buglwIP - A Lightweight TCP/IP stack - Bugs: bug #60502, PPP doesn't work with a cellular...

 
 

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bug #60502: PPP doesn't work with a cellular modem and TCP / IPCP doesn't handle No Options from DCE

Submitted by:  Barry Andrews <mrandini>
Submitted on:  Mon 03 May 2021 01:00:41 AM UTC  
 
Category:  PPP Severity:  3 - Normal
Item Group:  Faulty Behaviour Status:  None
Privacy:  Public Assigned to:  None
Open/Closed:  Open Planned Release:  None
lwIP version:  2.1.1

Mon 03 May 2021 04:28:35 AM UTC, comment #1: 

I don't know how to rename the bug report.  Should have been that PPP doesn't work with a cellular modem and TCP.

Barry Andrews <mrandini>
Mon 03 May 2021 01:00:41 AM UTC, original submission:  

Currently PPP to a cellular modem such as the Cinterion EC21 or Telit LE910 will not work for TCP as responses back from the server will be blocked because of incorrect PPP negotiation.

This is 100% repeatable.  I have attached a PPP hex dump for wireshark to show the difference in negotiation for the TIRTOS NDK PPP which works reliably (first session in the capture) and the LWIP negotiation which fails 100% of the time (Second negotiation).

In the IPCP I have noted that when a DCE has no options to negotiate the LWIP IPCP stack currently rejects its request to have no options. The TIRTOS stack ACKs this.

The TIROTS NDK works reliably with a TCP outgoing connection correctly getting a response back through the mode, the LWIP stack sends out the TCP packet and it is received by the server, but the response never comes back to the stack and hence a TCP connection cannot be established.

Barry Andrews <mrandini>

 

Attached Files
file #51364:  _PPP@hex@dump@1@-@Std@LWIP.txt added by mrandini (8KiB - text/plain - This is normal LWIP behaviour, previous had my attempt to fix handshake)
file #51363:  _PPP@hex@dump@1.txt added by mrandini (8KiB - text/plain - Wireshark format hex dump file, import with timestamp set to %M:%s., direction included and PPP protocol)

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -email is unavailable- added by goldsimon (Updated the item)
  • -email is unavailable- added by mrandini (Submitted the item)
  • -email is unavailable- added by mrandini
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    Follow 4 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2021-05-06 goldsimon SummaryIPCP doesn't handle No Options from DCE => PPP doesn't work with a cellular modem and TCP / IPCP doesn't handle No Options from DCE
    2021-05-03 mrandini Attached File- => Added _PPP@hex@dump@1@-@Std@LWIP.txt, #51364
    2021-05-03 mrandini Attached File- => Added _PPP@hex@dump@1.txt, #51363
        Carbon-Copy- => Added mrandini

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