Network Management (Tools, Netflow, NBAR, IP SLA)

Monitoring and Managing

  • Know your network is doing well.
  • Understand the trends in your network performance.
  • Identify your bottlenecks and propose solutions.
  • Proact – Don’t react.

Phases of optimizations and the tools

  1. Create a baseline – Netflow, NBAR, IP SLA
  2. Optimize Network – QoS, AutoQoS VoIP, AutoQoS Enterprise
  3. Measure / Adjust – Netflow, NBAR, IP SLA, Syslog
  4. Deploy Apps – Netflow, NBAR

Syslogging

Level numberSeverityDescription.
0EmergenciesSystem is unusable.
1AlertImmediate action is needed.
2CriticalCritical conditions.
3ErrorError conditions.
4WarningWarning conditions.
5NotificationNormal but significant conditions.
6InformationalInformational messages only.
7DebuggingDebugging messages only.
  • Key practices:
    • Set the right date / time.
    • Use the same IOS version ( different messages, severity ).
    • Out of Band management ( security , performance ).
    • Centralized logging server.

Netflow

  • https://en.wikipedia.org/wiki/NetFlow
  • Esed for Traffic accounting
  • Heavily used by:
    • Service Providers
      • Network Planning
      • Accounting and Billing
      • Security
      • Traffic Engineering
    • Enterprise Customers
      • Internet Conenction Monitoring
      • User / Application Monitoring
      • Security
  • NetFlow tracks Flows ( Sessions )
    • IP Source Address
    • IP Destination Address
    • Source Port Number
    • Destination Port Number
    • Protocol type ( udp / tcp / etc )
    • Input Interface

NBAR (Network Based Application Recognition) / AutoQoS

    • Cisco NBAR
    • WhitePaper AutoQoS
    • Identifies Applications in traffic flows
    • Inspects layer 2-4 , layer 7 data for supported applications ( around 90 supported )
    • Expandable through IOS Upgrades and PDLMs (Packet Description Language Module)
    • Integrates with QoS mechanics
    • Integrats with SNMP mechanics
  • Starting with NBAR
    • sh ip nbar protocol-discovery stats bit-rate top-n 10
    • Onboard IOS tools allow for top x reporting
    • Gobs of monitoring tools use this data (MRTG, Cacti, Zabbix)
    • Integrates into class-map ( QoS ) and AutoQoS Mechanics

AutoQoS

  • Cisco AutoQoS
  • Comes in two flavours:
    • AutoQoS for VoIP ( Pre-defined policy-map templates)
      • Creates about 40 lines of config
    • AutoQoS for Enterprise ( application sniffing with NBAR )
      • Uses NBAR to identify the key applications
  • Trusted Mode ( Believes existing DSCP )
  • Untrusted Mode ( Leverages NBAR Discovery )

IP SLA

    • Cisco IP SLA
    • Technically:
      • A contract with a service level guarantee
      • In Cisco: A method of measuring service level by sending test traffic.
    • Able to Measure:
      • Network Delay
      • Packet loss
      • Jitter
      • Voice Quality
    • SNMP Reporting also an option.

 

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