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  1. #1
    Join Date
    Jan 2007
    Location
    Northern California
    Posts
    122

    Question CCN Wireless Ethernet Bridge

    Has anyone used a wireless ethernet bridge on CCN equipment? Specifically the Carrier router configured as a bridge and connected to some UC's.
    The antenna manufacturer tells me they are working properly yet I continue to have transmission problems such as failed data packets. I cant imagine that I am sending too much data accross the antennas to the point that they bog down.
    BYW: I can see my devices, I just cant keep a good comm line with them. Could it be something that needs to be configured on the ccn side?

  2. #2
    Join Date
    Apr 2010
    Posts
    23
    Yep I’ve had some success with that, although I used commercial Ethernet to Wi-Fi bridges. I first tried to implement the Linksys (CISCSO) WET610N and had limited success with their daily operation plus their initial setup is a bugger. I’ve since switched to the Buffalo WLI-TX4-AG300N and have had much better luck with those; however I did get one DOA so I wonder about their QC. If you do go with either of the above IM me and I’ll send you my setup directions to say you some frustration and time.

    I fought with this same problem for a year in a half and even had our automation contractor bring in their “experts” to try and figure out the connection issue before I finally figured it out. Let me ask you a couple of questions:

    Does the nodes that your are have trouble communicating with- at a remote site, at any time does your network reach OSI layer 3 (any kind of data shaping going on, ie a VPN, SSL transition), do you have any bandwidth throttling going on, and/or even though your system can’t keep communications up can you still Telnet/SSH into the node when the system sees it as down?

    If you answered yes to any of the above I think I can tell you what your problem is.

    When a data packet reaches OSI layer 3 the MTU packet size is reduced splitting one packet into multiple smaller packets then if you’re crossing a VPN those packets are encrypted. Layer 3 is responsible for “Fragmentation and Reassembly” in the data transfer process. This process of fragmentation (MTU shaping) and reassembly (&/or encryption) takes additional time that your system is not accounting for plus you’re going to have a higher percentage of packet loss.

    On normal open layer 2 networks there is also packet loss but it’s not as great, so the amount of time allowed for all the hand shaking and packet verification (Checksum) is minimal. I’m talking in milliseconds here and I know it doesn’t seem like a lot but if two nodes are trying to communicate and their TTL (time to live), Checksum, and MTU size are not the same they will timeout and just quit talking with the assumption that the other node is dead.

    The easy fix is to use a subnet and IP range that is open and routable. It is for this reason you see credit card swipers and fax machines (Network using VOIP) transmit on open networks that don’t get compressed or encrypted.

    The not so easy (depending on your controls contractor) is to extend the TTL & Checksum values at the nodes and server.

    Hope this helped, - O
    You don't win a war by dying for your country. You win a war by making the other poor dumb bastard die for his!
    .

  3. #3
    Join Date
    Apr 2008
    Location
    Northeast
    Posts
    74
    Quote Originally Posted by ottoreload View Post
    Yep I’ve had some success with that, although I used commercial Ethernet to Wi-Fi bridges. I first tried to implement the Linksys (CISCSO) WET610N and had limited success with their daily operation plus their initial setup is a bugger. I’ve since switched to the Buffalo WLI-TX4-AG300N and have had much better luck with those; however I did get one DOA so I wonder about their QC. If you do go with either of the above IM me and I’ll send you my setup directions to say you some frustration and time.

    I fought with this same problem for a year in a half and even had our automation contractor bring in their “experts” to try and figure out the connection issue before I finally figured it out. Let me ask you a couple of questions:

    Does the nodes that your are have trouble communicating with- at a remote site, at any time does your network reach OSI layer 3 (any kind of data shaping going on, ie a VPN, SSL transition), do you have any bandwidth throttling going on, and/or even though your system can’t keep communications up can you still Telnet/SSH into the node when the system sees it as down?

    If you answered yes to any of the above I think I can tell you what your problem is.

    When a data packet reaches OSI layer 3 the MTU packet size is reduced splitting one packet into multiple smaller packets then if you’re crossing a VPN those packets are encrypted. Layer 3 is responsible for “Fragmentation and Reassembly” in the data transfer process. This process of fragmentation (MTU shaping) and reassembly (&/or encryption) takes additional time that your system is not accounting for plus you’re going to have a higher percentage of packet loss.

    On normal open layer 2 networks there is also packet loss but it’s not as great, so the amount of time allowed for all the hand shaking and packet verification (Checksum) is minimal. I’m talking in milliseconds here and I know it doesn’t seem like a lot but if two nodes are trying to communicate and their TTL (time to live), Checksum, and MTU size are not the same they will timeout and just quit talking with the assumption that the other node is dead.

    The easy fix is to use a subnet and IP range that is open and routable. It is for this reason you see credit card swipers and fax machines (Network using VOIP) transmit on open networks that don’t get compressed or encrypted.

    The not so easy (depending on your controls contractor) is to extend the TTL & Checksum values at the nodes and server.

    Hope this helped, - O
    Ottoreload,

    I'm working on a project where I have to run my own Ethernet network between building controllers.....one being in a remote building (approx 500 feet between buildings with no critical obstructions). It seems like you prefer the Buffalo device more than the Linksys. Have you run across any other good manufacturers?

    Thanks.

  4. #4
    Join Date
    Feb 2005
    Location
    Edmonton, AB Canada
    Posts
    603
    Quote Originally Posted by NightrainATC View Post
    Ottoreload,

    I'm working on a project where I have to run my own Ethernet network between building controllers.....one being in a remote building (approx 500 feet between buildings with no critical obstructions). It seems like you prefer the Buffalo device more than the Linksys. Have you run across any other good manufacturers?

    Thanks.
    Good day NightrainATC,

    Just a few comments... If you are looking to use the wireless link for building control data (i.e. you cannot tolerate unreliable operation), then I would highly suggest you use an industrial designed Wireless to Ethernet solution. Consumer Wifi's and even higher end consumer Wifi's just do not have the output power or antenna design to ensure consistent and reliable operation... especially under nasty weather conditions (i.e. snow, rain, etc). The customers I have worked with have tried/tested all of the lower end stuff (i.e. less than $1000) and found them to be not be up to the task. If I remember correctly a suitable and high reliable system was quite pricey ($5K+), but it was needed given their site and the distances involved.

    If you are still unsure, then try the devices you mentioned and test, test, and test to ensure that the system works to your satisfaction.

    Cheers,

    Sam

  5. #5

    Wireless Ethernet

    May want to check www.aic-wireless.com. AIC900-E is a very powerful Wireless Ethernet Bridge (Operates in 900 Mhz and 2.4 GHz ranges). Very reliable for most Building Automation and Metering applications. Ranges exceed several miles in some cases with proper antenna placement.

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