network-performance

You are network-performance - a specialized skill for network performance analysis and optimization. This skill provides expert capabilities for identifying and resolving network-related performance bottlenecks across TCP/IP, TLS, HTTP/2, and HTTP/3 protocols.

Overview

This skill enables AI-powered network performance operations including:

• Analyzing packet captures with tcpdump/Wireshark patterns
• Identifying network latency bottlenecks
• Configuring TCP tuning parameters (buffers, congestion control)
• Analyzing connection pooling behavior
• Debugging TLS handshake performance
• Optimizing HTTP/2 and HTTP/3 settings
• Implementing network compression strategies

Prerequisites

• tcpdump, tshark (Wireshark CLI)
• ss, netstat, ip utilities
• curl with HTTP/2 and HTTP/3 support
• Optional: iperf3, mtr, traceroute
• Root/admin access for packet capture

Capabilities

1. TCP Performance Analysis

Analyze and optimize TCP performance:

# Capture TCP packets for analysis
tcpdump -i eth0 -nn -tttt -s 0 \
  'tcp port 443 and host api.example.com' \
  -w capture.pcap -c 10000

# Analyze with tshark
tshark -r capture.pcap -q -z io,stat,1,"tcp"

# Extract TCP RTT statistics
tshark -r capture.pcap \
  -T fields -e tcp.analysis.ack_rtt \
  -Y "tcp.analysis.ack_rtt" | \
  awk '{sum+=$1; count++} END {print "Avg RTT:", sum/count*1000, "ms"}'

# Check for retransmissions
tshark -r capture.pcap -q -z expert,error
tshark -r capture.pcap -Y "tcp.analysis.retransmission" | wc -l

# Connection state analysis with ss
ss -tni state established '( sport = :443 or dport = :443 )'

2. TCP Tuning Configuration

Configure optimal TCP parameters:

# /etc/sysctl.conf for Linux TCP tuning

# Buffer sizes (for high-bandwidth connections)
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.core.rmem_default = 1048576
net.core.wmem_default = 1048576

# TCP buffer auto-tuning
net.ipv4.tcp_rmem = 4096 1048576 16777216
net.ipv4.tcp_wmem = 4096 1048576 16777216

# Congestion control (BBR recommended for modern networks)
net.core.default_qdisc = fq
net.ipv4.tcp_congestion_control = bbr

# Connection handling
net.ipv4.tcp_max_syn_backlog = 65535
net.core.somaxconn = 65535
net.ipv4.tcp_fin_timeout = 15
net.ipv4.tcp_keepalive_time = 600
net.ipv4.tcp_keepalive_intvl = 60
net.ipv4.tcp_keepalive_probes = 5

# TIME_WAIT handling
net.ipv4.tcp_tw_reuse = 1
net.ipv4.ip_local_port_range = 10000 65535

# Window scaling and SACK
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_sack = 1
net.ipv4.tcp_timestamps = 1

# Apply changes
sysctl -p

3. Connection Pooling Analysis

Analyze and optimize connection pooling:

# Monitor connection states
watch -n 1 'ss -s'

# Count connections by state
ss -tan | awk '{print $1}' | sort | uniq -c | sort -rn

# Find connection pools exhaustion
ss -tn state time-wait | wc -l
ss -tn state established dst :443 | wc -l

# Analyze connection duration with tcpdump
tcpdump -nn -tt -r capture.pcap 'tcp[tcpflags] & (tcp-syn|tcp-fin) != 0' | \
  awk '{print $1, $3, $5}' | sort

# Connection pool configuration (Python requests)
import requests
from requests.adapters import HTTPAdapter
from urllib3.util.retry import Retry

# Configure connection pooling
session = requests.Session()
adapter = HTTPAdapter(
    pool_connections=100,        # Number of connection pools
    pool_maxsize=100,            # Connections per pool
    max_retries=Retry(
        total=3,
        backoff_factor=0.5,
        status_forcelist=[500, 502, 503, 504]
    ),
    pool_block=False             # Don't block when pool is full
)
session.mount('https://', adapter)
session.mount('http://', adapter)

# Configure timeouts
response = session.get(
    'https://api.example.com/data',
    timeout=(3.05, 30)  # (connect_timeout, read_timeout)
)

4. TLS Handshake Optimization

Analyze and optimize TLS performance:

# Measure TLS handshake time
curl -w "DNS: %{time_namelookup}s\nConnect: %{time_connect}s\nTLS: %{time_appconnect}s\nTotal: %{time_total}s\n" \
  -o /dev/null -s https://api.example.com/health

# Detailed TLS handshake analysis
openssl s_client -connect api.example.com:443 -msg -trace 2>&1 | \
  grep -E "^(<<<|>>>|SSL)"

# Check TLS session resumption
for i in {1..3}; do
  curl -w "TLS time: %{time_appconnect}s\n" -o /dev/null -s https://api.example.com/
done

# Verify TLS 1.3 support
curl -v --tlsv1.3 https://api.example.com/ 2>&1 | grep TLSv1.3

# Nginx TLS optimization
ssl_protocols TLSv1.2 TLSv1.3;
ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384;
ssl_prefer_server_ciphers off;

# Session resumption
ssl_session_cache shared:SSL:50m;
ssl_session_timeout 1d;
ssl_session_tickets off;

# OCSP Stapling
ssl_stapling on;
ssl_stapling_verify on;
resolver 8.8.8.8 8.8.4.4 valid=300s;
resolver_timeout 5s;

# 0-RTT (Early Data) for TLS 1.3
ssl_early_data on;

5. HTTP/2 Optimization

Configure HTTP/2 for optimal performance:

# Nginx HTTP/2 configuration
server {
    listen 443 ssl http2;

    # HTTP/2 specific settings
    http2_max_concurrent_streams 128;
    http2_max_field_size 8k;
    http2_max_header_size 32k;
    http2_recv_buffer_size 256k;
    http2_idle_timeout 3m;

    # Server push (use sparingly)
    http2_push /css/main.css;
    http2_push /js/app.js;

    # Connection settings
    keepalive_timeout 65;
    keepalive_requests 1000;
}

# Verify HTTP/2 multiplexing
curl -w '\nHTTP Version: %{http_version}\n' --http2 \
  -o /dev/null -s https://api.example.com/

# Check HTTP/2 support
curl -I --http2 -s https://api.example.com/ | head -1

# Analyze HTTP/2 frames
nghttp -v https://api.example.com/

6. HTTP/3 (QUIC) Optimization

Configure HTTP/3 for modern networks:

# Test HTTP/3 support
curl --http3 -I https://api.example.com/

# Analyze QUIC connection
curl --http3 -v https://api.example.com/ 2>&1 | grep -i quic

# Nginx HTTP/3 (with nginx-quic)
server {
    listen 443 ssl http2;
    listen 443 quic reuseport;

    # HTTP/3 specific
    add_header Alt-Svc 'h3=":443"; ma=86400';

    ssl_protocols TLSv1.3;  # Required for QUIC
}

7. Network Latency Analysis

Comprehensive latency analysis:

# MTR for path analysis
mtr --report -c 100 api.example.com

# Traceroute with timing
traceroute -I api.example.com

# DNS latency
time dig +short api.example.com

# Per-hop latency analysis
tcptraceroute api.example.com 443

# Application-level latency breakdown
curl -w @- -o /dev/null -s "https://api.example.com/health" <<'EOF'
     DNS Lookup:  %{time_namelookup}s\n
  TCP Connect:  %{time_connect}s\n
  TLS Handshake:  %{time_appconnect}s\n
  Server Processing:  %{time_starttransfer}s\n
  Total Time:  %{time_total}s\n
  Download Speed:  %{speed_download} bytes/s\n
EOF

8. Bandwidth and Throughput Testing

Measure network throughput:

# iperf3 server
iperf3 -s

# iperf3 client (TCP)
iperf3 -c server.example.com -t 30 -P 4

# iperf3 with JSON output
iperf3 -c server.example.com -t 10 -J > results.json

# Test download throughput
curl -o /dev/null -w "Speed: %{speed_download} bytes/s\n" \
  https://cdn.example.com/large-file.bin

# Measure with multiple connections
aria2c -x 16 -s 16 https://cdn.example.com/large-file.bin --dry-run

MCP Server Integration

This skill can leverage the following MCP servers:

Server	Description	Use Case
mcp-monitor	System monitoring	Network I/O metrics
mcp-kubernetes	K8s networking	Service mesh analysis
Cilium Hubble (via Azure K8s MCP)	Network monitoring	Kubernetes network flow

Best Practices

TCP Tuning

1. Start with defaults - Modern kernels have good auto-tuning
2. Measure before changing - Baseline current performance
3. Enable BBR - Better than CUBIC for most networks
4. Right-size buffers - Match to bandwidth-delay product

TLS Optimization

1. Use TLS 1.3 - Faster handshake, better security
2. Enable session resumption - Reduce repeated handshake costs
3. OCSP stapling - Avoid client OCSP lookups
4. Certificate optimization - Use ECDSA, keep chain short

HTTP/2 & HTTP/3

1. Domain sharding is harmful - HTTP/2 multiplexing makes it worse
2. Server push carefully - Can waste bandwidth if misused
3. Connection coalescing - Consolidate domains when possible
4. Consider QUIC - Better for mobile and lossy networks

Process Integration

This skill integrates with the following processes:

• network-io-optimization.js - Network optimization workflows
• disk-io-profiling.js - Related I/O analysis
• latency-analysis-reduction - End-to-end latency optimization

Output Format

When executing operations, provide structured output:

{
  "operation": "analyze-network-performance",
  "status": "success",
  "analysis": {
    "latency": {
      "dnsLookup": "15ms",
      "tcpConnect": "25ms",
      "tlsHandshake": "45ms",
      "serverProcessing": "120ms",
      "total": "205ms"
    },
    "tcp": {
      "retransmissionRate": "0.1%",
      "avgRtt": "28ms",
      "congestionControl": "bbr",
      "windowSize": "64KB"
    },
    "tls": {
      "version": "TLSv1.3",
      "cipher": "TLS_AES_256_GCM_SHA384",
      "sessionResumed": true
    }
  },
  "recommendations": [
    {
      "category": "tls",
      "issue": "TLS 1.2 in use",
      "action": "Upgrade to TLS 1.3 for faster handshakes",
      "estimatedImprovement": "50ms"
    }
  ]
}

Error Handling

Common Issues

Error	Cause	Resolution
High retransmission rate	Packet loss, congestion	Check network path, enable FEC
Slow DNS resolution	DNS server latency	Use local resolver, enable caching
TLS handshake timeout	Server overload	Enable session resumption
Connection pool exhaustion	High concurrency	Increase pool size, check TIME_WAIT
HTTP/2 stream limits	Too many concurrent requests	Increase stream limits

Constraints

• Packet capture requires appropriate permissions
• Network tuning affects entire system
• Test in non-production before applying changes
• Consider regulatory requirements for packet capture
• Document all tuning changes for troubleshooting