Document for network debugging

[miaoski]

Hi.

I'd like to write a easy debugging guild with regard to network topology. Not sure whether my understanding is correct, though. I'm posting my note here. If anything is wrong, please kindly tell me. I plan to write it in the weekend.

(IP are examples, ens3 is external facing NIC)

• HSS
  • listens 127.0.0.4:3868 ← MME (S6a)
  • listens 127.0.0.4:5868
  • diameter → MME:3868 (S6a)
• MME
  • listens 127.0.0.2:3868 ← HSS (S6a)
  • diameter → HSS:3868 (S6a)
  • MME.S1AP (S1AP server) listens to ens3:36412 ← srsENB (S1AP)
  • MME.GTPC (GTP server) listens to ens3:2123 ← srsENB (S1-MME)
  • → SGW:2123 (S11)
  • → SGSAP if you have CSFB
  • Tells eNB where to find SGW (sgw.gptc.addr)
  • Tells eNB where to find PGW (pgw.gtpc.addr)
• PCRF
  • listens 127.0.0.5:3868 ← PGW, P-CSCF
  • listens 127.0.0.5:5868
  • diameter → PGW (127.0.0.3)
  • → P-CSCF (10.4.128.21:3871)
• PGW
  • listens 127.0.0.3:3868
  • listens 127.0.0.3:5868
  • PGW.GTPC (GTP server) listens 127.0.0.3:2123 ← SGW (S5C)
  • PGW.GTPU (GTP server) listens 127.0.0.3:2152 ← SGW (S5U), eNB (?)
  • diameter → PCRF:3868
  • → P-CSCF (10.4.128.21)
  • → SGW:2152 (S5U)
• SGW
  • SGW.GTPC (GTP server) listens 127.0.0.2:2123 ← MME (S11)
  • SGW.GTPU (GTP server) listens 127.0.0.2:2152 ← PGW (S5U) (!) This is not S1-U
  • → PGW:2123 (S5C)
  • → PGW:2152 (S5U)
  • → eNB:2152 (S1-U) (?) MME tells SGW the IP of eNB?
• srsENB
  • GTP listens on ens3 (S1-U to SGW)
  • S1C → MME.GTPC (S1-MME to MME:2123)
  • eNB-S1 → MME.S1AP (S1AP to MME:36412)
• P-CSCF
  • listens 10.4.128.21:3871 ← PCRF
  • → PCRF:3868
• I-CSCF
  • listens 10.4.128.21:3869 ← FHoSS
  • → FHoSS:3868
• S-CSCF
  • listens 10.4.128.21:3870 ← FHoSS
  • → FHoSS:3868
• FHoSS
  • listens 10.4.128.21:3868 ← I-CSCF, S-CSCF
  • listens 10.4.128.21:8080 (HTTP)
  • → MySQL (localhost:3306)
  • → I-CSCF:3869
  • → S-CSCF:3870

Thank you!

[miaoski]

Here is a draft, but I still have to verify it against the actual PCAP.

Source code in https://github.com/miaoski/docker_open5gs/blob/master/network-topology.dot

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