Problem with satellite link

Unanswered Question
Feb 13th, 2009

I have the following problem:

I have connected my central router with remote router over satellite link.

I have incompressible situation. I lost comunication in remote router with ip phone and with server 1.1.1.21 port tcp 7778.

But in that moment, i can make ping to remote router from central router, and vice versa. When i Reboot the satelital modem and remote router, ip phone and aplication with port tcp 7778 return.

Who have experience with satelital link?

why i can make ping and can't connect ip phone and to comunicate in port tcp 7778?

I have this problem too.
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Paolo Bevilacqua Fri, 02/13/2009 - 14:28

There is really no obvious explanation. Satellite circuits are supposed to be always available and you may want to seek help from the provider.

griffith2009 Sat, 02/14/2009 - 12:57

Do i need to shape to 128k in the interface interface FastEthernet0/1 of the router remote ?

The shaping have some benefit in this case?

The connection is so:

router remote (FE) --(100/full)-- (FE) modem satellite --(128k)-- modem satellite (FE) --100/full-- (FE) router provider satellite (Se)--(128k)--(SE) central router

FE = Fastethernet 100/full

SE = Serial - Frame relay (128k)

Paolo Bevilacqua Sat, 02/14/2009 - 13:01

Hi, usually the shaping is done so that you can prioritize voice traffic. Without shaping, you cannot do QoS on Fe.

griffith2009 Sat, 02/14/2009 - 13:38

According to your analysis i need to apply shaping in fe0/1.

I can do that with next command in remote router or i need apply other configuration?

-----------------------

policy-map C

class class-default

shape average 1280000

service-policy Q

---------------------------

interface FastEthernet0/1

service-policy output C

Don't care that i keep speed 100, duplex full?

What is happening right now that i do not have applied shapping??

Thanks.

Paolo Bevilacqua Sat, 02/14/2009 - 13:49

Hi, as mentioned above, shaping is only necessary when doing a priority QoS for voice, your example above is incomplete, Q should the a policy-map for class voice.

Nothing happens if you don't shape. The satellite modem has some buffering and then you're limited by the speed of the uplink.

griffith2009 Sat, 02/14/2009 - 17:15

I was reading a little about satelites and traffic shapping.

Apparently the satellite modem have a limit of TCP connections, which affects the buffer of the modem, if i can do traffic control of the outgoing class default of the interface fastethernet through traffic shapping, possibly

I can avoid that collapsing the number of tcp connections of the modem and the buffer.

Also could avoid the possible congestion that can generate this "class default" in the interface serial of central router.

Possibly excess traffic generated by the class default this causing the strange behavior that i have in the network.

What do you think about this?

Paolo Bevilacqua Sun, 02/15/2009 - 02:37

Hi,

Do you know what the limit is? You might find that it could be some thousands, so unlikely to be reached.

Also, you cannot never congest the serial interface in the hub, because if your traffic contract is 128 kbps, the satellite modem will never transmit more than that.

Beside that,no traffic condition or congestion should cause the circuit to go down requiring the modem to be reset, that is not acceptable and the provider should take care of that.

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