modem exchange issue

[ok1rn]

Hi everybody
I have interesting issue. After several years of usage RRC-1258II, i upgraded my home conectivity from ADSL to VDSL. Unfortunately i'm now not able to connect to the remote. I bring the modem back to the operator, but it seems that with modem everything is ok and problem is in RRC.
As the opertator technician dicvovered, RRC connected to the new modem turns over the sequence of the session opening packets and the server side simply rejects the connection than. Technician tested everything with both, previous and new modem on the same line, with the same RRC, and result is that packets order with old and new modem is reversed. Traces were done on local LAN interface. Is there any reason why RRC behaves so? Any idea how to fix? I tried the latest firmware, but no change.

I have trace logs available, so i can send them by e-mail for deeper investigation if reasonable.

tnx Petr

[sm2o]

If you change modem and it stops working you must understand that the problem is in the modem or the network not in the RRC.
Try to change port numbers and check that the modem/router do not have anything called SIP ALG activated.

73 de mike

[dj0qn]

Hi Petr,

Sorry to hear about your problem. To be honest, it doesn't make sense to me. There  should
be no difference whether you use ADSL or VDSL. I also switched to VDSL 50/10 three years ago
with no difference.

You only refer to a modem in your explanation. Do you have a separate router to the modem, or
are you referring to a router/modem combination? If you had a separate modem and router, then
switching to VDSL should make no difference. If you changed a combination router/modem, such
as to the Fritz!Box 7390, then of course you need to reenter all of your port forwards again.

Maybe you can clarify this point.

73,
Mitch DJ0QN / K7DX

[sm2o]

Sorry about my tone, but sometimes I get tired when people think the RRC is the problem even if it obvious that something else is the problem. Like if the phone line is cut of by a falling tree.

The VDSL can be a totaly different service even if it uses the same copper wire, so there can be ports which is blocked even if they where not before. And like Mitch says probably the modem is new and if it includes the router there might be settings which are different.

I hope you solve it.

73 de mike

[ok1rn]

Dear Mikael, Mitch,
Your answers sounds logically, but you probably miss the point. Behavior what i was describing, is not seen on WAN interface behind the modem, but on LAN what means this is going from the RRC, yet before modem(router) got chance for any modification of the traffic.

To Mitch - correct, the modem is combined with router, namely it’s Zyxel P-870HN-53b. Of course, first what i set was NAT/PAT, but no sucess neither when trying DMZ. I already switch all enhanced functionalities off, even including firewall, but still without any change. Believe me, i has beeen playing with this setup more than one month wihout success.

As you can see on enclosed printscreens, RRC sending SIP INFO later than RTP STREAM, whac causes that remote answers ICMP destination unreachable. Do you have any explanation, why RRC is sending packets in such order?

[dj0qn]

Hi Petr,

You have an interesting problem, but it still doesn't make any sense. Why would the RRC all of
a sudden, without any change whatsoever, begin to generate packets "backwards"? I can not
believe that it is a problem with the RRC and for sure must be a router issue. I have seen routers
do strange things like you are showing on your screen shot before, I just can't remember right
now how we solved it.

My suggestion is to borrow another type of router from someone and see if the problem
persists. Then at least you can confirm or eliminate the router or RRC as the source of the problem.
I have had good luck on VDSL with the Fritz!Box 7390, although I do find it too "dumbed down" for
my taste.

73,
Mitch DJ0QN / K7DX

[sm2o]

I fully agree with Mitch. First check that the Router has the latest available firmware. If so replace the router. We have so far not heard about any router which does not work with the RRCs so the problem is the router firmware or the settings, there is nothing we can do about it.

73 de mike

[ok1rn]

Hi guys,
try another modem, thats what im going to do anyway, because with this one i already try everyhing. I will let you know here of the result after my holiday

rgds Petr