1 Topic by zhangye

  • zhangye
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Topic: About Active Bunldes in VLANS

"A second limitation is encountered in the capacity of the conductor and its ability to represent permission for many active transmitters in a maximum length 1500 byte beat packet. The answer to this depends on the number of bundles each device is transmitting. If each device is transmitting one bundle, there may be up to 184 transmitters active simultaneously, producing a total of 184 active bundles. If each device is transmitting a full 4 bundles, only 105 transmitters could be active, though theses would be producing a total of 421 active bundles. The eventual introduction of private bundles will erase this limitation."

The above is from "How many actively transmitting devices can exist on a CobraNet network at a time?" by www.Cobranet.info

I understand the Nion full bundles have 16  transmittings, CAB has full bundles have 4 transmittings.

I have the following questions：
1.If every  transmittings of nion used Unicast Bundle, how many active bundles in one VLAN?

2. If every  transmittings of nion used multi-Unicast Bundle of 4 mode, how many active bundles in one VLAN?


Our system have 12 nions,128 Ci amps,12 CABs,96 nWall has 2 channel with one bundle.

Does our system need VLAN？

Last edited by zhangye (2012-11-12 23:17:09)

2 Reply by Fergy

  • Fergy
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Re: About Active Bunldes in VLANS

This is a HUGE system!
I count transmitter a little differently, but it has served me well.  First, I consider a limit of 42 to 46 transmitter to be on the high side of what a CM-1 can do, and that if CM-1 is also doing a lot of controlling (talking about the 12 CABs here), then fewer transmitters can be managed.

But I consider a single NION to be a transmitter, so that would be starting with 12 transmitters.  But each nWall would also be a transmitter, so that is 96.  A CAB 8i or 16i would be a transmitter, but not a 16o.  A CAB 4n would only be a transmitter when an input card is installed.

Though you have not defined your CABs, I will count them as transmitters.  So 12 NION, 12 CABs, and 96 nWalls would give you 120 transmitters, which means I would allow for at least 4 VLANs, but 5 would make me feel more comfortable, even if the CABs are receivers.

Another suggestion is to watch your backbone usage.  Because you also don't define the Ci amps, (30 x 4 or 20 x 8), I will take the worse case, 128 Ci 20 x 8 amps would be 1024 channels of CobraNet.  Something to keep in mind is that 256 channels would saturate a gigabit Ethernet link, which would case the link to have lots of CN errors and so fail.

You may have already taken into consideration all of the backbone links, but there was a project of a few years back that that we thought was going to go well, until we started to consider how spanning tree could change the backbone flow.  The installer then found a couple links that could become saturated if the fiber backbone failed in certain ways.  Some additional links were added to make sure this would not be a problem.

Let us know how the install goes,

Fergy

Make it intuitive, never leave them guessing.

3 Reply by zhangye

  • zhangye
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Re: About Active Bunldes in VLANS

Fergy,thank you for reply .
I read your reply, I have a few questions。
1. You consider a limit of 42 to 46 transmitter to be on the high side of what a CM-1 can do, how did you   get 42 to 46 transmiiter?
2.Befor your reply ,I understand the transmiiter is bunndle,such as one nion have 16 TX ,so nion lagest transmiters is 16. Now ,I think I'm wrong.But

3.We have one PCR,and we have 24 SCR, The network topology is a star， backbone links is  gigabit Ethernet link. PCR installed NION, 16 of 24 SCR installed switch that from  the field of installed nwall  link. 8 of 24SCR installed Ci20x8. Our system for airport paging. We didn't have 1024 zones , We have 312 zones and 523 Speaker circuit . Most of CI20x8 has bridged.
I Plan to do this :
Every nwall have one bundle, CAB have one bundle , Total input device bundle is 108 .Every nion used max rx that will need 8 nions for recive.
Nion tx for amp, I plan use multi-Unicast Bundle and Unicast Bundle . Therefore  some of amp that One Bundle to maximum  amp is 4.some of amp that one bundle to one amp. Every have 4CH.
You help me look at the following network flow calculations are correct：
one Unicast  bundle one CH is 1 Mb at 48k 16bit.
one multi-Unicast  bundle  one CH at maximum 4 mode is 4Mb  at 48k 16 bit.

Thanks.