Latency, Jitter, Packet Loss

 

 Latency

Latency is the actual time taken for data to travel from one point to another.

In networking, latency is essentially the end-to-end delay experienced by a packet.

Example

You ping Google's DNS server.

Reply from 8.8.8.8: time=25ms

The latency is 25 ms.

Lower latency means a faster response.

Typical values:

  • 1–20 ms → Excellent (LAN)
  • 20–50 ms → Very good
  • 50–100 ms → Acceptable

  • 150 ms → Noticeable delay

  • 300 ms → Poor for interactive applications

Jitter

Jitter is the variation in packet delay.

If every packet takes exactly the same amount of time, jitter is zero.

If packet delays fluctuate, jitter increases.

Example

Packet delays:

20 ms
21 ms
20 ms
22 ms
21 ms

Jitter is very low.

Now consider:

20 ms
45 ms
18 ms
70 ms
30 ms

Jitter is high because packet arrival times vary significantly.

Why is jitter bad?

Applications like:

  • Voice over IP (VoIP)
  • Video calls
  • Online gaming
  • Live streaming

need packets to arrive at regular intervals.

High jitter causes:

  • Choppy audio
  • Frozen video
  • Robotic voices
  • Lag during gaming

Packet Loss

Packet loss occurs when one or more packets never reach their destination.

It is expressed as a percentage.

Example

You send 100 packets.

Only 97 arrive.

Packet loss:

3%

Common Causes

  • Network congestion
  • Damaged cables
  • Faulty hardware
  • Wireless interference
  • Router CPU overload
  • Full interface queues
  • Misconfigured QoS

Effects

  • Slow downloads
  • Broken voice calls
  • Video buffering
  • Retransmissions
  • Poor application performance

Comparison Table

MetricMeaningUnitIdeal Value


LatencyEnd-to-end travel time experienced by a packetmsLow
JitterVariation in packet arrival timesmsClose to 0
Packet LossPercentage of packets that never arrive%0%

Comments

Post a Comment

Popular posts from this blog

🖧 VLAN (Virtual Local Area Network)

  🖧 VLAN (Virtual Local Area Network) 🧠 Top 5 Key Points Logical Network Segmentation: VLANs divide a physical network into multiple logical networks , thus breaking broadcast domain. Improved Security: Devices in different VLANs cannot communicate unless explicitly allowed via a router or Layer 3 switch . Reduces Broadcast Domains: Each VLAN is its own broadcast domain , minimizing unnecessary traffic. Better Management: Departments (HR, Sales, IT, etc.) can be grouped into different VLANs without changing physical cabling . Requires VLAN Tagging (802.1Q): VLAN information is carried between switches using 802.1Q trunking . VLAN Benefits: Improved security by isolating sensitive systems  Reduced broadcast traffic and better performance Smaller broadcast domains mean less unnecessary traffic and bandwidth saved.. Easy to troubleshoot.  Trunk can carry traffic for up to 4094 VLAN IDs ( ie 4094 subinterfaces ). . Complete Flow PC1 (No Tag) | ...
Read more

🌐 NAT (Network Address Translation)

Image
  🌐 NAT (Network Address Translation) 🧠 Top 6 Key Points Translates Private IPs to Public IPs: NAT converts internal (private) IP addresses into a single or multiple public IPs so that devices inside a LAN can access the Internet. Conserves Public IP Addresses: NAT allows multiple internal hosts to share one public IP, saving global address space. Improves Security: Internal IPs remain hidden from the outside world, reducing attack exposure. Types of NAT: Static NAT: One-to-one mapping (internal ↔ public).  ( Server) Dynamic NAT: Many-to-many mapping (pool of public IPs).  (  PAT (NAT Overload): Many-to-one mapping (most common).  Configured on Routers: NAT runs on routers at the boundary between private and public networks , translating IPs for outbound/inbound traffic. NAT Type Used Today 6 Common Use Static NAT ✅ Yes  (limited use 7 Publishing internal servers with a dedicated public IP Dynamic NAT ⚠️ Rarely L...
Read more

🛰️ OSPF (Open Shortest Path First)

  🛰️ OSPF (Open Shortest Path First) 🧠 Top 5 Key Points about OSPF Link-State Protocol → OSPF shares detailed information about network topology (not just hop count). Metric: Uses cost , calculated based on bandwidth (higher bandwidth = lower cost). Fast Convergence: Quickly detects and adapts to network changes. Supports VLSM & CIDR: Fully classless , allowing subnet flexibility. Area-Based Design: Supports hierarchical networks (Area 0 = Backbone, others connect to it). ⚙️ Additional Notes Works at Layer 3 (Network Layer) of the OSI model. Uses Dijkstra’s SPF (Shortest Path First) algorithm. Multicast addresses: 224.0.0.5 → All OSPF routers 224.0.0.6 → Designated Router (DR) and Backup DR OSPF uses Link-State Advertisements (LSAs) to exchange topology information. Each LSA type has a specific purpose. Here's a practical explanation of LSA Types 1–7 . 1. Type 1 – Router LSA Generated by: Every OSPF router Flooded within...
Read more