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VMG1312-B10A: Bugs: Difference between revisions

VMG1312-B10A: Bugs (view source)

Revision as of 09:35, 18 May 2015

802 bytes added ,  18 May 2015
m
→‎PPP restart = broken VPNs AKA UDP Blackholing
m (AA-Andrew moved page VMG1312-Trial to VMG1312-Bugs)
We now have what looks to be the same fault on the ZyXELs - both on ADSL and VDSL.
 
When a PPPoE session finishes and a new one starts, ethernet frames
The fix in the Huawei modem was relating to an 'acceleration' setting in the modem. Disabling this feature fixed the fault. -this is not a user setting but built in to the firmware. -a new firmware wil be needed to fix this in the ZyXELs
containing IP packets with the same source and destination IP and port
combination that were used in the previous session are received with the
PPPoE Session-ID from the earlier session.
 
This affects long running sessions using protocols which use the same
For a longer description of the Huawei fault see:
source port for all communications. This includes IPsec and (in some
http://www.revk.uk/2013/11/bt-huawei-fttc-modem-bug-breaking-vpns.html
circumstances) SIP.
http://www.revk.uk/2013/11/bt-huawei-working-with-us.html
 
https://aastatus.net/1854
Our understanding of this, having talked to Huawei last year to get a
very similar bug fixed is that the problem is with the packet
accelerator feature in the Broadcom chipset. It is caching frame headers
including the PPPoE Session-ID, but not checking if the Session-ID is
the same when searching for the entry in the cache for subsequent
packets. Unplugging the ethernet cable from the VMG1312 momentarily
resolves the problem - that action must trigger a cache flush in the
Broadcom chipset.
 
Possible fixes would be to either not store the Session-ID in the packet
accelerator cache at all, or to check the Session-ID in addition to the
IP and ports when searching the cache. A workaround would be to disable
the packet accelerator.
 
====Date Reported====
====Updates====
2015-05-06 - Escalated with ZyXEL/Broadcom
2015-05-15 - ZyXEL staff came to AAISP offices and we demonstrated and discussed the problem
====Resolution====
None yet.
 
 
==QoS Issues==
AA-Andrew
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Retrieved from ‘http://support.aa.net.uk/Special:MobileDiff/9333’