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Zorluk: OrtaTFTP and FTP Operations for System Images and Configuration Management

A network engineer is transferring a 450 MB Cisco IOS XE system image across a high-latency WAN connection to a branch router. Initial transfer attempts using TFTP fail due to frequent timeouts and poor throughput over the lossy link. The engineer switches the process to use FTP, and the image file transfers completely without error. Which operational characteristic of FTP explains why it succeeds over high-latency, lossy connections where TFTP fails?

  1. FTP operates over TCP, leveraging sliding windows and sliding sequence acknowledgments for reliable flow control and packet loss recovery.Cevap
  2. B
    TFTP uses UDP port 69 with built-in TCP-style sliding window flow control that drops sessions when round-trip delay exceeds 100 milliseconds.
  3. C
    FTP uses UDP for high-speed bulk data transport across WAN links, avoiding the overhead of connection establishment handshakes.
  4. D
    TFTP establishes dual TCP control and data channels that require persistent low-latency synchronization between endpoints.

Cevap

FTP operates over TCP, leveraging sliding windows and sliding sequence acknowledgments for reliable flow control and packet loss recovery.
The option identifying FTP's use of TCP sliding windows and acknowledgments is correct. FTP uses TCP as its transport protocol, which provides full reliability mechanisms including sequence numbering, windowing, and selective/cumulative retransmissions. This allows FTP to efficiently handle packet drops and latency over WAN links without timing out the overall session.

Adım Adım Çözüm

1
Analyze transport protocol mechanics for TFTP and FTP.
TFTP operates over UDP port 69 and uses lockstep acknowledgment (each block must be individually acknowledged before the next is sent). FTP operates over TCP (ports 20 and 21) and uses connection-oriented dynamics.
Transport layer mechanisms dictate file transfer behavior over lossy or delayed networks.
2
Evaluate impact of high latency and packet loss on lockstep vs windowed transfers.
On high-latency links with loss, TFTP lockstep acknowledgments experience severe throughput degradation and frequent timeouts. FTP's TCP windowing and dynamic retransmissions recover lost segments seamlessly.
TCP sliding windows allow multiple unacknowledged packets in transit, maximizing bandwidth utilization.

Anahtar Kavram

Operational characteristics and transport mechanics of TFTP vs FTP file transfers
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Konular

TFTP and FTP Operations for System Images and Configuration Management

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