Tag: TCP/IP

MPLS

Posted on by lechuck park

From Claude with some prompting
Let me explain this MPLS (Multiprotocol Label Switching) diagram:

  1. Left Section – Network Stack:
  • Application layer
  • TCP/UDP layer
  • IP layer
  • Ethernet layer
  1. Middle Section – MPLS Label Structure:
  • Label (20 bits): Used for routing
  • Experimental (3 bits): For QoS (Quality of Service) priority
  • Bottom of Stack (1 bit): Indicates if it’s the last label (Not Bottom: 0)
  • TTL (8 bits): Time to Live, prevents looping
  1. Right Section – MPLS Network Operation:
  • Label Edge Router (LER): Adds/removes labels at network boundaries
  • Label Switching Router (LSR): Performs label-based switching
  • Packets expire when TTL reaches 0
  • Routing based on priority using Experimental (QoS) bits

Operational Flow:

  1. Add Label Header: When packets enter MPLS network
  2. Routing by Label: Packet forwarding based on labels with Priority by Exp(QoS)
  3. Remove Label Header: When packets exit MPLS network

Key Benefits of MPLS:

  • Fast packet forwarding (label-based switching)
  • QoS support
  • Efficient traffic engineering
  • Support for multiple network protocols

The diagram shows how MPLS creates a more efficient and manageable network by using label-based forwarding instead of traditional IP routing. Labels can be stacked (Label Stack-able) for more complex routing scenarios, and the TTL field helps prevent infinite routing loops.

Lechuck History

Posted on by lechuck park

From Claude with some prompting
“Lechuck History” diagram demonstrates the following technical career progression:

  1. “with Computer” section:
    • Advanced from C-based programming to system programming, O&M solutions, and network programming
    • Possess deep understanding of Linux kernel, RTOS, and TCP/IP stack
    • Performed “Single-Handedly A to Z” tasks in web service analysis/monitoring
    • Grew into the role of a software engineer
  2. “with People” section:
    • Gained experience in large ISP data centers, system management, large-scale network operations management, and CDN development/management
    • Developed skills to optimize and maximize existing system infrastructure
    • Created new service solutions including D/C business web portals, NMS big-data, DCIM, packet analysis customer solutions, and data analysis platforms
    • Managed “Big DC Op. System Design & DevOps”, demonstrating ability to handle customer-facing roles and collaborate with various partners

Additional key competencies:

  1. Maintain continuous interest in new technologies
  2. Possess the ability to quickly learn based on a solid understanding of fundamentals
  3. Currently enjoy learning cutting-edge technologies including AI and Quantum computing

This career path and skill set demonstrate the profile of a professional who continuously grows and pursues innovation in a rapidly changing technological environment.

Traceroute

Posted on by lechuck park

From Claude with some prompting
This image explains the concept of “Traceroute: First Send, First Return?” for the traceroute utility in computer networking. Traceroute sends IP packets with increasing Time-to-Live (TTL) values, starting from TTL=1, 2, 3, and so on. When the TTL reaches 0 at a network hop, that hop returns an ICMP (Internet Control Message Protocol) message back to the source.

However, the order in which the response packets are received at the source may differ from the order in which they were sent, primarily due to two reasons:

  1. Generation of ICMP response packets is a CPU task, and it can be delayed due to CPU settings or other processing priorities, causing a delay in the response.
  2. The ICMP response packets can take multiple paths to return to the source, as indicated by the text “Packet replies can use multiple paths” in the image. This means that responses can arrive at different times depending on the route taken.

As a result, when analyzing traceroute results, it is essential to consider not only the TTL sequence to determine the network hops but also factors like response times and paths taken by the responses.

The potential delay in ICMP packet generation by the CPU and the use of multiple return paths can cause the actual response order to differ from the sending order in traceroute.

Understanding that the response order may not strictly follow the sending order due to CPU processing delays and the use of multiple return paths is crucial when interpreting traceroute results.