Segment Routing สำหรับ Modern Networks
Segment Routing เป็น Network Architecture ที่ทำให้ Traffic Engineering ง่ายขึ้นมาก ใช้ Segments กำหนดเส้นทาง ไม่ต้อง Maintain State ที่ทุก Node ลด Complexity ของ Network
Technical Debt ใน Network สะสมจาก Manual Configuration, Legacy Protocols และ Quick Fixes การใช้ Segment Routing ร่วมกับ Automation ช่วยลด Technical Debt และทำให้ Network Maintainable
Segment Routing Configuration
# === Segment Routing Configuration ===
# 1. SR-MPLS บน Cisco IOS-XR
# -----------------------------------------------
# Router R1 — Enable Segment Routing
# router isis CORE
# is-type level-2-only
# net 49.0001.0000.0000.0001.00
# address-family ipv4 unicast
# metric-style wide
# segment-routing mpls
# !
# interface Loopback0
# passive
# address-family ipv4 unicast
# prefix-sid index 1
# !
# interface GigabitEthernet0/0/0/0
# point-to-point
# address-family ipv4 unicast
# metric 10
# !
# interface GigabitEthernet0/0/0/1
# point-to-point
# address-family ipv4 unicast
# metric 10
# 2. SR-TE Policy (Traffic Engineering)
# segment-routing
# traffic-eng
# policy SR-POLICY-1
# color 100 end-point ipv4 10.0.0.5
# candidate-paths
# preference 200
# explicit segment-list SL-VIA-R3
# preference 100
# dynamic
# pcep
# metric
# type igp
# !
# !
# segment-list SL-VIA-R3
# index 10 mpls label 16003
# index 20 mpls label 16005
# 3. SRv6 Configuration
# segment-routing
# srv6
# locators
# locator MAIN
# prefix fc00:0:1::/48
# !
# !
# !
# router isis CORE
# address-family ipv6 unicast
# segment-routing srv6
# locator MAIN
# 4. TI-LFA (Topology Independent Loop-Free Alternate)
# router isis CORE
# interface GigabitEthernet0/0/0/0
# address-family ipv4 unicast
# fast-reroute per-prefix
# fast-reroute per-prefix ti-lfa
# 5. Flex-Algo (Flexible Algorithm)
# router isis CORE
# flex-algo 128
# metric-type delay
# advertise-definition
# !
# interface Loopback0
# address-family ipv4 unicast
# prefix-sid algorithm 128 index 101
# Verification Commands
# show isis segment-routing label table
# show segment-routing traffic-eng policy all
# show segment-routing srv6 locator
# show isis fast-reroute summary
# show isis flex-algo 128
echo "Segment Routing configured"
echo " SR-MPLS: Prefix-SID, SR-TE Policy"
echo " SRv6: Locator fc00:0:1::/48"
echo " Protection: TI-LFA"
echo " Optimization: Flex-Algo 128 (delay)"Network Automation สำหรับลด Technical Debt
# network_automation.py — Network Automation ด้วย Nornir
# pip install nornir nornir-netmiko nornir-utils pyyaml jinja2
from dataclasses import dataclass, field
from typing import List, Dict, Optional
import yaml
import json
from datetime import datetime
@dataclass
class NetworkDevice:
hostname: str
ip: str
platform: str # ios, iosxr, junos, eos
role: str # spine, leaf, pe, p, ce
sr_enabled: bool = False
prefix_sid: int = 0
flex_algos: List[int] = field(default_factory=list)
@dataclass
class TechnicalDebtItem:
id: str
category: str # config, protocol, security, documentation
severity: str # critical, high, medium, low
description: str
device: str
remediation: str
created: str = ""
resolved: bool = False
class NetworkDebtManager:
"""จัดการ Technical Debt ใน Network"""
def __init__(self):
self.devices: List[NetworkDevice] = []
self.debt_items: List[TechnicalDebtItem] = []
self.audit_results: Dict = {}
def add_device(self, device: NetworkDevice):
self.devices.append(device)
def audit_device(self, device: NetworkDevice) -> List[TechnicalDebtItem]:
"""ตรวจสอบ Technical Debt บน Device"""
items = []
# Check: SR not enabled
if not device.sr_enabled:
items.append(TechnicalDebtItem(
id=f"TD-{len(self.debt_items)+len(items)+1:04d}",
category="protocol",
severity="high",
description=f"Segment Routing not enabled on {device.hostname}",
device=device.hostname,
remediation="Enable SR-MPLS or SRv6 and assign Prefix-SID",
created=datetime.now().strftime("%Y-%m-%d"),
))
# Check: No Flex-Algo
if device.sr_enabled and not device.flex_algos:
items.append(TechnicalDebtItem(
id=f"TD-{len(self.debt_items)+len(items)+1:04d}",
category="config",
severity="medium",
description=f"No Flex-Algo configured on {device.hostname}",
device=device.hostname,
remediation="Configure Flex-Algo 128 (delay) for latency-sensitive traffic",
created=datetime.now().strftime("%Y-%m-%d"),
))
# Check: Missing TI-LFA
if device.role in ["pe", "p", "spine"]:
items.append(TechnicalDebtItem(
id=f"TD-{len(self.debt_items)+len(items)+1:04d}",
category="config",
severity="high",
description=f"TI-LFA not verified on {device.hostname}",
device=device.hostname,
remediation="Enable TI-LFA on all ISIS/OSPF interfaces",
created=datetime.now().strftime("%Y-%m-%d"),
))
self.debt_items.extend(items)
return items
def audit_all(self):
"""Audit ทุก Devices"""
total_items = []
for device in self.devices:
items = self.audit_device(device)
total_items.extend(items)
self.audit_results = {
"total_devices": len(self.devices),
"total_debt": len(total_items),
"by_severity": {},
"by_category": {},
}
for item in total_items:
self.audit_results["by_severity"][item.severity] = \
self.audit_results["by_severity"].get(item.severity, 0) + 1
self.audit_results["by_category"][item.category] = \
self.audit_results["by_category"].get(item.category, 0) + 1
return self.audit_results
def print_report(self):
"""แสดง Technical Debt Report"""
results = self.audit_all()
print(f"\n{'='*60}")
print(f"Network Technical Debt Report")
print(f"{'='*60}")
print(f" Devices: {results['total_devices']}")
print(f" Total Debt Items: {results['total_debt']}")
print(f"\n By Severity:")
for sev, count in sorted(results["by_severity"].items()):
print(f" {sev:>10}: {count}")
print(f"\n By Category:")
for cat, count in sorted(results["by_category"].items()):
print(f" {cat:>15}: {count}")
print(f"\n Top Items:")
critical = [d for d in self.debt_items if d.severity in ["critical", "high"]]
for item in critical[:10]:
print(f" [{item.severity:>8}] {item.device}: {item.description}")
# ตัวอย่าง
manager = NetworkDebtManager()
devices = [
NetworkDevice("PE1", "10.0.0.1", "iosxr", "pe", True, 1, [128]),
NetworkDevice("PE2", "10.0.0.2", "iosxr", "pe", True, 2, []),
NetworkDevice("P1", "10.0.0.3", "iosxr", "p", True, 3, [128]),
NetworkDevice("P2", "10.0.0.4", "iosxr", "p", False, 0, []),
NetworkDevice("CE1", "10.0.0.5", "ios", "ce", False, 0, []),
]
for d in devices:
manager.add_device(d)
manager.print_report()CI/CD Pipeline สำหรับ Network Changes
# === GitHub Actions — Network CI/CD Pipeline ===
# .github/workflows/network-cicd.yml
name: Network Change Pipeline
on:
pull_request:
paths: ["network/**"]
push:
branches: [main]
paths: ["network/**"]
jobs:
validate:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v4
- uses: actions/setup-python@v5
with:
python-version: "3.11"
- name: Install Dependencies
run: pip install yamllint jsonschema netaddr jinja2
- name: Lint YAML
run: yamllint network/configs/
- name: Validate Schema
run: |
python -c "
import yaml, jsonschema, glob
schema = yaml.safe_load(open('network/schema.yaml'))
for f in glob.glob('network/configs/*.yaml'):
data = yaml.safe_load(open(f))
jsonschema.validate(data, schema)
print(f' OK: {f}')
print('All configs validated')
"
- name: Check Prefix-SID Conflicts
run: |
python -c "
import yaml, glob
sids = {}
for f in glob.glob('network/configs/*.yaml'):
data = yaml.safe_load(open(f))
sid = data.get('prefix_sid', 0)
host = data.get('hostname', f)
if sid in sids:
print(f'CONFLICT: SID {sid} on {host} and {sids[sid]}')
exit(1)
sids[sid] = host
print(f'No SID conflicts ({len(sids)} devices)')
"
test-in-lab:
needs: validate
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v4
- name: Deploy to Lab
run: |
echo "Deploying to lab environment..."
# ansible-playbook -i inventory/lab deploy.yaml
- name: Run Tests
run: |
echo "Running network tests..."
# pytest tests/network/ -v
- name: Verify SR Paths
run: |
echo "Verifying Segment Routing paths..."
# python verify_sr_paths.py --env lab
deploy-production:
needs: test-in-lab
runs-on: ubuntu-latest
if: github.ref == 'refs/heads/main'
environment: production
steps:
- uses: actions/checkout@v4
- name: Deploy to Production
run: |
echo "Deploying to production..."
# ansible-playbook -i inventory/prod deploy.yaml --check
# ansible-playbook -i inventory/prod deploy.yaml
- name: Verify
run: |
echo "Verifying production..."
# python verify_sr_paths.py --env production
- name: Notify
run: |
echo "Network change deployed successfully"Best Practices
- Prefix-SID Planning: วางแผน Prefix-SID Range ล่วงหน้า ใช้ Convention เช่น Node Index = Last Octet
- TI-LFA ทุก Interface: เปิด TI-LFA สำหรับ Sub-50ms Failover โดยไม่ต้อง RSVP-TE
- Flex-Algo: ใช้ Flex-Algo แยก Traffic ตาม Constraint เช่น Delay, Affinity
- IaC สำหรับ Network: เก็บ Config ทั้งหมดใน Git ใช้ Templates + Variables
- Regular Audit: ตรวจสอบ Technical Debt อย่างน้อยทุกไตรมาส
- Lab Testing: ทดสอบทุก Change ใน Lab ก่อน Deploy Production
Segment Routing คืออะไร
Network Architecture ใช้ Segments กำหนดเส้นทาง Packets Stateless ไม่ต้อง Maintain State ทุก Node มี SR-MPLS และ SRv6 ง่ายกว่า RSVP-TE Traditional MPLS
Technical Debt ใน Network คืออะไร
ปัญหาสะสมจาก Quick Fix Legacy Protocols Manual Configuration Documentation ไม่อัพเดท Security Patches ไม่ลง ทำให้ Network ยากดูแลเปลี่ยนแปลง
SRv6 ต่างจาก SR-MPLS อย่างไร
SR-MPLS ใช้ MPLS Labels บน MPLS Data Plane เหมาะ Network ที่มี MPLS SRv6 ใช้ IPv6 Addresses บน IPv6 Data Plane Network Programming มากกว่า ไม่ต้องมี MPLS
วิธีลด Technical Debt ใน Network ทำอย่างไร
ใช้ IaC จัดการ Config Automate ด้วย Ansible/Nornir CI/CD Pipeline Migrate Legacy Protocols Documentation as Code Regular Audit Cleanup ทดสอบใน Lab ก่อน Deploy
สรุป
Segment Routing ทำให้ Traffic Engineering ง่ายขึ้น ลด Complexity ของ Network เมื่อรวมกับ Automation และ CI/CD Pipeline ช่วยลด Technical Debt ใช้ IaC เก็บ Config ใน Git ทดสอบใน Lab ก่อน Deploy TI-LFA สำหรับ Fast Failover Flex-Algo แยก Traffic Regular Audit ทุกไตรมาส
