Chief Transmission and Switching Engineer(JP

Let's do study and measures of "Telecommunication chief engineer examination" where a good teaching material doesn't exist though the examination contents is advanced little by little.

2010/10/30

It is a problem that becomes familiar and is deep. TCP/IP

Sleep today's problem of delivering a basic problem of TCP/IP is a problem of Internet Protocol address.
If the person has challenged CCNA etc. , I think that it is a simple problem very much.

Then, today's material is [kochira] ↓↓.



- Internet Protocol address (IPv4)



Internet Protocol address composed of the binary number in 32 bits divides into the network part and the host part, the network part is used to distinguish and to identify the belonging network, and the host part is used to identify the computer in the belonging network etc.

These sentences are correct.
- The computer in the network that * host part = belongs that distinguishes the network that network part = belongs and identifies it etc. are identified.



It usually delimits every eight bits, and each item is shown by the hexadecimal number, and Internet Protocol address ties at the period and writes between those.

These sentences are wrong.
- It is not a hexadecimal number and the decimal number of Internet Protocol address.



There are some classes in Internet Protocol address, and class B for a small-scale network is used for class C for a medium-scale network among these for the large scale network as for class A. Moreover, the number of bits of network parts is fixation regardless of the class.

These sentences are wrong.
- For large scale network ..class A.., and for ..class C.. small-scale network
- 【 number of bits of network parts 】 is different in each class (A=8 bit, B=16 bit, and C=24 bit).



How?It is already a level somehow like the quiz rather than the examination paper. Such a score source the service problem sleeps ..doing Get surely.. and, then, : settling down, reading the problem, and taking care not to hang to a trivial hanging around here today.

2010/10/23

The layer model of TCP/IP is set.

Hello.
Today's chief telecommunications engineer's problem is delivered by the TCP/IP relation. Please work lightly because it is feeling like a basic problem of OSI reference model who tend to be very very. Then, today's problem is [kochira] ↓↓.



- Layer model of TCP/IP in the wide sense



Being located in the highest layer is a network interface layer, and the function to achieve the communication on the transmission line between the adjoining nodes is possessed.

These sentences are wrong.
- It is a layer model of TCP/IP, "Network interface layer" is an undermost layer, and the highest layer is an application layer. 。。



The Internet layer has the function to do [ru-chingu] such as IP packets, and there is IP in the protocol in this layer.

These sentences are correct.
- Because the Internet layer is a hierarchy to which OSI reference model's "Network layer" corresponds, these sentences are answered correctly.



The transport layer enables the communication between the applications that a different host has, and there is Telnet in the protocol in this layer.

These sentences are wrong.
- It shall not not be a transport layer, and the application layer be none here. 。。



In the application layer, there are a lot of protocols used for a specific application, and are a FTP for the file transfer, SMTP for network management, and SNMP for the E-mail forwarding, etc.

These sentences are wrong.

- ..network management.. SMTP for the E-mail forwarding ..SMTP.. reverses by feeling.



How?・・・ though chief telecommunications engineer's qualification is acquired easily when increasing .."Service problem".. a little more ..so.. Then around here today

2010/10/21

Though the problem is H.323

Well, I feel the base of TCP/IP more than saying as for "H.323" though today's chief telecommunications engineer's material is H.323. It neatly examines if it is not good around here because it is knowledge that the problem of the voice coding is not limited to H.323 this time and the protocol of the voice call makes indispensable, it acquires, it sleeps, and, then, today's material is [kochira] ↓↓.



- Recommendations such as encoding of voice in Internet protocol telephone in accordance with ITU-T recommendation H.323 and making to packet and protocols



In one of the encoding methods of the voice, there is an encoding method by PCM with the transmission speed of 64Kbit/s provided for by ITU-T recommendation G and 711.

These sentences are correct.
- There is μ-LAW or a-LAW in G.711, both are encoded by eight bits, and the transmission speed is 64Kbit/s.
- Signal vs. warp performance of μ-law in a low-level signal is higher than that of A-law.
- The dynamic range of A-law is wider than that of μ-law.
- The μ-law adoption nations will be doing conversion from μ to A use A-law in an international connection.



The voice packet of the Internet protocol telephone is transmitted by using not TCP but UDP as a protocol in the transport layer because real time is demanded, and using RTP as a high-ranking protocol in the transport layer.

These sentences are correct.
- Real time is UDP+RTP if said.



When the delivery confirmation of the IP packet is done, and it is not possible to transmit, it sends it again in UDP though the transmittal confirmation of the IP packet is not done in TCP.

These sentences are wrong.

- TCP is ♪ three way handshaking that does the delivery confirmation.



RTP has the function of the annulment of the packet with a large delay etc. in the protocol to send the real-time data in the voice and animation, etc.

These sentences are correct.
- RTP annuls the packet with a large delay.



Well, how?
Apart from three sentences in the latter half
Do not it be easy remember considerably and does not fight hard against the first G.711?
When easily introducing it

G.711(PCM)・・・IP net in telephone network and enterprise chiefly
G.726(ADPCM)・・・PHS etc. for the main.
G.723.1(ACELP)・・・IP net in enterprise Internet phone/chiefly
G.729(CS-ACELP)・・・IP net in cellular phone and enterprise chiefly
G.722(SB-ADPCM) ・・・IP net in enterprise chiefly



Is it such feeling in the main point?
It easily thinks information around here to obtain fully when googling and seeing and examine it once, please.
Then, around here today

2010/10/16

SIP(Session Initiation Protocol) and ITU-T recommendation H.323

Well, the material of the study of today's chief telecommunications engineer is SIP. Well, common sense or an easy problem is considerably sulky and, then, today's material is [kochira] ↓↓ though it is an outline problem of SIP and H.323.



- SIP(Session Initiation Protocol) and ITU-T recommendation H.323



SIP is standardized by IETF, and a multi half of the message in SIP is described by the binary form.

These sentences are wrong.
- It is not a binary, and the text form of SIP.



ITU-T recommendation H.323 is composed of two or more protocols that provide for the call control of the terminal and the method of encoding the voice and the image etc.

These sentences are correct.
- H.323 is composed of two or more protocols.



H.323MCU(Multipoint Control Unit) that is one of the components of the telecommunication system in accordance with ITU-T recommendation H.323 offers a function necessary to achieve the multi point communication (communication done with three terminals or more).

These sentences are correct.
- "Multi point communication" is " MCU " in H.323 if said.



Well, how? The message of SIP is thought that the text is common sense and I think that it is understood that H.323 is composed of two or more protocols. MCUI distributes the packet to the terminal when it will quote it from Wiki by abbreviating Multipoint Control Unit, and is an equipment of the teleological conference etc. the third MCU that communicates between multi points. MCU manages the resource of the conference, does the negotiation between terminals, and, according to circumstances, treats the media streams. It is also possible that MCU makes them coexist on the same device as the gateway and the gatekeeper. ・・・ It is remembered that it is not only H.323 exclusive use though it becomes because there are SIP and the corresponding one according to ..MCU.. product, too. Then, around here today

2010/10/09

Outline of connected processing of SIP used with VoIP net

Hello I think that today's material goes with SIP. Well, because the knowledge of SIP has the part that is already common sense in the network industry and the telecom industry, the chief telecommunications engineer's examination knows the minimum any more though thinks the problem of SIP to be frequent occurrence. It is not the one that today's material judges "Corrections of sentences" as usual, and it is good ..only reading for the time being... If it doesn't have it, knowledge at today's problem level doesn't become work though it is a request substantially message of SIP ・・・ It is not likely to be able to use, and even the packet capture doesn't understand the meaning as the protocol analyzer is also satisfactory. Then, today's material is [kochira] ↓↓.



- Outline of connected processing of SIP used with VoIP net



The message of SIP includes request (demand) message and response (response) messages. As for the request message, six kinds are standardized by RFC3261 among these.
- There is request (demand) message and response (response) message = messages of SIP.



The request message of SIP is said 【 method 】 in general, and the main usage is as follows.
- In general, the request message of SIP is said 【 method 】.



A: INVITE is the first request message used to establish the session between user agent.
- The first request message used to establish the session between INVITE = user agent



B: 【ACK】 is a request message used to confirm the response message to INVITE was received, and the media session can be established by 【ACK】 for the communication.
- 【ACK】 In the request message used to confirm the response message to = INVITE was received, the media session can be established by 【ACK】 for the communication.



C: BYE can be sent from either the caller or the receiver by the request message used to end the set media session.
- It is possible to send it from either the caller or the receiver by the request message used to end the media session BYE = set.



D: CANCEL corresponds to breaking the connection before the other party responds when calling it before the media session is established by the request message used to discontinue setting.
- It corresponds to breaking the connection before the other party responds when calling it before the media session is established CANCE L = by the request message used to discontinue setting.



E: When the user agent registers 【URI】 that is my location information (location information) and Internet Protocol address to the SIP network, RESISTER is used.
- When RESISTER = user agent registers 【URI】 that is my location information (location information) and Internet Protocol address to the SIP network, it is used.



F: When the user agent inquires the ability and the state to other user agent and 【 proxy 】 server, OPTIONS is used.
- When OPTIONS = user agent inquires the ability and the state to other user agent and 【 proxy 】 server, it is used.



Well, how though this blog is not considerably seen easily because the frame is small? A person not good at the SIP related problem : sleeping ..study hard.. then around here today because there might be a hindrance also in the business not to mention the examination if it doesn't come to be able to judge the state by seeing CallSequence though it was a problem of the SIP request message.

2010/10/02

SIP(Session Initiation Protocol) and ITU-T recommendation H.323

Well, the material of the study of today's chief telecommunications engineer is SIP. Well, ↓↓ then ..this right under today's material.. though it is an outline problem of SIP and H.323. sulky an easy problem common sense considerably



- SIP(Session Initiation Protocol) and ITU-T recommendation H.323




SIP is standardized by IETF, and a multi half of the message in SIP is described by the binary form.

These sentences are wrong.
- It is not a binary, and the text form of SIP.



ITU-T recommendation H.323 is composed of two or more protocols that provide for the call control of the terminal and the method of encoding the voice and the image etc.

These sentences are correct.
- H.323 is composed of two or more protocols.



H.323MCU(Multipoint Control Unit) that is one of the components of the telecommunication system in accordance with ITU-T recommendation H.323 offers a function necessary to achieve the multi point communication (communication done with three terminals or more).

These sentences are correct.
- "Multi point communication" is " MCU " in H.323 if said.



Well, how? The message of SIP is thought that the text is common sense and I think that I understand H.323 is composed of two or more protocols. MCUI distributes the packet to the terminal when it will quote it from Wiki by abbreviating Multipoint Control Unit, and is an equipment of the teleological conference etc. the third MCU that communicates between multi points. MCU manages the resource of the conference, does the negotiation between terminals, and, according to circumstances, treats the media streams. It is also possible that MCU makes them coexist on the same device as the gateway and the gatekeeper. ・・・ It is remembered that it is not only H.323 exclusive use though it becomes because there are SIP and the corresponding one according to ..MCU.. product, too. Then, around here today

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