FYI Networking

Stream Songs From Phone to Computer

There are many apps to stream from computer to phone (AirStream: Stream PC over Air or SoundWire) but I want to listen to a podcast or music using my Android phone but listening on my computer or  headset.  It’s a good thing you can  play the song wirelessly using Bluetooth on both the devices.

  1. Install Microsoft Windows Mobile Device Center.
  2. Turn on Bluetooth on the computer and the phone then  each of them visible.
  3. Right-click on the Bluetooth icon in the Windows system tray and select the option Add a device
  4. Pair your phone and your computer with each other.
  5. Right-click on the Bluetooth   icon in the system tray again but now select Show Bluetooth Devices.
  6. Right-click on your paired phone and click on the Bluetooth Operations.
    1. (If A2DP support is available on the phone, it will show an option to Play Music under Audio and Video operation.)
  7. Click on the link to activate.
  8. You should now have a player control will appear on your taskbar (If not, try and right-click on the taskbar and select Bluetooth Remote Control under the Toolbars)

If you run into a problem, check this out.

Networking Telecommunications


A Data Service Unit/Channel Service Unit (DSU/CSU) WAN Interface Card ( WIC) these days is usually a blade on a router.  In the past, these were separate.  The CSU originated at AT&T as an interface to their non-switched digital data system. The DSU provides an interface to the data terminal equipment (DTE) using a standard (EIA/CCITT) interface. It also provides testing capabilities.  They evolved from standalone hardware, to shelf type systems and are now just a blade or Wan Interfacde Card (WIC) in a router.

Internal CSU/DSU WIC
Internal CSU/DSU WIC


External CSU/DSU Universal Shelf
External CSU/DSU Universal Shelf


External CSU/DSU
External CSU/DSU


The functions of the LEDs

WIC-1DSU-56K4 Front Panel DSU/CSU WIC to a 56/64-kbps Services Wall Jack RJ48S

LED Description
TD Data is being transmitted to the DTE interface.
RD Data is being received from the DTE interface.
LP Internal DSU/CSU is in loopback mode.
AL One of these alarm conditions is present: no receive signal, loss of frame signal from the remote station, or out of service signal from the remote station. This LED is off during normal operation.
CD Internal DSU/CSU in the WIC is communicating with another DSU/CSU. This LED is on during normal operation
WIC-1DSU-T1 Front Panel
Push this button to place the WIC into loopback mode. The service provider can send a signal to test the connection from your site to the central office switch. Push this button again to turn off loopback mode.

DSU/CSU WIC to a 56/64-kbps Services Wall Jack RJ48S


There are many manufactures, each with their own ideas of abbreviations so TD, TX, or TXD all mean you’re transmitting data. You may not have every LED but in general…


Power, PWR Power
ERR, ER Error indicator
AL, ALARM Critical alarm indicator
Loop, LP Diagnostic loopback indicator
SYNC, RS DTE sync indicator (Receive signa from telco)
 TD, TX, or TXD Transmit data
 RD, RX, or RXD Receive data
 CTS Clear to send (per flow control)
 CLOS Carrier loss of signal
 RLOS Receiver loss of signal

What you could see

Scenario Power Err Alarm Loop Sync TD RD CTS CLOS RLOS Description
1 flash flash Normal – up and passing traffic
2 Loopback mode detected from telco or configured in CPE
3 flash flash flash Circuit is experiencing errors, but still passing traffic.
4 CSU detects a total disconnect. Circuit disconnected/no cable.
5 Carrier loss of signal. Possible timing, switch misconfiguration, or circuit degradation
6 Receiver loss of signal. Possible timing, switch misconfiguration
11 No Power

See Also:

DataSMART-558 DataSMART_558 DataSmart_500_Series

FYI Networking

How Computers Work… (totally rad computers that is)

Networking Telecommunications

Traffic Shaping

Traffic shaping (also known as “packet shaping”) is a computer network traffic management technique which delays some or all datagrams to bring them into compliance with a desired traffic profile. Traffic shaping is a form of rate limiting.

So… Let’s say you’re a business that processes credit cards.  You have 15 stores and 1 corporate headquarters that has your computer network.  They 15 stores only need a little bandwidth to send the transactions to HQ but the HQ needs more bandwidth to accept the data from all of the 15 stores.  What you have is a mismatch in bandwidth (or CIR, Committed Information Rate.)  The stores would only need a 56K DS0 (56,000 bits per second) circuit but the HQ would need a full T1 (DS1) running at 1.544 megabits per second to handle all the traffic coming from and going to the stores.

So the problem is, the HQ is a fire hose and the stores are a garden hose… You can’t spray a fire-hose into a garden-hose and not expect some water is going splash out.  In data, that water would be drops or lost packets.

Networks are often asymmetrical, that is, the access rate at one site may differ from the access rate at another. In such cases, it may be necessary to configure the faster rate to shape to the access rate of the slower rate.

To limit bandwidth, you can shape or you can police.

Traffic policing propagates bursts. When the traffic rate reaches the configured maximum rate, excess traffic is dropped (or remarked). The result is an output rate that appears as a saw-tooth with crests and troughs. In contrast to policing, traffic shaping retains excess packets in a queue and then schedules the excess for later transmission over increments of time. The result of traffic shaping is a smoothed packet output rate.


Policing Versus Shaping


Shaping implies the existence of a queue and of sufficient memory to buffer delayed packets, while policing does not. Queueing is an outbound concept; packets going out an interface get queued and can be shaped. Only policing can be applied to inbound traffic on an interface. Ensure that you have sufficient memory when enabling shaping. In addition, shaping requires a scheduling function for later transmission of any delayed packets. This scheduling function allows you to organize the shaping queue into different queues. Examples of scheduling functions are Class Based Weighted Fair Queuing (CBWFQ) and Low Latency Queuing (LLQ).

Simply stated, both shaping and policing use the token bucket metaphor. A token bucket itself has no discard or priority policy. Let’s look at how the token bucket metaphor works:

  • Tokens are put into the bucket at a certain rate.
  • Each token is permission for the source to send a certain number of bits into the network.
  • To send a packet, the traffic regulator must be able to remove from the bucket a number of tokens equal in representation to the packet size.
  • If not enough tokens are in the bucket to send a packet, the packet either waits until the bucket has enough tokens (in the case of a shaper) or the packet is discarded or marked down (in the case of a policer).
  • The bucket itself has a specified capacity. If the bucket fills to capacity, newly arriving tokens are discarded and are not available to future packets. Thus, at any time, the largest burst a source can send into the network is roughly proportional to the size of the bucket. A token bucket permits burstiness, but bounds it.

Use the police command to specify that a class of traffic should have a maximum rate imposed on it, and if that rate is exceeded, an immediate action must be taken. In other words, with the police command, it is not an option to buffer the packet and later send it out, as is the case for the shape command.

 This example shows the configuration of two traffic-shaped interfaces on a router. Ethernet interface 0 is configured to limit User Datagram Protocol (UDP) traffic to 1 Mbps. Ethernet interface 1 is configured to limit all output to 5 Mbps.

access-list 101 permit udp any any
interface Ethernet0
traffic-shape group 101 1000000 125000 125000
interface Ethernet1
traffic-shape rate 5000000 625000 625000