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Feature #6115

open

modem: MTU not set properly on tun iface

Added by pespin 7 months ago. Updated 2 months ago.

Status:
Feedback
Priority:
Normal
Assignee:
Category:
OsmocomBB modem (host)
Target version:
Start date:
07/26/2023
Due date:
% Done:

0%

Resolution:
Spec Reference:
Tags:

Description

tested using iperf3 client in the netns + tun created by the "modem" app, against an iperf3 server running in the IP address of the GGSN outside the netns:

iperf3 -c 176.16.222.1 -u -V
iperf3 -s -B 176.16.222.1

The iperf3 tries to fill in the MTU when sending packets, but there seems to be a problem when enqueueing them:

20230726174215423 DLLC ERROR llc.c:359 LLE(c34b1498/c914945e,SNDCP3){ASSIGNED_ADM} Cannot Tx 1480 bytes (N201-U=500)
20230726174215433 DTUN DEBUG app_modem.c:121 APN(internet): system wants to transmit IPv4 pkt to 176.16.222.1 (1476 bytes)
20230726174215433 DSNDCP INFO sndcp_prim.c:424 Rx from upper layers: SN-UNITDATA.request
20230726174215434 DSNDCP DEBUG sndcp.c:130 modem_sndcp_prim_down_cb(): Rx LL-UNITDATA.request TLLI=0xc914945e SAPI=SNDCP3 L3=[66 00 05 d5 45 00 05 c4 78 bc 40 00 40 11 a0 47 b0 10 de 02 b0 10 de 01 aa 53 14 51 05 b0 3b dd 00 00 2a ed 00 0a f5 b0 00 00 01 8c 21 52 df 52 61 ce 27 d9 5b ea e8 ec 6d fe 02 45 1b 9c cc dc ec 38 8f e5 29 e9 b0 a0 1c 01 2b 3b 39 e1 9c 51 2f c5 79 14 de c8 b6 13 23 c5 b1 ff 79 d0 5e 1b 04 b2 4e 3f 90 a3 3a 00 df 13 ab 43 8c b7 d3 a8 45 39 a2 70 06 76 c1 fe 19 95 76 3a 74 51 18 6c 5c 4d c1 a0 4b 80 51 3d 73 c6 95 14 e3 76 f9 af 1c f4 28 70 0d 4e 78 21 83 32 a8 12 82 a6 76 01 f3 75 36 77 08 8d 0f 16 c7 be 7a 1b 51 bf 64 9b 0f fc c3 86 bd 1f 0a b0 8c 6f f7 d2 01 da 5b 07 72 72 66 4e 80 55 a6 77 86 bb 76 5c 9c 48 85 a3 5f 97 70 ce b0 ff 79 f9 e0 10 92 f3 e0 bc a0 ee d2 08 90 55 04 6c 8a 28 31 fb 00 66 24 54 67 36 c9 1d 0c 71 ff 09 52 7a 1b 4d 77 02 87 47 89 9f 62 ae da 4c 14 88 8b f5 cc 28 0a df 59 89 e2 72 64 28 dc 0e b2 59 10 57 ae 60 70 9c 31 ee 5d 55 c1 66 82 70 aa 4c 3b aa 79 45 8f e1 06 3c 68 66 8f 0b 86 90 4e 73 fd a9 f3 2e 9b 4a 3f 58 69 82 b1 c1 c2 4e af 5a dc d0 5b 6b 22 17 4f 74 8b 17 6e 0d 23 13 23 c2 1b f3 b0 56 ec fa 3b 48 98 bd 9b 7e e4 c9 a5 37 3f ed 05 d2 0e 0f f4 21 af 9e d0 83 31 70 12 8b 14 96 46 bf b9 3a 64 0a 75 da 0f 8d 83 d9 8a 9b 26 0b 4c 65 1d 26 f1 9e 75 08 8a 48 03 64 c0 a1 de d6 59 ad 9f 6b f6 cf 4a 65 08 cf 18 68 54 16 8f af 61 8c 06 fb 6a 09 93 c9 4a fb 00 94 16 9c 2f f3 a6 5e 90 55 29 7e 3a b9 04 2d 69 06 f7 89 2e 53 52 67 c4 73 43 05 9a ce af f9 7d 77 26 c1 a5 aa c8 8e 0f 80 c4 00 be 71 3f 1a f8 38 f1 4c 06 59 07 ac 06 32 eb 5a d2 35 db 3d 11 0c fa af 04 8c 56 d0 a8 3a 2f 50 9f cb 0d 44 10 38 f9 ab 79 97 0a 11 8a 21 4a d1 0d 4b 8c ea f4 79 2b ac f0 48 52 67 b8 36 05 1f 2e bb e4 c5 d1 8c 35 d4 8e fb 8d 8d 8d 15 26 fe 37 fd bb 6b af 2a b4 11 97 24 b0 28 15 ce 95 97 d5 7f 62 8b 73 77 d7 7f a6 72 23 35 fb 60 65 de 84 54 b9 a0 30 21 3e 87 f2 a7 9c 82 0c 92 6a 28 e4 06 6e 84 e9 6a 1c 20 5c 30 dd 1b 80 71 88 9f 5b 3b 74 2d 18 ed 6e f7 8c 67 ba ed 05 06 13 76 58 c0 7b 1b 1d d9 23 14 30 ef 97 4c 1d 48 a2 8e 83 49 1b 6b 75 90 b6 a0 98 e9 7d b1 c7 fa 39 6e a5 18 9a 94 ab 6d 18 d2 1f 61 39 a1 2e ca 7f b9 23 73 7d 29 a1 6a bd f6 9b e2 d9 cf fa 0f ca 46 c3 be 4a cc 7d 19 9e 23 be 74 65 7c cc e8 d7 f7 6c 8a 64 7b 0b 14 d3 b5 3f 19 47 94 08 70 23 02 01 2f 4d 09 07 4d 1f a6 6f b0 3b b3 7d 14 75 74 e5 1b 93 0a 52 0e 2a 02 e2 60 a9 dd 52 42 c9 c7 ee ab fb 7f fb 81 09 07 7a e7 64 1d bf 56 ad 68 c6 bc 73 81 a9 5a 03 4d 3f 02 66 73 87 01 11 dc f2 ab f9 a6 77 f2 db f3 4b 1f 32 05 4f ea 96 bc 7b e3 a5 e0 b4 de 3b ed 34 1f 95 9e ed f9 aa a6 ef 56 ea 17 a4 1a ad ea 64 8c f3 4b 05 a1 cd 31 92 82 c4 fa 43 07 f2 01 a4 9c e4 ae 4c cd ad f0 34 ec cb 4b 4d 3a b3 c1 3f b5 1f 0c 6a 8b d1 fb 2f 4e d6 59 c1 a3 61 1c cf 01 26 32 5b 97 a9 9a 31 16 b3 11 10 e6 ec 0f 74 d4 9e eb 57 ae 95 30 bc 8b 2f 41 fc fc 73 46 f8 1b 06 c6 b6 9c e7 a9 c3 13 2c 9d 93 f8 cc 61 d5 ff 09 4e 67 dc 79 60 80 67 00 86 83 d5 45 ad 5c f0 21 2b 81 29 98 19 85 cc 70 2c 43 0f bb 13 4d 31 41 5c 49 af d1 3d 82 fc 72 74 6b 81 a9 d4 d8 4a 75 8e 2c 54 f8 b1 1c 21 5e d6 f5 f8 0d 51 13 bc 6b 09 e9 d6 a0 bf 62 f8 b0 a7 64 39 fb 71 a1 b3 53 b9 c2 4c 9d 93 3a 78 9f 73 12 5f 3a f3 c7 73 73 20 bc 82 59 79 f2 b5 b7 13 43 0e 73 f7 fd 4a df 51 9b 44 78 e7 7f 18 5a a0 fb 88 94 e6 3a 27 23 bf e7 10 bb 50 6e 4d 59 a9 9c 83 ca 67 d7 60 92 99 e5 5e a4 86 42 7e 7b 3a b7 4b c0 4f 85 71 52 0c 42 35 30 46 e8 62 85 96 42 d8 77 5c 9a f8 ab 74 52 a8 17 03 cf 16 34 18 fb e1 85 00 83 e8 b1 83 0e 4f 43 25 40 b5 29 2c e1 c1 8f 61 0d a2 63 2e 41 06 97 66 1a a6 38 db f4 bc 0d 70 c7 af 53 cd e6 be 00 bc 2b df 2a 15 98 dc 05 30 cd 25 bd 0f 59 74 ba cd ba 2d 67 c3 69 c4 72 00 40 76 7e 0f d9 95 bc 25 34 e6 30 89 f6 fa 6e d4 10 98 2d 32 b5 91 2e 4a e6 01 0f e2 34 d5 0f 91 b6 cb 49 e1 d2 86 6c 9b d4 06 16 59 93 86 68 d5 01 0b 47 ac 4b 92 fa a1 5d f4 46 a4 bc 89 3b 06 54 be e4 77 b6 0d 89 47 9d 70 9b 97 9e 0b 04 03 88 96 1b 63 31 81 3d 6d da 86 c8 a6 af 43 31 1f 99 7f da fa b9 44 a2 6c 31 ff 1d 3d 41 67 78 9f bb e3 2b 8b 7c dc 20230726174215434 DLLC INFO llc_prim.c:157 Rx from upper layers: LL-UNITDATA.request
20230726174215434 DLLC ERROR llc.c:359 LLE(c34b1498/c914945e,SNDCP3){ASSIGNED_ADM} Cannot Tx 1480 bytes (N201-U=500)
20230726174215441 DRLCMAC INFO rlcmac.c:789 TS=6 FN=93231 Rx Pkt DL Dummy Ctrl Block
20230726174215444 DTUN DEBUG app_modem.c:121 APN(internet): system wants to transmit IPv4 pkt to 176.16.222.1 (1476 bytes)
20230726174215445 DSNDCP INFO sndcp_prim.c:424 Rx from upper layers: SN-UNITDATA.request
20230726174215445 DSNDCP DEBUG sndcp.c:130 modem_sndcp_prim_down_cb(): Rx LL-UNITDATA.request TLLI=0xc914945e SAPI=SNDCP3 L3=[66 00 05 d6 45 00 05 c4 78 bd 40 00 40 11 a0 46 b0 10 de 02 b0 10 de 01 aa 53 14 51 05 b0 10 db 00 00 2a ed 00 0b 20 b1 00 00 01 8d 21 52 df 52 61 ce 27 d9 5b ea e8 ec 6d fe 02 45 1b 9c cc dc ec 38 8f e5 29 e9 b0 a0 1c 01 2b 3b 39 e1 9c 51 2f c5 79 14 de c8 b6 13 23 c5 b1 ff 79 d0 5e 1b 04 b2 4e 3f 90 a3 3a 00 df 13 ab 43 8c b7 d3 a8 45 39 a2 70 06 76 c1 fe 19 95 76 3a 74 51 18 6c 5c 4d c1 a0 4b 80 51 3d 73 c6 95 14 e3 76 f9 af 1c f4 28 70 0d 4e 78 21 83 32 a8 12 82 a6 76 01 f3 75 36 77 08 8d 0f 16 c7 be 7a 1b 51 bf 64 9b 0f fc c3 86 bd 1f 0a b0 8c 6f f7 d2 01 da 5b 07 72 72 66 4e 80 55 a6 77 86 bb 76 5c 9c 48 85 a3 5f 97 70 ce b0 ff 79 f9 e0 10 92 f3 e0 bc a0 ee d2 08 90 55 04 6c 8a 28 31 fb 00 66 24 54 67 36 c9 1d 0c 71 ff 09 52 7a 1b 4d 77 02 87 47 89 9f 62 ae da 4c 14 88 8b f5 cc 28 0a df 59 89 e2 72 64 28 dc 0e b2 59 10 57 ae 60 70 9c 31 ee 5d 55 c1 66 82 70 aa 4c 3b aa 79 45 8f e1 06 3c 68 66 8f 0b 86 90 4e 73 fd a9 f3 2e 9b 4a 3f 58 69 82 b1 c1 c2 4e af 5a dc d0 5b 6b 22 17 4f 74 8b 17 6e 0d 23 13 23 c2 1b f3 b0 56 ec fa 3b 48 98 bd 9b 7e e4 c9 a5 37 3f ed 05 d2 0e 0f f4 21 af 9e d0 83 31 70 12 8b 14 96 46 bf b9 3a 64 0a 75 da 0f 8d 83 d9 8a 9b 26 0b 4c 65 1d 26 f1 9e 75 08 8a 48 03 64 c0 a1 de d6 59 ad 9f 6b f6 cf 4a 65 08 cf 18 68 54 16 8f af 61 8c 06 fb 6a 09 93 c9 4a fb 00 94 16 9c 2f f3 a6 5e 90 55 29 7e 3a b9 04 2d 69 06 f7 89 2e 53 52 67 c4 73 43 05 9a ce af f9 7d 77 26 c1 a5 aa c8 8e 0f 80 c4 00 be 71 3f 1a f8 38 f1 4c 06 59 07 ac 06 32 eb 5a d2 35 db 3d 11 0c fa af 04 8c 56 d0 a8 3a 2f 50 9f cb 0d 44 10 38 f9 ab 79 97 0a 11 8a 21 4a d1 0d 4b 8c ea f4 79 2b ac f0 48 52 67 b8 36 05 1f 2e bb e4 c5 d1 8c 35 d4 8e fb 8d 8d 8d 15 26 fe 37 fd bb 6b af 2a b4 11 97 24 b0 28 15 ce 95 97 d5 7f 62 8b 73 77 d7 7f a6 72 23 35 fb 60 65 de 84 54 b9 a0 30 21 3e 87 f2 a7 9c 82 0c 92 6a 28 e4 06 6e 84 e9 6a 1c 20 5c 30 dd 1b 80 71 88 9f 5b 3b 74 2d 18 ed 6e f7 8c 67 ba ed 05 06 13 76 58 c0 7b 1b 1d d9 23 14 30 ef 97 4c 1d 48 a2 8e 83 49 1b 6b 75 90 b6 a0 98 e9 7d b1 c7 fa 39 6e a5 18 9a 94 ab 6d 18 d2 1f 61 39 a1 2e ca 7f b9 23 73 7d 29 a1 6a bd f6 9b e2 d9 cf fa 0f ca 46 c3 be 4a cc 7d 19 9e 23 be 74 65 7c cc e8 d7 f7 6c 8a 64 7b 0b 14 d3 b5 3f 19 47 94 08 70 23 02 01 2f 4d 09 07 4d 1f a6 6f b0 3b b3 7d 14 75 74 e5 1b 93 0a 52 0e 2a 02 e2 60 a9 dd 52 42 c9 c7 ee ab fb 7f fb 81 09 07 7a e7 64 1d bf 56 ad 68 c6 bc 73 81 a9 5a 03 4d 3f 02 66 73 87 01 11 dc f2 ab f9 a6 77 f2 db f3 4b 1f 32 05 4f ea 96 bc 7b e3 a5 e0 b4 de 3b ed 34 1f 95 9e ed f9 aa a6 ef 56 ea 17 a4 1a ad ea 64 8c f3 4b 05 a1 cd 31 92 82 c4 fa 43 07 f2 01 a4 9c e4 ae 4c cd ad f0 34 ec cb 4b 4d 3a b3 c1 3f b5 1f 0c 6a 8b d1 fb 2f 4e d6 59 c1 a3 61 1c cf 01 26 32 5b 97 a9 9a 31 16 b3 11 10 e6 ec 0f 74 d4 9e eb 57 ae 95 30 bc 8b 2f 41 fc fc 73 46 f8 1b 06 c6 b6 9c e7 a9 c3 13 2c 9d 93 f8 cc 61 d5 ff 09 4e 67 dc 79 60 80 67 00 86 83 d5 45 ad 5c f0 21 2b 81 29 98 19 85 cc 70 2c 43 0f bb 13 4d 31 41 5c 49 af d1 3d 82 fc 72 74 6b 81 a9 d4 d8 4a 75 8e 2c 54 f8 b1 1c 21 5e d6 f5 f8 0d 51 13 bc 6b 09 e9 d6 a0 bf 62 f8 b0 a7 64 39 fb 71 a1 b3 53 b9 c2 4c 9d 93 3a 78 9f 73 12 5f 3a f3 c7 73 73 20 bc 82 59 79 f2 b5 b7 13 43 0e 73 f7 fd 4a df 51 9b 44 78 e7 7f 18 5a a0 fb 88 94 e6 3a 27 23 bf e7 10 bb 50 6e 4d 59 a9 9c 83 ca 67 d7 60 92 99 e5 5e a4 86 42 7e 7b 3a b7 4b c0 4f 85 71 52 0c 42 35 30 46 e8 62 85 96 42 d8 77 5c 9a f8 ab 74 52 a8 17 03 cf 16 34 18 fb e1 85 00 83 e8 b1 83 0e 4f 43 25 40 b5 29 2c e1 c1 8f 61 0d a2 63 2e 41 06 97 66 1a a6 38 db f4 bc 0d 70 c7 af 53 cd e6 be 00 bc 2b df 2a 15 98 dc 05 30 cd 25 bd 0f 59 74 ba cd ba 2d 67 c3 69 c4 72 00 40 76 7e 0f d9 95 bc 25 34 e6 30 89 f6 fa 6e d4 10 98 2d 32 b5 91 2e 4a e6 01 0f e2 34 d5 0f 91 b6 cb 49 e1 d2 86 6c 9b d4 06 16 59 93 86 68 d5 01 0b 47 ac 4b 92 fa a1 5d f4 46 a4 bc 89 3b 06 54 be e4 77 b6 0d 89 47 9d 70 9b 97 9e 0b 04 03 88 96 1b 63 31 81 3d 6d da 86 c8 a6 af 43 31 1f 99 7f da fa b9 44 a2 6c 31 ff 1d 3d 41 67 78 9f bb e3 2b 8b 7c dc 20230726174215445 DLLC INFO llc_prim.c:157 Rx from upper layers: LL-UNITDATA.request
20230726174215445 DLLC ERROR llc.c:359 LLE(c34b1498/c914945e,SNDCP3){ASSIGNED_ADM} Cannot Tx 1480 bytes (N201-U=500)
20230726174215453 DTUN DEBUG app_modem.c:121 APN(internet): system wants to transmit IPv4 pkt to 176.16.222.1 (53 bytes)

These are all inside the netns used by "modem":

# ip addr
1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
3: modem4: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN group default qlen 500
    link/none
    inet 176.16.222.3/30 scope global modem4
       valid_lft forever preferred_lft forever
    inet6 fe80::75d:7419:9433:6fee/64 scope link stable-privacy proto kernel_ll
       valid_lft forever preferred_lft forever

# ip l
1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
3: modem4: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN mode DEFAULT group default qlen 500
    link/none

"Activate PDP Context Accept" sent to the MS contains:

Maximum SDU size: 1520 octets (153)


Related issues

Related to OsmocomBB - Feature #5503: expose GPRS user plane via tun deviceFeedbackpespin03/29/2022

Actions
Related to OsmoGGSN (former OpenGGSN) - Feature #6298: osmo-ggsn not providing MTU of the GTP tunnel to the MSNew12/08/2023

Actions
Actions #1

Updated by pespin 7 months ago

LLC XID transmitted SGSN -> MS contains:

MS-SGSN LLC (Mobile Station - Serving GPRS Support Node Logical Link Control)  SAPI: User data 3
    Address field  SAPI: LL3
        0... .... = Protocol Discriminator_bit: OK
        .1.. .... = Command/Response bit: DownLink/UpLink = Command/Response
        .... 0011 = SAPI: User data 3 (3)
    Unnumbered frame: XID
        111. .... = U format: 0x7
        ...1 .... = P/F bit: True
        .... 1011 = Command/Response: XID (0xb)
    FCS: 0x4e7c8c (correct)
    Information Field: Length = 8
        XID Parameter Type: Version (LLC version number) - Value: 0
            0... .... = XL Bit: 0x0
            .000 00.. = Type: 0
            .... ..01 = Length: 1
            0000 0000 = Parameter Byte: 0x00
        XID Parameter Type: N201-U (max info field length for U and UI frames) - Value: 500
            0... .... = XL Bit: 0x0
            .001 01.. = Type: 5
            .... ..10 = Length: 2
            0000 0001 = Parameter Byte: 0x01
            1111 0100 = Parameter Byte: 0xf4
        XID Parameter Type: N201-I (max info field length for I frames) - Value: 1503
            0... .... = XL Bit: 0x0
            .001 10.. = Type: 6
            .... ..10 = Length: 2
            0000 0101 = Parameter Byte: 0x05
            1101 1111 = Parameter Byte: 0xdf

Actions #2

Updated by pespin 7 months ago

It seems we are missing 2 things here to work properly:
  • Answer the LLC XID overwriting N201-U=500 to a bigger value
  • Adapt the tun iface MTU to the same value
Actions #3

Updated by pespin 7 months ago

As a reference, configuring ipoerf3 to use TCP and forcing a lower MSS (less than N201-U) seems to be working more or less fine:

# iperf3 -c 176.16.222.1 --set-mss 300
Connecting to host 176.16.222.1, port 5201
[  5] local 176.16.222.2 port 55386 connected to 176.16.222.1 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  34.6 KBytes   283 Kbits/sec    0   3.38 KBytes
[  5]   1.00-2.00   sec  0.00 Bytes  0.00 bits/sec    0   4.50 KBytes
[  5]   2.00-3.00   sec  0.00 Bytes  0.00 bits/sec    0   5.62 KBytes
[  5]   3.00-4.00   sec  0.00 Bytes  0.00 bits/sec    0   6.75 KBytes
[  5]   4.00-5.00   sec  0.00 Bytes  0.00 bits/sec    0   6.75 KBytes
[  5]   5.00-6.00   sec  0.00 Bytes  0.00 bits/sec    0   6.75 KBytes
[  5]   6.00-7.00   sec  0.00 Bytes  0.00 bits/sec    0   7.59 KBytes
[  5]   7.00-8.00   sec  0.00 Bytes  0.00 bits/sec    0   7.88 KBytes
[  5]   8.00-9.00   sec  0.00 Bytes  0.00 bits/sec    0   8.44 KBytes
[  5]   9.00-10.00  sec  0.00 Bytes  0.00 bits/sec    0   9.00 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  34.6 KBytes  28.3 Kbits/sec    0             sender
[  5]   0.00-17.72  sec  19.1 KBytes  8.84 Kbits/sec                  receiver

Actions #4

Updated by pespin 7 months ago

pespin wrote in #note-2:

Answer the LLC XID overwriting N201-U=500 to a bigger value

I see that we are actually answering with an XID MS -> SGSN, but it contains the same values that were requested.

Actions #5

Updated by pespin 7 months ago

  • Status changed from New to Feedback

The N201 values actually have nothing to do with MTU, but with LLC segments, where max segment size can be smaller than MTU.

N201 forwarding LLC -> SNDCP code was missing, I submitted it to libosmo-gprs-rlcmac around these patches:
remote: https://gerrit.osmocom.org/c/libosmo-gprs/+/33947 llc: Introduce function to log XID fields and use upon Rx/Tx
remote: https://gerrit.osmocom.org/c/libosmo-gprs/+/33948 llc: Apply N201-I & N201-U requested by the network
remote: https://gerrit.osmocom.org/c/libosmo-gprs/+/33949 llc: Submit LL-XID-IND to L3 if N201-U or N201-I changes
remote: https://gerrit.osmocom.org/c/libosmo-gprs/+/33950 sndcp: Update n201_u & n201_i indicatd by LLC layer
remote: https://gerrit.osmocom.org/c/libosmo-gprs/+/33952 sndcp: Initialize N201-U & N201-I to default settings

After those are used, iperf3 is capable to transmit bigger IP packets. I had to cap the amount of data set though (150K), otherwise it clogs the socket and it's too much data to be sent over the GPRS link using only 1 TS:

# iperf3 -c 176.16.222.1 -u -V -n 150K
iperf 3.14
Linux pespin-thinkpad 6.4.4-arch1-1 #1 SMP PREEMPT_DYNAMIC Wed, 19 Jul 2023 19:19:38 +0000 x86_64
Control connection MSS 1448
Setting UDP block size to 1448
Time: Wed, 26 Jul 2023 19:08:12 GMT
Connecting to host 176.16.222.1, port 5201
      Cookie: wmx7r6lztnj2vjb2kih6darkprex4m5cy7ws
      Target Bitrate: 1048576
[  5] local 176.16.222.2 port 50442 connected to 176.16.222.1 port 5201
Starting Test: protocol: UDP, 1 streams, 1448 byte blocks, omitting 0 seconds, 153600 bytes to send, tos 0
[ ID] Interval           Transfer     Bitrate         Total Datagrams
[  5]   0.00-1.00   sec   129 KBytes  1.05 Mbits/sec  91
[  5]   1.00-1.17   sec  22.6 KBytes  1.08 Mbits/sec  16
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval           Transfer     Bitrate         Jitter    Lost/Total Datagrams
[  5]   0.00-1.17   sec   151 KBytes  1.06 Mbits/sec  0.000 ms  0/107 (0%)  sender
[  5]   0.00-90.68  sec   151 KBytes  13.7 Kbits/sec  830.780 ms  0/107 (0%)  receiver
CPU Utilization: local/sender 5.2% (2.4%u/2.8%s), remote/receiver 0.0% (0.0%u/0.0%s)

iperf Done.

Actions #6

Updated by pespin 6 months ago

We still probably want to ask for MTU through PCO (IIRC it is possible?) and apply it on the tun interface.

Actions #7

Updated by fixeria 6 months ago

  • Tags set to ARDC
  • Category changed from OsmocomBB mobile (host) to OsmocomBB modem (host)
Actions #8

Updated by fixeria 5 months ago

  • Parent task deleted (#5500)
Actions #9

Updated by fixeria 5 months ago

  • Related to Feature #5503: expose GPRS user plane via tun device added
Actions #10

Updated by pespin 2 months ago

MTU is provided by PCO in IPv4 and through SLAAC in IPv6 (see https://github.com/open5gs/open5gs/issues/2754 for more info).
I think osmo-ggsn is not yet providing it to the MS, hence why one may not see it while looking at pcaps.

Actions #11

Updated by pespin 2 months ago

  • Related to Feature #6298: osmo-ggsn not providing MTU of the GTP tunnel to the MS added
Actions

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