Wondering if anyone has experienced issues with the Bell Sagemcom F@st 2864
modem/router that's being shipped with newer Fibe services? Ran into an
issue yesterday that I can't wrap my head around.

Configuration looked like this:

Bell Modem -> Switch -> Phones & Asterisk

DHCP leases came from the Bell modem. Phones were configured to use
Asterisk for primary DNS, Bell Modem as their secondary DNS. Phones are
Cisco SPA 303s.

On a SIP reload, all phones would register properly to the local Asterisk
instance. Calls could be made between extensions. After about 30 seconds,
all peers showed a status of "UNREACHABLE". Obviously at that point, calls
no longer worked. Take the Bell Modem out of the equation and put in
something else to hand out leases, everything works just fine. The
configuration is identical on the other router (same DNS forwarders, IP
scheme, etc.).

Traffic captures on Asterisk made it appear as though traffic was just
disappearing. Initially we'd see the SIP registrations, options packets
went back and forth, etc. After the 30 second period, we would send
challenges in response to re-registrations, but nothing came back. However,
Asterisk can still ping the phones at this point.

Turned on remote syslogging for the phones and rebooted them a couple of
times. The phones simply showed "SIP:RegFailed;Retry in 30s". The logs show
that the IP the phones are connecting to is the correct, internal IP
address of the Asterisk server. So from what I can see, it looks like
Asterisk says it's sending the challenge, and the phones say they're
sending responses. Both sides, despite being able to route packets to one
another, state that the other side did not respond.

As with most ISP gateways, the fix was to put a different router in front
of the modem and put the modem into bridge mode - but I'm stumped as to
what could have caused LOCAL traffic to get dropped when the Sagemcom
gateway is in place. Why is traffic that should only ever have to cross the
switch, and not the gateway, getting redirected or eaten by the gateway?
What mechanism is the gateway using to do this?

Any thoughts appreciated!

Thanks,
Alex



-- 
Alex Robar
[email protected]

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