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Exercício em Tamanho de Janelas na Internet
Você está agindo como um emissor em uma conexão TCP, e você tem 107k 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: 1K. – Parâmetro limitante inicial: 8K.
Destino tem 12K 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 7a mensagem, mas esta é reenviada com sucesso antes de enviar a 8a mensagem.
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Você pode preencher essa tabela?
Depois dessas mensagens… A janela de congestiona-mento é … A janela de controle de fluxo é … O número de bytes dessa mensagem
0 (valor inicial) (valor inicial) (não aplicável)
1 ? ? ? 2 ? ? ? … … … … n ? ? ? 2K 2K
Mensagem 1
1KQuantidade deixada para enviar: 217K
Janela de Controle de Congestionamento :
Janela Limitante de Congestionamento: 8K
Janela de Controle de Fluxo: 24K 1K 106K 11K 22K9K 4K 4K 215K 105K
Mensagem 2
1KAmount left to send:
Congestion control window:
Congestion threshold: 8K
Flow control window: 2K
5 211K 101K 18K5K 8K 8K
Mensagem 3
1KAmount left to send:
Congestion control window:
Congestion threshold: 8K
Flow control window: 4K 2K 2K 2K 6 8K 10K0K 203K96K
Mensagem 4
1KAmount left to send:
Congestion control window:
Congestion threshold: 8K
Flow control window: 5K 2K 2K 1K 2K 2K 2K 0K 12K 96K 8K
Receiver picks up data
2K
Amount left to send:
Congestion control window:
Congestion threshold: 8K
Flow control window:
2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 24K4K 16K9K 193K88K
Mensagem 5
Amount left to send:
Congestion control window:
Congestion threshold: 8K
Flow control window: 8K
2K 2K
9 8K 0K 9K 177K84K
Mensagem 6
Amount left to send:
Congestion control window:
Congestion threshold: 8K
Flow control window: 4K 2K 2K 2K 2K 2K 2K 10 0K 12K 84K 9K
Receiver picks up data
2K
Amount left to send:
Congestion control window:
Congestion threshold: 8K
Flow control window:
2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 10K 84K 12K
Message 7
Amount left to send:
Congestion control window:
Congestion threshold: 8K
Flow control window:
9K 73K75K
24K3K 26K1K
Re-send message 7
Amount left to send:
Congestion control window:
Congestion threshold: 16K
Flow control window: 9K 2K 2K 2K 2K 1K 5K
13 49K 73K 2K 2K
Message 8
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window: 24K 2K 1K 2K 2K 2K 2K 2K 1K 14 49K 72K 2K 2K
Message 9
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window: 24K 1K 0K 2K 2K 2K 2K 2K 2K 0K 12K 72K 2K
Receiver picks up data
2K
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window:
2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 47K70K 22K 10K 4K 4K
Message 10
2KAmount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window: 2K
17 43K 66K 18K6K 8K 8K
Message 11
2KAmount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window: 4K 2K 2K 18 35K 60K 8K 10K0K
Message 12
2KAmount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window: 6K 2K 2K 2K 2K 2K 0K 12K 60K 8K
Receiver picks up data
2K
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window:
2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 24K4K 25K 52K 13K9K
Message 13
2KAmount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window: 8K
2K 2K
21 12K 48K 9K 11K0K
Message 14
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window: 4K 2K 2K 2K 2K 2K 2K 22 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 1K 1K 0K 12K 48K 9K
Receiver picks up data
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window:
1K 39K
10K
24K3K
Message 15
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window: 9K 1K 2K 2K 2K 2K 151K36K 10K 6K 0K
Message 16
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window: 3K
2K 2K
2K 2K
25 0K
12K 36K
10K
Receiver picks up data
2K
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window:
2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 26 145K26K 24K 20K 11K 2K
Message 17
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window: 10K 2K 2K 2K 2K 2K 125K24K 4K 0K 11K
Message 18
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window: 2K 2K 2K 2K 2K 2K 2K 0K 12K 24K 11K
Receiver picks up data
2K
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window:
2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K
29 125K13K 4K 1K 12K
Message 19
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window: 11K 2K 1K 2K 2K 2K 2K 30 125K12K 4K 0K 12K
Message 20
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window: 1K 2K 2K 2K 2K 2K 2K 0K 12K 12K 12K
Receiver picks up data
2K
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window:
2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 125K0K 4K 0K 12K
Message 21
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window: 12K
2K 2K
2K 2K
33 0K
12K 0K
12K
Receiver picks up data
2K
Amount left to send:
Congestion control window:
Congestion threshold: 5K
Flow control window:
2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 34 After this many messages… Congestion
window is… Flow control window is… Number of bytes in this message 0 1K 12K (not applicable) 1 2K 11K 1K 2 4K 9K 2K 3 8K 5K 4K 4 8K 12K 5K 5 9K 4K 8K 6 10K 12K 8K 7 1K 2K 4K 8 2K 12K 10K 9 4K 10K 2K 10 8K 6K 2K 11 9K 12K 4K 12 After this many messages… Congestion
window is… Flow control window is… Number of bytes in this message 12 10K 3K 9K 13 11K 12K 3K 14 12K 1K 11K 15 13K 12K 12K 16 14K 12K 12K 17 15K 12K 12K 18 16K 12K 12K 19 20 21 12
