Billion 8800NL R2: Difference between revisions

==Support for baby Jumbo frames (1508)==

This was a standard feature in the original BT supplied ECI and Huawei modems. This means that a PPP ethernet router which supports RFC 4638 can

run with an MTU of 1500.

We're not yet sure if the 7700NL supports and MTU of 1508, but we have asked (Feb 2017)

==PPP session ID cache bug 'packet accelerator'==

One problem we see with Broadcom based routers is that they have an

internal feature which is a 'packet accelerator' which causes problems when a PPPoE session finishes and a new one starts.

Ethernet frames 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.

Our understanding of this, having talked to Huawei 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 momentarily

resolves the problem - that action must trigger a cache flush in the

Broadcom chipset.

We're not yet sure if the 7700NL has this 'feature' enabled, but we have asked (Feb 2017)