Vodafone network rejections when switching cell towers
Aleksander Morgado
aleksander at aleksander.es
Fri Jul 1 09:25:23 UTC 2022
Hey,
>
> We are experiencing network rejections when our device switches from cell tower to cell tower.
>
> We have been in contact with our SIM provider, Vodafone, which says that this is due to us sending delete and create session requests too rapidly (within 40ms between requests).
>
> These are Vodafone's comments on the Wireshark trace (see attached) they have captured on their side:
> ===
> As can be observed in the shared traces, the new create session request was initiated after less than 40ms since the Delete Session.
> Also, it is visible that the session was not terminated internally, the Credit Control Terminate messages for the initial data session were sent after the Create session Request.
>
> Moreover, this SIM is having static IP allocation.
> Even if the IP is not assigned by the PGW, after a data session is closed, the IP assigned for that data session is set in quarantine for a specific period of time ( not configurable, it is calculated internally by the PGW).
>
> Based on the above, the reason why the session got rejected is due to the short period of time between Delete and Create.
> ===
>
> Is this a known problem? And is this something we could configure on the device/modem side?
>
> Thanks in advance for any insights on this matter!
>
> Some additional info...
> We use NetworkManager to setup the connection with our private APN.
> We are using MM 1.18.0 and libqmi 1.30.2 on Linux kernel 4.14.98
> We are using the SIM7100E from Simcom which is running firmware 4534B06SIM7100E
You need to bring this up to the modem manufacturer, there's nothing
in ModemManager that touches that logic.
--
Aleksander
https://aleksander.es
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