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MRV with DECA verses hardwired ethernet?

Discussion in 'DIRECTV Connected Home' started by JRThiele, Apr 7, 2010.

  1. Avder

    Avder Hall Of Fame

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    Question about deca, am I right in assuming that all receivers connected through DECA are all in the same collision domain? Or does the SWM module act like a switch and each individual cable run is its own collision domain?
     
  2. harsh

    harsh Beware the Attack Basset

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    All devices must vie for the same bandwidth. The branches of the network are made with high bandwidth splitters. In MoCA and DECA, one node takes command and controls all of the cloud traffic. Some of the bandwidth is devoted to video traffic and the rest is left for handing UDP and "data" traffic.

    MoCA and DECA may have different traffic optimizations (MoCA can't ignore data traffic as that is currently its primary use), but the principle is the same.
     
  3. hdtvfan0001

    hdtvfan0001 Well-Known Member

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    As described in the First Look document...think of DECA as its own "sub-network"...focussed on keeping a pathway for media and audio streaming, and "cleaner" with significantly reduced potential for data collision (as opposed to some of the potential data conflict within regular network traffic).

    Since its designed to provided a special bandwidth for such streaming, MRV is optimized.
     
  4. usnret

    usnret Icon

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    Would the number of receivers on a DECA system slow it down (i.e. 2 receivers = fast, 6 receivers = slower)??
     
  5. Movieman

    Movieman Hall Of Fame

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    No one has reported that the amount of receivers causes any issues thus far.
     
  6. Doug Brott

    Doug Brott Lifetime Achiever DBSTalk Club

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    DECA/MoCA works differently than Ethernet, so there is no collision domain .. I think this is partly whey we've just been calling it a cloud. It also allows for priority packets which make trick play more responsive.

    There is a limit of 16 network devices in a DECA cloud. This device count includes the broadband DECA if needed.
     
  7. Doug Brott

    Doug Brott Lifetime Achiever DBSTalk Club

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    Yes and No .. @ The DECA level, this is probably a true statement as the cloud functions similarly to a switch .. The cloud is just wires, though whereas the switch is some sort of chip or board. Also, the protocol for delivery is different.

    However, at the box level it is IP. The DECA module or built-in DECA make the conversion from Layer 3 to Layer 2. Otherwise, functions within the box would have to understand MAC addresses.
     
  8. Avder

    Avder Hall Of Fame

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    So its somewhat like a token ring setup with one main box having total control of who has the token and that same box guiding layer-two frame prioritization and general traffic management.

    Hmm.
     
  9. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    I would disregard Harsh, since he doesn't have DirecTV or know that much about DECA.
    I have DECA and not sure "one DECA" is in command of the cloud. Each time a DECA comes on line, there is some activity as they negotiate "who's who" on the cloud.
     
  10. wavemaster

    wavemaster Godfather

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    Kind of funny that D* is starting to tout the "Connected Home" when in reality their approach is to dis-connect from everything else.

    We have what I would call a connected home in a practical sense (we still flush the toilets manually - lol).

    The 6 DVR's connect to their own Gb switch, there is also a connection to one Gb port on the NAS and one Gb port to the 24 port main switch. We can touch most of our media from most places. The Home Automation, DVR's, PC's, Internet, Media Centers, Game Consoles, BR players etc. all run inside the Ethernet "Home Network".

    If you are reading this D*, please don't ever abandon support for the actual "connected home" We sure don't need a bunch of splintered networks running on their own subnets. The aproach might make it easy for you, but for those of us that are actually trying to get to a "connected home" it is a PITA.
     
  11. JRThiele

    JRThiele New Member

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    Thanks for all the participation in this thread. I didn't realize I was asking such a pertinent question in the first place. I've learned a lot thanks to all your contributions.

    So I've done a little experimenting with my hardwired MRV solution with lagging MRV and reached a few conclusions:

    1. My lag during trickplay across MRV is more than others are reporting.
    2. The lag is the same when directly connected verses going through my Westell DSL router box.
    3. I've had my Blu Ray players plugged into the second HR23 Ethernet port and this is slowing things down.

    So, I guess I can add a cheap Ethernet switch at each DVR which will allow me to add the television and Blu Ray connections ( 3 total - DVR, TV, BD). This would require two switches in total - one in the living room and one in the bedroom. I assume these devices are powered and would include another brick to be plugged in somewhere too?

    Now, if I go the DECA route, do I still have the same problem with bringing both the TV and Blu Ray player into the network? In other words, will I still need to buy my own switches to include the TV and BD over the Deca connection somehow? Or, am I limited to only one extra connection via the second HR23 port?
     
  12. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    You would need to use/add the switch coming off the DECA at each location, to connect more than the receiver.
    Please stay away from using the second port on the DVR. It will only cause problems.
     
  13. harsh

    harsh Beware the Attack Basset

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    MoCA underpinning details are available aplenty on the Internet. MoCA's website offers several white papers that are very instructional and you don't need to be a DIRECTV subscriber to access, read or gain insight from them.

    There's even some mention of how the MoCA 1.1 standard brings DBS support by offering frequencies from 500MHz to 1.5GHz. It is enough to make one wonder if there's any difference between MoCA 1.1 and DECA.

    http://mocalliance.org/news/pr_100420_MoCA_adds_Mid_RF_Frequencies_to_MoCA_1.1.php
     
  14. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Show me a white paper on DECA and it might be worth reading.
    Short of that you're just guessing/assuming as you do with all of the DirecTV side of this forum.

    This does bring up the question:
    Why do you spend so much time here without the service?
    There is a dish side here.
    Are we just "the cool kids" here and you want to play? :nono:
     
  15. lugnutathome

    lugnutathome Hall Of Fame

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    I'm just handing out free advice (which is worth what you paid for it):grin: "Cheap Ethernet Switches" may be more of a headache than some not quite so cheap ones. I have had incredibly high failure rates with Linksys equipment, great experiences with mid range Netgear. YMMV.

    Yes these switches need power. And they would still be advisable even if you went the DECA route.

    From what I've been able to deduce...

    DECA gives you a special "hardwired seperate" network primarily for the DTV IP packet transfer environment that will also allow you to use it to connect the various DVRs in it's cloud for VOD internet access. This all interfaces from the cloud to your existing home network via a single port at the cloud's "base" (or it's head end) via a single port at a switch or router on your home network.

    One purpose of DECA is to provide a single end to end network for the DTV IP packet traffic isolated from all the other IP traffic on your regular home network. It uses its own "network cabling" (your DTV coax line already in place for Sat reception) and is completely supportable by Direct TV right up to the point where in interacts with your home network.

    For other network devices, PC, PS3, XBox, BlueRay player, network AV receiver, Sling Box, etc you will still need your own separate infrastructure to support them and DTV does not (nor can they) support the possible wired/wireless conglomerations consumers manage to implement

    Don "hope I didn't butcher the concepts here" Bolton

     
  16. harsh

    harsh Beware the Attack Basset

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    It seems likely that DECA is functionally identical to MoCA 1.1 outside of where it derives its power from.

    Do you know one way or the other?
     
  17. dennisj00

    dennisj00 Hall Of Fame

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    Think of DECA as simply a switch or more likely a 'hub' that uses coax that's already in place for the ethernet transport and has one location that is tied to your existing network.

    While the advantages are possibly exaggerated over a well done cat5 network, the simple advantage is that it can be installed and maintained by the D*tv installers. That's it.

    They can disconnect from your network and show you that MRV will work fine. The other network functions, mediashare, VOD are still your responsibility.

    It would be impossible for DirecTV to attempt to support MRV over the home-grown networks and literally millions of combinations of routers, switches, cabling, wireless adapters, powerline adapters that we've already seen can be marginal for MRV.

    Deca is the answer for networking required for MRV. That is not to say that your network will not work. Any better or any worse.
     
  18. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    "Close".
    I would say the whole cloud is more like one big switch, since the output of each DECA isn't the same as the ports on a Hub and are more like a switch.

    I can just see DirecTV saying "We'll charge you for MRV, but use your own network at your own risk". :lol:
    Can you? Yes.
    Do they want you to? I doubt it.
     
  19. dennisj00

    dennisj00 Hall Of Fame

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    I hope they do -- and that's been reported as the plan. I have no reason to rip out my multi-switch and network to substitute SWM and DECA. (or let an installer do it.)

    My MRV works perfectly - as do all of my HR2xes - along with all other network functions.
     
  20. harsh

    harsh Beware the Attack Basset

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    In a switch scenario there can be simultaneous uncontended bi-directional traffic between pairs of nodes. DECA's single "pipe" must carry all conversations and do so unidirectionally. While DECA has technology to avoid collisions, it is otherwise a very hub-like technology.
     

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