Edición de «Fórmulas Primer parcial (Teoría de las Comunicaciones)»

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==== Bandwidth and latency ====
*Latency = Propagation + Transmit + Queue
*Propagation = Distance/SpeedOfMedium
*Transmit = Size/Bandwidth

==== Shannon's Theorem ====
<math>C = B \times log_2 (1 + S/N)</math>
*B es el ancho de banda
*C es la capacidad
*S/N es la relacion señal ruido en dB

==== Subnetting ====
Applying a subnet mask to an IP address allows you to identify the network and node parts of the address. The network bits are represented by the 1s in the mask, and the node bits are represented by the 0s. Performing a bitwise logical AND operation between the IP address and the subnet mask results in the Network Address or Number.

For example, using our test IP address and the default Class B subnet mask, we get:

 10001100.10110011.11110000.11001000      140.179.240.200   IP Address
 11111111.11111111.00000000.00000000      255.255.000.000   Default Subnet Mask
 --------------------------------------------------------
 10001100.10110011.00000000.00000000      140.179.000.000   Network Address

To calculate the number of subnets or nodes, use the formula (<math>2^n-2</math>) where n = number of bits in either field, and <math>2^n</math> represents 2 raised to the nth power. Multiplying the number of subnets by the number of nodes available per subnet gives you the total number of nodes available for your class and subnet mask. Also, note that although subnet masks with non-contiguous mask bits are allowed, they are not recommended.

Example:

 10001100.10110011.11011100.11001000      140.179.220.200   IP Address
 11111111.11111111.'''111'''00000.00000000      255.255.224.000   Subnet Mask
 --------------------------------------------------------
 10001100.10110011.11000000.00000000      140.179.192.000   Subnet Address
 10001100.10110011.11011111.11111111      140.179.223.255   Broadcast Address

In this example a '''3 bit''' subnet mask was used. There are 6 (<math>2^3-2</math>) subnets available with this size mask ('''remember that subnets with all 0's and all 1's are not allowed'''). Each subnet has 8190 (<math>2^{13}-2</math>) nodes. Each subnet can have nodes assigned to any address between the Subnet address and the Broadcast address. This gives a total of 49,140 nodes for the entire class B address subnetted this way.

You can calculate the '''Subnet Address''' by performing a bitwise logical AND operation between the IP address and the subnet mask, then setting all the host bits to 0s. Similarly, you can calculate the '''Broadcast Address''' for a subnet by performing the same logical AND between the IP address and the subnet mask, then setting all the host bits to 1s. That is how these numbers are derived in the example above.

[[Category:Apuntes]]
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-{{Back|Teoría de las Comunicaciones}}
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-== Performance ==
+==== Bandwidth and latency ====
+*Latency = Propagation + Transmit + Queue
+*Propagation = Distance/SpeedOfMedium
+*Transmit = Size/Bandwidth
-'''Nota: Throughput = Bandwidth'''
-==== Latency/Throughput ====
-* Latency = RTT/2 = PropagationDelay + TransmitDelay + QueueDelay
-* PropagationDelay = Distance/SpeedOfMedium
-* TransmitDelay = TransmitSize/Bandwidth
-== Teoría de la Información ==
 ==== Shannon's Theorem ====
 <math>C = B \times log_2 (1 + S/N)</math>
-* B es el ancho de banda
+*B es el ancho de banda
-* C es la capacidad
+*C es la capacidad
-* S/N es la relacion señal ruido, generalmente dada en db
+*S/N es la relacion señal ruido en dB
-* Vale 1db = 10 log10 (S/N)
-==== Información de un evento ====
-<math>I(e) = -log_2(P(e))</math>
-==== Entropía ====
-Cantidad media de información por símbolo
-<math>H(s) = -\sum_{e \in s} P(e)log_2(P(e)) = \sum_{e \in s} P(e) I(e) </math>
-==== Inecuacion de Kraft ====
-Condicion necesaria y suficiente para la existencia de un codigo instantaneo
-<math>\sum_{e \in s} 2^{-l_e} \leq 1</math>
-==== Longitud media ====
-<math>L(s) = \sum_{e \in s} P(e) l_e </math>
-==== Condicion necesaria para univoco ====
+==== Subnetting ====
+Applying a subnet mask to an IP address allows you to identify the network and node parts of the address. The network bits are represented by the 1s in the mask, and the node bits are represented by the 0s. Performing a bitwise logical AND operation between the IP address and the subnet mask results in the Network Address or Number.
-<math>H(s) \leq L(S)</math>
+For example, using our test IP address and the default Class B subnet mask, we get:
-* La igualdad se verifica cuando los logaritmos de las inversas de las probabilidades (los ''I(e)'') son nros enteros.
+ 10001100.10110011.11110000.11001000      140.179.240.200   IP Address
+ 11111111.11111111.00000000.00000000      255.255.000.000   Default Subnet Mask
+ --------------------------------------------------------
+ 10001100.10110011.00000000.00000000      140.179.000.000   Network Address
-==== Tasa de informacion ====
+To calculate the number of subnets or nodes, use the formula (<math>2^n-2</math>) where n = number of bits in either field, and <math>2^n</math> represents 2 raised to the nth power. Multiplying the number of subnets by the number of nodes available per subnet gives you the total number of nodes available for your class and subnet mask. Also, note that although subnet masks with non-contiguous mask bits are allowed, they are not recommended.
-<math>R = r * H(s)</math>
+Example:
-* R se mide en bits/tiempo
-* r es cantidad de simbolos/tiempo
-* r se calcula en funcion de la longitud media y el tiempo por pulso binario
-== Hamming ==
+ 10001100.10110011.11011100.11001000      140.179.220.200   IP Address
-La distancia de Hamming indica cuantos bits es necesario como minimo que sean erroneos para lograr engañar al codigo.
+ 11111111.11111111.'''111'''00000.00000000      255.255.224.000   Subnet Mask
-* Si <math>d = n+1</math>, es posible detectar errores de hasta ''n'' bits.
+ --------------------------------------------------------
-* Si <math>d \geq 2m + 1</math>, es posible corregir errores de hasta ''m'' bits.
+ 10001100.10110011.11000000.00000000      140.179.192.000   Subnet Address
+ 10001100.10110011.11011111.11111111      140.179.223.255   Broadcast Address
-== Sliding window ==
+In this example a '''3 bit''' subnet mask was used. There are 6 (<math>2^3-2</math>) subnets available with this size mask ('''remember that subnets with all 0's and all 1's are not allowed'''). Each subnet has 8190 (<math>2^{13}-2</math>) nodes. Each subnet can have nodes assigned to any address between the Subnet address and the Broadcast address. This gives a total of 49,140 nodes for the entire class B address subnetted this way.
-* Debe cumplirse que <math>2^{seqbits} \ge E+R</math> donde E y R son las ventanas de emisor y receptor. Si se verifica la formula se elimina el solapamiento.
-* El tamaño de la ventana de emision se calcula como RTT * Vtx / FrameSize
-== Internetworking ==
+You can calculate the '''Subnet Address''' by performing a bitwise logical AND operation between the IP address and the subnet mask, then setting all the host bits to 0s. Similarly, you can calculate the '''Broadcast Address''' for a subnet by performing the same logical AND between the IP address and the subnet mask, then setting all the host bits to 1s. That is how these numbers are derived in the example above.
-*Tamaño del header IP: 20 bytes
-*El offset de un paquete fragmentado se mide en '''multiplos de 8 bytes'''.
 [[Category:Apuntes]]