I have a 877 modem (for reference, running c870-advipservicesk9-mz.124-15.T5.bin) which provides Internet access and routes between two VLANs.
I have found recently that when the Internet link flaps repeatedly (unrelated service provider issue) the modem appears to stop passing traffic altogether. I see this message popup on the console (repeatedly):
switch transmit queue full on ethernet0
I realise there's nothing the modem can do about the Internet flapping, but any advice on how it may be possible to keep the two VLANs communicating it would be appreciated (other than a power cycle, which DOES fix the issue).