Linking via 10/100 for light duty?

[guyjwest]

I am busy now finishing up design work for my first multi-studio LW network. There are 2 studios that will each be based on elements. I have a small group of dedicated post production computers on another floor of the building that will be accessing the shared audio storage (2TB Snap Server Raid5).

I like to use the Cisco 2960G series including the 8 port version which makes a nice small studio switch. I have two questions to pose:

1) I have the main broadcast studio gear, its mix engine, plus GPIO and analog node, NTP and other equipment room shared items on a 2960G-24TC-L. I have the post production units on a 2960G-8TC-L downstairs. I am wondering if fiber would be the way to go for the link between the 8 and 24 port devices. Its going to be about 50m, give or take and no live streams, so perhaps Cat-6 would be fine.

2) For the 2nd studio I would like to use another of the 8 port ciscos, but after attaching its studio engine, I may need to use 10/100 port for the link to the rest of the network. I don't expect this to have high usage since the 2nd studio is usually doing program production and has very simple LW audio links to the rest of the network. I figure I should be able to get 8in/8out same as a node with no difficulty. Any comments on the risk?

Guy
Technical Services Director
Far East Broadcasting Co., USA

[AXIA_milos]

1) CAT6 cable limit is ~90m - 100m. That is the spec for the Category cable. So if the install is done well, we could expect your 50m run to be good. Best to test the cable that it meets the qualification. You could also do fiber, but the cost will be more.

2) You will likely saturate the link and if so you will have SYNC issues. Your better off getting an all Gig 8 port switch or a stand alone network with a node in the production space that is linked to your main network (this should provide you with 8 bi-directional streams that you can count on).

-m

[jp]

2) For the 2nd studio I would like to use another of the 8 port ciscos, but after attaching its studio engine, I may need to use 10/100 port for the link to the rest of the network. I don't expect this to have high usage since the 2nd studio is usually doing program production and has very simple LW audio links to the rest of the network. I figure I should be able to get 8in/8out same as a node with no difficulty. Any comments on the risk?

Not to contradict Milos, he is right about the potential for problems. But if you configure everything properly, you might be able to get away with it.

In our Bangkok bureau we have 4 very small studios and one larger studio with Axia gear, using a pair of Allied Telesyn switches, each with 2 GB ports. Since 2 of the GB ports are for cross connecting the switches that left us with 2 left for the studios.

We used 1 for the larger production studio's Engine and left the other open for future expansion. The 4 small studios have the following:

1 AES node
1 Analog node
1 Studio Engine
1 Element with GPIO/powersupply
1 mic pre, 2 mics
1 Minidisk
1 Telos One Hybrid
1 PC with Axia IP driver
1 analog aux line in for visiting equipment

So that's 6 sources and one mix minus, we only use PGM1, one analog out for headphones, one for speakers. We got away with using 100 MB ports for the 4 small studios' Studio Engines by disabling all unused sources on the nodes and all unused outputs (PGM2-4, auxes, etc) on the Element/Studio Engine.

They have been up now for 3 years without saturating the links or having any clock issues. YMMV

Regards -

jp

[AXIA_milos]

Yes John, some things are possible. It is possible to run for example an Engine on a 100base port, if the facility/tech knows how to use the equipment and understands the equipment. I recently came across a facility that was doing such a thing but only by mistake. This practice is highly discouraged. The reason for saying your Engine should be a 1000bps connection and not 100 (same applies for trunk connections) is that there is the possibility to push/pull more than a 100bps through an Engine or Trunk cable. This is why we say, must be a Gig connection. In cases where the port saturates, observers can believe the product is failing. I once forgot that I had connected an Engine to a 100bps port just so that I could do some initial setup - I did this because I knew it could be done. I forgot it was still connected to a 100bps port and when I had a 20 channel Element configured and began to populate all the channels... the Element began to behave not as expected. I almost began to tear the hair out of my head, but then I realized my mistake. The product was working as it should, the pipe wasn't allowing it to though.
An Engine can be very happy on a 100bps port, BUT ONLY IF THOSE RESPONSIBLE UNDERSTAND THE LIMITATION. The earlier case I gave about a facility... they were lucky in that the Elements were small, but they reported some odd behavior. When I arrived onsite - it was very clear what was going on. I trimmed the sources much as you have in your example and went a step further by disabling Backfeeds not in use. It is enough to get them going, but they plan to do some upgrades which will allow them to run under the "suggested" parameters and have carefree operations.