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VOIP codec choice

When use VOIP service with a VOIP adapter, you have to choose the codec.
The codec is very important. Unsuitable codec will make your call intermittently.
Codecs are settings used to fine-tune the audio compression of your VoIP devices.
Different codec needs different bandwidth.
The following protocol header assumptions are used for the calculations:
40 bytes for IP (20 bytes) / User Datagram Protocol (UDP) (8 bytes) / Real-Time Transport Protocol (RTP) (12 bytes) headers.
Compressed Real-Time Protocol (cRTP) reduces the IP/UDP/RTP headers to 2or 4bytes (cRTP is not available over Ethernet).
6 bytes for Multilink Point-to-Point Protocol (MP) or Frame Relay Forum (FRF).12 Layer 2 (L2) header.
1 byte for the end-of-frame flag on MP and Frame Relay frames.
18 bytes for Ethernet L2 headers, including 4 bytes of Frame Check Sequence (FCS) or Cyclic Redundancy Check (CRC).
So the most used often protocol/codec are listed below.
Codec Name – Bandwidth Ethernet (Kbps)
G.711 (64 Kbps) – 87.2 Kbps
G.729 (8 Kbps) – 31.2 Kbps
G.726 (32 Kbps) – 55.2 Kbps
G.728 (16 Kbps) – 31.5 Kbps
So, if you use two computer and one game palyer, or Wii, and the Voip Adapter in the same home network, you’d better set codec to G.729 to save the bandwidth and get better voice quality.

 

 

IP Ports and Protocols

The following IP Ports and Protocols are excerpted from Networking Fundamentals.
Port number – Protocols name
20 – File Transfer Protocol (FTP) data
21 – File Transfer Protocol (FTP) control
23 – Telnet
25 – Simple Mail Transfer Protocol (SMTP)
53 – Domain Name Service (DNS)
80 – HyperText Transfer Protocol (HTTP)
110 – Post Office Protocol version 3 (POP3)
119 – Network News Transport Protocol (NNTP)
139 – NetBIOS Session Service
143 – Internet Message Access Protocol (IMAP)
161 – Simple Network Management Protocol (SNMP)
Common protocols include TCP, UDP and ICMP. There are actually a great number of protocols, but these three are the most prevalent. TCP is used to handle the underlying data streams for web, email, news and almost every other popular network application. That does not mean that UDP and ICMP are not important however.

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Install NetBEUI on Windows XP

I found some error in the event log on one of my Windows XP computer.
It said something like
NetBEUI service is not start
After doing some searchs I got the official way to install it to remove this error.
I don’t know how it is happened. The installation is old, for more than one year. But I just changed some parts of this computer, including mother board, CPU, Case, Audio Card, and memory.
So firstly, I remove the NetBEUI protocol from the list of protocols in the adapter properties.
Restart computer.
Follow the official way to install the NetBEUI protocol.
Restart again.
The error gone.

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