A lan connected by a satellite

[sarahr202]

Hi everyone.

Let say we have a lan as show below:

Lan1 10.10.10/8------ethernet switch1------ethernetswitch2---------lan2 10.10.10.0/8(  I marked them as lan1 and lan2 eventhough they are single lan)

Let say  these switcher (layer 2) are connected to each other via satellite rather than ethernet.

lan 10.10.10.0/8----- ethernet switch1-------satellite-----------ethernet switch2---lan 10.10.10.0/8

Let say host h1 located on lan1 sends a packet to host h2 on lan2.

1) what device is usually used between ethernet switch and satellite?  At what osi layer this device maps to?

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Let say host h1 located on lan1 sends a packet to host h2 on lan2.

How does this packet travel?  (  I mean h1 's ethernet frame arrives at sw1 ,how does sw1 process this packet after i has decided to forward it out of its port connected towards satellite?

thanks and have a nice  day

[mavespig · Accepted solution]

Hi Sarah,

If satellite connectivity is provided by an external device, connected to your switch via ethernet, then it is transparent, i.e. the switch will just forward packets as on a normal ethernet link.

From your switch point of view, that's just a cable.

On Cisco routers you can install a satellite network module (NM-1VSAT-GILAT). In that case the traffic is routed at L3, based on the routing table.

Some more info here:

http://www.cisco.com/en/US/prod/collateral/modules/ps2797/ps6989/product_data_sheet0900aecd804bbf6f.html

http://www.cisco.com/en/US/prod/collateral/modules/ps2797/ps6989/prod_qas0900aecd804bbf65.html

Hope this answers your question.

Cheers

Marco

[sarahr202]

HI Marco.

Thanks for your reply.

Lan1 10.10.10/8------ethernet switch1------ethernetswitch2---------lan2 10.10.10.0/8

Let say h1 wants to sends a frame to mac2 of host2 at lan2.

Ethernetsw1 mac table indicates entry as:

mac2   port2 (  which is connected to satellite's link via some device)

sw1 forwards that frame out of port2 to device which connects it to satellite i.e

  lan1 -----sw1---device1---uplink---satellite------down link---device2---sw2---lan2

When this frame arrives at device,  that device will forwards that frame to satellite link.

My question is this working at physical layer ? or datalink layer? or both?

Because  there some sort of medium access control .i tcould be tdma for example which will suggest the device is working at datalink layer.

In order for all whole process to remain transparent between sw1 and sw2 i.e  frame transmitted by h1 off lan1 to h2 off lan2, the frame must arrive at sw2 without any modification so sw2 can forward it to h2 after receiving it from device 2.

thanks and have a great day