Are satellites layer 2 devices?

Node Man

Hi Everyone,
Besides orbiting the planet and having solar panels, are communications satellites considered layer3 or 2 devices? Do they do 'smart' routing?


Just wondering.

networkjutsu

I used to work for a Fortune 50 company that use VSATs as their backup for their sites - about 8500++ locations. As far as their setup goes, the only routing supported on the VSAT terminals (Hughes HN7700) is RIP - forgot if it was version 1 or 2.

chrisone

major ouch on any routing misconfigurations there lol

MSP-IT

I would think that it would really be dependent on the type of satellite. I'm sure there are satellites with both layer 2/3 built in.

mikeybikes

chrisone wrote: »

major ouch on any routing misconfigurations there lol

Gonna need a long console cable.

gorebrush

networkjutsu wrote: »

I used to work for a Fortune 50 company that use VSATs as their backup for their sites - about 8500++ locations. As far as their setup goes, the only routing supported on the VSAT terminals (Hughes HN7700) is RIP - forgot if it was version 1 or 2.

Surely then, this would imply they are L3 devices.

jibbajabba

mikeybikes wrote: »

Gonna need a long console cable.

reload in 10

networker050184

The satellite link itself would be considered the physical layer. Whether the provider attaches a router on the end for your hand off is pretty irrelevant. That would be like saying Ethernet is layer 3 because there is a router on the end you can exchange routes with.

emerald_octane

networker050184 wrote: »

The satellite link itself would be considered the physical layer. Whether the provider attaches a router on the end for your hand off is pretty irrelevant. That would be like saying Ethernet is layer 3 because there is a router on the end you can exchange routes with.

This.

OP, Cisco has a Satellite module available for their routing platforms. The documentation should answer alot of your questions regarding the how.

Source: Docuementation Above.

networkjutsu

gorebrush wrote: »

Surely then, this would imply they are L3 devices.

IIRC, not all VSAT terminals can do routing. Before they upgraded to HN7700, they were using Hughes PES (Personal Earth Station) and they didn't do routing. Also, there was another external devices that connects to the PES, which I forgot what it was called. With the HN7700, two devices were combined into one and the latency was reduced from 1200-1800ms to 600-800ms.

EDIT: Even the old PES did RIP. Also, the extra unit that I was talking about was for different purpose. It has been a while so forgot most of it.

EDIT2: First statement was correct. PES connects to another device which does the routing. The PES itself didn't do the routing. Though, I believe PES 5000 does support routing but if my memory serves me right we still use the external device to do the routing.

malikhan292

As someone said above, question of L2/L3 is irrelevant. Satellite or Radio links are linked with Phy/Mac layer of the OSI. Satellites in the orbit receives the ground signal and relay back to the desired region.

networkjutsu

Sorry to beat this topic to death but I just remembered about Cisco's IRIS (Internet Routing In Space). Most of the routing are done on the ground so with IRIS this would eliminate the double hop nature of satellite communications. Current setup is like this: Site A sends traffic to the 'bird' then sends to the hub then sends the traffic again to the 'bird' then eventually reaches Site B. With IRIS, this should eliminate the hub and hopefully enable acceptable real time traffic.