: 0x03
Chunk length: 294
TSN: 3522627716
Stream Identifier: 0x0001
Stream sequence number: 0
Payload protocol identifier: Unknown (16777216)
Chunk padding: 0000
Data (278 bytes)
0000 48 54 54 50 2f 31 2e 31 20 32 30 30 20 4f 4b 0d HTTP/1.1 200 OK.
0010 0a 44 61 74 65 3a 20 4d 6f 6e 2c 20 31 32 20 4e .Date: Mon, 12 N
0020 6f 76 20 32 30 30 37 20 32 30 3a 32 33 3a 33 30 ov 2007 20:23:30
0030 20 47 4d 54 0d 0a 53 65 72 76 65 72 3a 20 41 70 GMT..Server: Ap
0040 61 63 68 65 2f 32 2e 30 2e 35 35 20 28 55 6e 69 ache/2.0.55 (Uni
.
.
.
.
No. Time Source Destination Protocol Info
22 8.842387 10.1.202.2 10.1.205.2 SCTP SHUTDOWN
Frame 22 (60 bytes on wire, 60 bytes captured)
Ethernet II, Src: DellEsgP_66:3f:0b (00:0b:db:66:3f:0b), Dst: Netgear_1f:3e:e2 (00:09:5b:1f:3e:e2)
Internet Protocol, Src: 10.1.202.2 (10.1.202.2), Dst: 10.1.205.2 (10.1.205.2)
Stream Control Transmission Protocol, Src Port: 56060 (56060), Dst Port: 4000 (4000)
Source port: 56060
Destination port: 4000
Verification tag: 0xfc4a6613
Checksum: 0xf3bb07cd [correct CRC32C]
SHUTDOWN chunk (Cumulative TSN ack: 3522627724)
Chunk type: SHUTDOWN (7)
Chunk flags: 0x00
Chunk length: 8
Cumulative TSN Ack: 3522627724
No. Time Source Destination Protocol Info
23 8.842439 10.1.205.2 10.1.202.2 SCTP SHUTDOWN_ACK
Frame 23 (50 bytes on wire, 50 bytes captured)
Ethernet II, Src: Netgear_1f:3e:e2 (00:09:5b:1f:3e:e2), Dst: DellEsgP_66:3f:0b (00:0b:db:66:3f:0b)
Internet Protocol, Src: 10.1.205.2 (10.1.205.2), Dst: 10.1.202.2 (10.1.202.2)
Stream Control Transmission Protocol, Src Port: 4000 (4000), Dst Port: 56060 (56060)
Source port: 4000
Destination port: 56060
Verification tag: 0xf66ab5f4
Checksum: 0x05b12342 [correct CRC32C]
SHUTDOWN_ACK chunk
Chunk type: SHUTDOWN_ACK (8)
Chunk flags: 0x00
Chunk length: 4
No. Time Source Destination Protocol Info
24 8.842511 10.1.205.2 10.1.202.2 SCTP SHUTDOWN
Frame 24 (54 bytes on wire, 54 bytes captured)
Ethernet II, Src: Netgear_1f:3e:e2 (00:09:5b:1f:3e:e2), Dst: DellEsgP_66:3f:0b (00:0b:db:66:3f:0b)
Internet Protocol, Src: 10.1.205.2 (10.1.205.2), Dst: 10.1.202.2 (10.1.202.2)
Stream Control Transmission Protocol, Src Port: 4000 (4000), Dst Port: 56060 (56060)
Source port: 4000
Destination port: 56060
Verification tag: 0xf66ab5f4
Checksum: 0x7f9c9c71 [correct CRC32C]
SHUTDOWN chunk (Cumulative TSN ack: 4207618673)
Chunk type: SHUTDOWN (7)
Chunk flags: 0x00
Chunk length: 8
Cumulative TSN Ack: 4207618673
No. Time Source Destination Protocol Info
25 8.964357 10.1.202.2 10.1.205.2 SCTP SHUTDOWN_COMPLETE
Frame 25 (60 bytes on wire, 60 bytes captured)
Ethernet II, Src: DellEsgP_66:3f:0b (00:0b:db:66:3f:0b), Dst: Netgear_1f:3e:e2 (00:09:5b:1f:3e:e2)
Internet Protocol, Src: 10.1.202.2 (10.1.202.2), Dst: 10.1.205.2 (10.1.205.2)
Stream Control Transmission Protocol, Src Port: 56060 (56060), Dst Port: 4000 (4000)
Source port: 56060
Destination port: 4000
Verification tag: 0xfc4a6613
Checksum: 0x8a11ba43 [correct CRC32C]
SHUTDOWN_COMPLETE chunk
Chunk type: SHUTDOWN_COMPLETE (14)
Chunk flags: 0x00
Chunk length: 4