Exercício em Tamanho de Janelas na Internet

Você está agindo como um emissor em uma conexão TCP, e
você tem 217k bytes de dados para enviar. Na conexão, você
concorda que o TCP utiliza o algoritmo de inicialização lenta
(slow start) com um terceiro parâmetro, o limitante (threshold):
– Tamanho do segmento inicial: 2K.
– Parâmetro limitante inicial: 16K.

Destino tem 24K de buffer (janela do receptor).
– Usuário destino somente pega os dados quando o buffer
receptor estiver cheio.
– Para um buffer parcialmente cheio, a janela de controle de
fluxo é reduzida para o espaço atual restante no buffer.

O tempo expira na 14a mensagem, mas esta é reenviada com
sucesso antes de enviar a 15a mensagem.
1
Você pode preencher essa tabela?
A janela de
Depois
congestionadessas
mensagens… mento é …
(valor inicial)
0
A janela de
controle de
fluxo é …
(valor inicial)
O número de
bytes dessa
mensagem
(não aplicável)
1
?
?
?
2
?
?
?
…
…
…
…
n
?
?
?
2
Mensagem 1
Quantidade deixada para enviar:
217K
215K
2K
2K
Janela de Controle de Congestionamento :
4K
2K
Janela de Controle de Fluxo:
Janela Limitante de Congestionamento:
24K
22K
16K
3
Mensagem 2
Amount left to send:
2K
2K
2K
215K
211K
4K
Congestion control window:
8K
4K
Flow control window:
Congestion threshold:
18K
22K
16K
4
Message 3
Amount left to send:
203K
211K
8K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
16K
8K
Flow control window:
Congestion threshold:
10K
18K
16K
5
Message 4
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
16K
2K
2K
193K
203K
10K
Flow control window:
Congestion threshold:
10K
0K
16K
6
Receiver picks up data
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
16K
2K
2K
193K
Flow control window:
Congestion threshold:
24K
0K
16K
7
Message 5
Amount left to send:
177K
193K
16K
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
18K
16K
Flow control window:
Congestion threshold:
24K
8K
16K
8
Message 6
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
18K
2K
2K
169K
177K
8K
Flow control window:
Congestion threshold:
0K
8K
16K
9
Receiver picks up data
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
18K
2K
2K
169K
Flow control window:
Congestion threshold:
24K
0K
16K
10
Message 7
Amount left to send:
151K
169K
18K
Congestion control window:
2K
2K
2K
2K
2K
2K
2K
2K
2K
20K
18K
Flow control window:
Congestion threshold:
24K
6K
16K
11
Message 8
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
20K
2K
2K
145K
151K
6K
Flow control window:
Congestion threshold:
0K
6K
16K
12
Receiver picks up data
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
20K
2K
2K
145K
Flow control window:
Congestion threshold:
24K
0K
16K
13
Message 9
Amount left to send:
125K
145K
20K
Congestion control window:
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
22K
20K
Flow control window:
Congestion threshold:
24K
4K
16K
14
Message 10
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
22K
2K
2K
121K
125K
4K
Flow control window:
Congestion threshold:
0K
4K
16K
15
Receiver picks up data
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
22K
2K
2K
121K
Flow control window:
Congestion threshold:
24K
0K
16K
16
Message 11
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
24K
22K
2K
121K
99K
22K
Flow control window:
Congestion threshold:
24K
2K
16K
17
Message 12
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
24K
2K
2K
97K
99K
2K
Flow control window:
Congestion threshold:
0K
2K
16K
18
Receiver picks up data
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
24K
2K
2K
97K
Flow control window:
Congestion threshold:
24K
0K
16K
19
Message 13
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
26K
24K
2K
2K
73K
97K
24K
Flow control window:
Congestion threshold:
24K
0K
16K
20
Receiver picks up data
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
26K
2K
2K
73K
Flow control window:
Congestion threshold:
24K
0K
16K
21
Message 14
Amount left to send:
73K
24K
Congestion control window:
26K
Flow control window:
Congestion threshold:
24K
16K
22
Re-send message 14
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
26K
2K
2K
2K
49K
73K
24K
Flow control window:
Congestion threshold:
24K
0K
16K
13K
23
Receiver picks up data
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
2K
2K
2K
49K
Flow control window:
Congestion threshold:
24K
0K
13K
24
Message 15
Amount left to send:
2K
47K
49K
2K
Congestion control window:
4K
2K
Flow control window:
Congestion threshold:
24K
22K
13K
25
Message 16
Amount left to send:
2K
2K
2K
43K
47K
4K
Congestion control window:
8K
4K
Flow control window:
Congestion threshold:
18K
22K
13K
26
Message 17
Amount left to send:
35K
43K
8K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
13K
8K
Flow control window:
Congestion threshold:
10K
18K
13K
27
Message 18
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
13K
2K
2K
25K
35K
10K
Flow control window:
Congestion threshold:
10K
0K
13K
28
Receiver picks up data
Amount left to send:
2K
2K
2K
2K
2K
2K
2K
2K
Congestion control window:
2K
2K
13K
2K
2K
25K
Flow control window:
Congestion threshold:
24K
0K
13K
29
Message 19
Amount left to send:
12K
25K
13K
2K
2K
2K
2K
2K
2K
1K
Congestion control window:
15K
13K
Flow control window:
Congestion threshold:
24K
11K
13K
30
Message 20
Amount left to send:
2K
2K
2K
2K
2K
2K
1K 1K
2K
Congestion control window:
2K
2K
15K
2K
2K
12K
1K
11K
Flow control window:
Congestion threshold:
11K
0K
13K
31
Receiver picks up data
Amount left to send:
2K
2K
2K
2K
2K
2K
1K 1K
2K
Congestion control window:
2K
2K
15K
2K
2K
1K
Flow control window:
Congestion threshold:
24K
0K
13K
32
Message 21
Amount left to send:
1K
0K
1K
1K
Congestion control window:
15K
Flow control window:
Congestion threshold:
23K
24K
13K
33
After this
many
messages…
0
1
2
3
4
5
6
7
8
9
10
11
Congestion
window is…
2K
4K
8K
16K
16K
18K
18K
20K
20K
22K
22K
24K
Flow control
window is…
24K
22K
18K
10K
24K
8K
24K
6K
24K
4K
24K
2K
Number of
bytes in this
message
(not applicable)
2K
4K
8K
10K
16K
8K
18K
6K
20K
4K
22K
12
34
After this
many
messages…
11
12
13
14
15
16
17
18
19
20
21
Congestion
window is…
Flow control
window is…
24K
24K
26K
2K
4K
8K
13K
13K
15K
15K
15K
2K
24K
24K
24K
22K
18K
10K
24K
11K
24K
23K
Number of
bytes in this
message
22K
2K
24K
24K
2K
4K
8K
10K
13K
11K
1K
12
35