The document provides a technical analysis of GPRS Tunneling Protocol (GTP) messages, detailing various requests and responses such as echo requests, create PDP context requests, and delete PDP context requests. Each message type includes specific attributes like source and destination ports, sequence numbers, and protocol flags. The analysis is sourced from Sakura Internet Research Center, highlighting the operations and functionalities within GTP communication protocols.

1. 08-Dec-2015
SAKURA Internet Research Center.
Senior Researcher / Naoto MATSUMOTO

2. GTP Connection Analysis 1/7
1) GTP : Echo request
User Datagram Protocol, Src Port: 2123 (2123), Dst Port: 2123 (2123)
GPRS Tunneling Protocol
Flags: 0x32
001. .... = Version: GTP release 99 version (1)
...1 .... = Protocol type: GTP (1)
.... 0... = Reserved: 0
.... .0.. = Is Next Extension Header present?: No
.... ..1. = Is Sequence Number present?: Yes
.... ...0 = Is N-PDU number present?: No
Message Type: Echo request (0x01)
Length: 4
TEID: 0x00000000
SOURCE: SAKURA Internet Research Center. 12/2015
NAT444
GGSN
SGSN
GTP
INTERNET

3. GTP Connection Analysis 2/7
2) GTP : Create PDP context request
User Datagram Protocol, Src Port: 2123 (2123), Dst Port: 2123 (2123)
GPRS Tunneling Protocol
Flags: 0x32
001. .... = Version: GTP release 99 version (1)
...1 .... = Protocol type: GTP (1)
.... 0... = Reserved: 0
.... .0.. = Is Next Extension Header present?: No
.... ..1. = Is Sequence Number present?: Yes
.... ...0 = Is N-PDU number present?: No
Message Type: Create PDP context request (0x10)
Length: 104
TEID: 0x00000000
Sequence number: 0x1401
IMSI: 240010123456789
Recovery: 5
.... ..01 = Selection mode: MS provided APN, subscription not verified (1)
TEID Data I: 0x00000001
TEID Control Plane: 0x00000001
NSAPI: 0
Charging characteristics: 2048
End user address (IETF/IPv4)
Access Point Name: test-apn
Protocol configuration options
GSN address : 10.0.0.50
GSN address : 10.0.0.50
MS international PSTN/ISDN number
Quality of Service
SOURCE: SAKURA Internet Research Center. 12/2015
NAT444
GGSN
SGSN
GTP
INTERNET

4. GTP Connection Analysis 3/7
3) GTP : Echo response
User Datagram Protocol, Src Port: 2123 (2123), Dst Port: 2123 (2123)
GPRS Tunneling Protocol
Flags: 0x32
001. .... = Version: GTP release 99 version (1)
...1 .... = Protocol type: GTP (1)
.... 0... = Reserved: 0
.... .0.. = Is Next Extension Header present?: No
.... ..1. = Is Sequence Number present?: Yes
.... ...0 = Is N-PDU number present?: No
Message Type: Echo response (0x02)
Length: 6
TEID: 0x00000000
Sequence number: 0x1400
Recovery: 9
SOURCE: SAKURA Internet Research Center. 12/2015
NAT444
GGSN
SGSN
GTP
INTERNET

5. GTP Connection Analysis 4/7
4) GTP : Create PDP context response Echo response
User Datagram Protocol, Src Port: 2123 (2123), Dst Port: 2123 (2123)
GPRS Tunneling Protocol
Flags: 0x32
001. .... = Version: GTP release 99 version (1)
...1 .... = Protocol type: GTP (1)
.... 0... = Reserved: 0
.... .0.. = Is Next Extension Header present?: No
.... ..1. = Is Sequence Number present?: Yes
.... ...0 = Is N-PDU number present?: No
Message Type: Create PDP context response (0x11)
Length: 78
TEID: 0x00000001
Sequence number: 0x1401
Cause: Request accepted (128)
Reordering required: False
Recovery: 9
TEID Data I: 0x00000001
TEID Control Plane: 0x00000001
Charging ID: 0x00000001
End user address (IETF/IPv4) : 192.168.0.2
Protocol configuration options
GSN address : 10.0.0.1
GSN address : 10.0.0.1
Quality of Service
SOURCE: SAKURA Internet Research Center. 12/2015
NAT444
GGSN
SGSN
GTP
INTERNET

6. GTP Connection Analysis 5/7
5) GTP : T-PDU <ICMP> 138 Echo (ping) request
User Datagram Protocol, Src Port: 2152 (2152), Dst Port: 2152 (2152)
GPRS Tunneling Protocol
Flags: 0x32
001. .... = Version: GTP release 99 version (1)
...1 .... = Protocol type: GTP (1)
.... 0... = Reserved: 0
.... .0.. = Is Next Extension Header present?: No
.... ..1. = Is Sequence Number present?: Yes
.... ...0 = Is N-PDU number present?: No
Message Type: T-PDU (0xff)
Length: 88
TEID: 0x00000001
Sequence number: 0x0000
T-PDU Data 80 bytes
Internet Protocol Version 4, Src: 192.168.0.2 (192.168.0.2), Dst: 192.168.11.43 (192.168.11.43)
Internet Control Message Protocol
SOURCE: SAKURA Internet Research Center. 12/2015
NAT444
GGSN
SGSN
T-PDU
GTP
INTERNET

7. GTP Connection Analysis 6/7
6) GTP : T-PDU <ICMP> 138 Echo (ping) reply
User Datagram Protocol, Src Port: 2152 (2152), Dst Port: 2152 (2152)
GPRS Tunneling Protocol
Flags: 0x32
001. .... = Version: GTP release 99 version (1)
...1 .... = Protocol type: GTP (1)
.... 0... = Reserved: 0
.... .0.. = Is Next Extension Header present?: No
.... ..1. = Is Sequence Number present?: Yes
.... ...0 = Is N-PDU number present?: No
Message Type: T-PDU (0xff)
Length: 88
TEID: 0x00000001
Sequence number: 0x0000
T-PDU Data 80 bytes
Internet Protocol Version 4, Src: 192.168.11.43 (192.168.11.43), Dst: 192.168.0.2 (192.168.0.2)
Internet Control Message Protocol
SOURCE: SAKURA Internet Research Center. 12/2015
NAT444
GGSN
SGSN
T-PDU
GTP
INTERNET

8. GTP Connection Analysis 7/7
7) GTP : Delete PDP context request / response
User Datagram Protocol, Src Port: 2123 (2123), Dst Port: 2123 (2123)
GPRS Tunneling Protocol
Flags: 0x32
001. .... = Version: GTP release 99 version (1)
...1 .... = Protocol type: GTP (1)
.... 0... = Reserved: 0
.... .0.. = Is Next Extension Header present?: No
.... ..1. = Is Sequence Number present?: Yes
.... ...0 = Is N-PDU number present?: No
Message Type: Delete PDP context request (0x14)
Length: 8
TEID: 0x00000001
Sequence number: 0x1402
:
GPRS Tunneling Protocol
Flags: 0x32
001. .... = Version: GTP release 99 version (1)
...1 .... = Protocol type: GTP (1)
.... 0... = Reserved: 0
.... .0.. = Is Next Extension Header present?: No
.... ..1. = Is Sequence Number present?: Yes
.... ...0 = Is N-PDU number present?: No
Message Type: Delete PDP context response (0x15)
Length: 6
TEID: 0x00000001
Sequence number: 0x1402
Cause: Request accepted (128)
SOURCE: SAKURA Internet Research Center. 12/2015
NAT444
GGSN
SGSN
GTP
INTERNET