Networking 101 – Handy to know before you jump into this hobby

Thanks to vxWorks

Here’s a basic fundamental guide on networking 101 for these newbies just now getting into this hobby… This is simply to just get them to learn how exactly networks work so they have all of the necessary network fundamentals down pat which should help em out and not have so much n00b posts after they’ve gone thur this…

Home networks generally have a LAN Address which isn’t accessible via the Internet….Unless you’ve already opened a port for it on the router or upnp does the port managing…
The IP range would be something like 192.168.x.x Anything on this range is in your network and cannot be accessed via iNET unless you open a port and forward it to your LAN IP….
Anytime someone says Change your CPE / NIC mac they mean change either the Router Mac or PC mac whichever is connected to the modem… Most of the time it’s the router mac that needs changin’ so go on and login to your router and change the mac by using the “Clone Mac” option / settings which is basically in most routers these days…. If your directly attached to the Modem and need to change your NIC Mac then just grab macmakeup which should do the job just great.

Anything past the Router / Modem is a WAN network which is the Wide Area Network = WWW = Inter webs!!!
Each modem only pulls 1 WAN/Public IP… To find your IP just go to http://whatismyip.com

Underdeath the WAN IP / WWW IP is a series of HFC Ranges…. 10.x.x.x etc…. This is generally a private setup / range for ISPs to use only… Not really for public use…But this range is like a goldmine for folks who can successfully snmp scan etc… Since they can reap dozens of equipment / device info off this range typcially… But in some cases where you cannot scan since filters are in place or snmp scanning is simply blocked you can try snmp scanning your WAN IP instead… This works good for me on some ISPs like RoadRunner etc…

Each ISP has a different setup… Not all have the same setup…. Meaning you can’t just grab any config file from any isp and upload it to your modem and expect it to work…

Putty is the best Telnet app since you can easily set it up to log all output from your telnet session… Just keep in mind you need to login as soon as the modem powers up so you can capture the reading of the config your ISP is stuffing down the modem.. After this you should be able to find your community string in the log. This is also the best method of seeking assistance if you are having issues with getting online w/ your modem… A output of a telnet log will tell all what’s wrong… A log is the only way you can troubleshoot your issue if any accurately.

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T1,T2,T3, & T4 Timeouts Descriptions

Thanks to baranek110 for the tutorial.

T1 ( No UCD’s received )

Explanation: The cable modem has not received any periodic Upstream Channel Descriptor (UCD) messages from the CMTS within the timeout period. This error message is DOCSIS event message is U01.0, Upstream Channel Descriptor.

T2 ( No Maintenance Broadcasts for Ranging opportunities received )

Explanation: The cable modem did not receive a broadcast maintenance opportunity in which to transmit a Ranging Request (RNG-REQ) within the T2 timeout period (approximately 10 seconds). The cable modem is resetting its cable interface and restarting the registration process. This error message is DOCSIS event message is R01.0, Ranging Request.

T3 ( Ranging Request Retries Exhausted )

Explanation: The cable modem has sent 16 Ranging Request (RNG-REQ) messages without receiving a Ranging Response (RNG-RSP) message in reply from the CMTS. The cable modem is therefore resetting its cable interface and restarting the registration process. This typically is caused by noise on the upstream that causes the loss of MAC-layer messages. Noise could also raise the signal-to-noise ratio (SNR) on the upstream to a point where the cable modem’s power level is insufficient to transmit any messages. If the cable modem cannot raise its upstream transmit power level to a level that allows successful communication within the maximum timeout period, it resets its cable interface and restarts the registration process. This error message is DOCSIS event message is R03.0, Ranging Request.

T4 ( Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received )

Explanation: The cable modem did not received a station maintenance opportunity in which to transmit a Ranging Request (RNG-REQ) message within the T4 timeout period (30 to 35 seconds). The cable modem is resetting its cable interface and restarting the registration process. Typically, this indicates an occasional, temporary loss of service, but if the problem persists, check for possible service outages or maintenance activity on this particular headend system. This error message is DOCSIS event message is R04.0, Ranging Request.

T6 ( Cable Interface Reset )

Explanation: The cable modem has sent 3 Registration Requests (REG-REQ) to the CMTS without receiving a Registration Response (REG-RSP) within the T6 timeout period (3 seconds). The cable modem is therefore resetting its cable interface and restarting the registration process

This problem can also occur if the DOCSIS configuration file is corrupt, or if it contains a large number of vendor-specific information fields (VSIF). If the configuration file contains a large amount of VSIF information, the cable modem might generate a Registration Request (REG-REQ) that exceeds the maximum size of DOCSIS MAC-layer management messages (1514 bytes plus the header). The CMTS considers this an invalid MAC-layer management message and drops it, without replying.


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Upgrade Firmware Via Telnet

Here is just another way to update your firmware, it only requires a tftp server and you must have a shell firmware installed.
1.change your ip to 192.168.100.10/255.255.255.0

2.start up your tftp server and make sure it is hosting the firmware.hex.bin to be flash

3.telnet your modem and type this cmd: dlfile
you will be prompted to enter the tftp ip, which will be 192.168.100.10 ,then prompted again for the firmware name, which will be the exact name firmware.hex.bin that you are hosting on your tftp server. Now you will see the some code being executed and see the tftp transfer happen, do not interupt this process!! the modem is writing the firmware to flash and will reset/reboot itself..your new firmware is now installed.

update:
Usually this command will work properly.
dload -f -i 1 192.168.100.10 firmware.bin

CODE

COMMAND: dload

USAGE: dload [-i Number] [-l] [-f] IpAddress Filename{255}

DESCRIPTION:

Downloads the specified s/w image from the TFTP server and stores it in the image slot specified. The image must be valid for the platform, and must not contain any security, encryption, or digital signatures. It must be a simple image file with only the normal ProgramStore compression header. Parameters:
-i — Specifies the image slot to store the image to.
-l — Allows a large image to be stored, spanning images 1 and 2, if
allowed by the flash driver configuration.
-f — Forces the given image to be accepted, as long as the CRCs are
valid.

Note that you must always specify the TFTP server address and filename; unlike the dload command in the Docsis directory, this command doesn’t make use of any Docsis-specific nonvol settings, so it can’t remember the last values used.

EXAMPLES:

dload 11.24.4.3 vxram_sto.bin — Stores the image to the default image slot.

dload -i 1 11.24.4.3 vxram_sto.bin — Store the image to slot 1.
cd /doc
dload

COMMAND: dload
USAGE: dload [-i Number] [-s] [-l] [-f] [IpAddress] [Filename{127}]

DESCRIPTION:
Causes the CM DOCSIS Control thread to download and store the specified image file via TFTP from the specified TFTP Server IP address. When the download is completed, the next reboot will run this image. If you omit the filename and/or IP address parameters, then we will use the ones stored in non-vol settings.

The -i parameter specifies the image number to be overwritten
(number of images depends on the platform). If omitted then the default image for the platform will be used. If present, the -s causes Secure Download to be used. The -l flag selects image1 as the target and allows a large image to be loaded, if allowed by the flash driver. The -f flag forces the image to be loaded even if the signature or compression types are not valid for the platform.

EXAMPLES:
dload 11.24.4.3 ram_sto.bin — TFTPs ram_sto.bin from the server.
dload -i1 11.24.4.3 ram_sto.bin — Same, but downloads to image1.
dload — Uses the file/server from non-vol settings.
dload -s 11.24.4.3 ram_sto.bin — Secure download.
dload -l 11.24.4.3 ram_sto.bin — Download large image to image1.
dload -f 11.24.4.3 ram3360_sto.bin — Loads a 3360 image onto a 3345 modem.

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