CCNP Exam Prep Tips and Must Knows about Voice and Video in Campus Networks

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What You Need to Know about Voice and Video in Campus Networks

Components of Unified Communications

  • IP phones
  • Call Agent
      • Provides call control for IP phones, CAC, bandwidth control and management, and address translation
  • Voice Gateways to PSTN
    • Provides translation between VoIP and non-VoIP networks
  • Application Server (voice mail)
  • Conference station (voice and video)
  • IP network (router and switches)

 

Characteristics of Voice and Data
Voice

      • Smooth
      • Benign
      • Drop sensitive
      • Delay sensitive
      • UDP priority

Data

      • Smooth or bursty
      • Benign or greedy
      • Drop insensitive
      • Delay insensitive
      • TCP retransmits

 

Video Applications

      • Cisco TelePresence
      •  IP surveillance
      • Digital media systems

Characteristics of video applications:

      • Most are interactive
      • Video contains voice as well
      • Requires a connection with little delay to prevent jitter
      • Requires a high-bandwidth connection depending on the video resolution
      • Peer-to-peer traffic
      • Video endpoints are connected to the access layer

 

Meeting the Requirements of Voice

      • Provisioning, management and security – Voice VLAN and DHCP
      • Bandwidth, Delay/Jitter and Packet Loss – QoS
      • Power – Power over Ethernet (PoE) and UPS
      • Availability – High availability and redundancy

Voice Implementation Steps
Voice VLAN

      • Configure voice VLANs on the access ports
      • Add voice VLANs to the trunks
      • Configure subnets for voice VLANs
      • Configure DHCP for voice subnets
      • Enable routing for voice VLANs

PoE

      • Provide PoE on access switches
      • Implement UPS

QoS

      • Implement auto QoS for VoIP

High Availability

      • Optimize the topology, routing and redundancy

 

Voice VLAN Configuration

      • Switch(config)# interface fa0/4
      • Switch(config-if)# switchport mode access
      • Switch(config-if)# switchport access VLAN 10
      • Switch(config-if)# switchport voice VLAN 110
      • Switch(config-if)# spanning-tree PortFast
      • Switch(config-if)# spanning-tree bpduguard enable
      • Switch(config-if)# cdp enable

Power over Ethernet 802.3af
Two incompatible PoE detection methods

      • Cisco in-line power (2000)
      • IEEE 802.3af standard (2003)
      • TEC supports up to 15.4 W per port

New Cisco devices support both PoE methods

      • Cisco Aironet 1131AG and 1242AG access points
      • Cisco catalyst switches: 3560, 3750, 4500, and 6500 line cards okay
      • Routers with PoE: Cisco 1812 integrated services router, switch modules

Automatic detection is supported; no configuration is required

Test plan for IP phones

      • Does the IP phone receive an IP address?
      • Does the PC behind the IP phone receive an IP address?
      • Does the IP phone register with Cisco Unified Communications Manager or Cisco Unified Communications Manager Express?
      • Can you place a call to another IP phone?

High availability for VoIP and video

      • Traditional telephony networks claim 99.999% uptime
      • Real-time video applications are very sensitive to packet loss and delay
      • Data networks was considered reliability and availability requirements when incorporating voice and video
      • Methods to improve reliability and availability include:
        • Redundant hardware
        • Redundant links
        • UPS
        • Proactive network management

         

        Building of voice, video and data campus network
        Access layer

            • Auto phone detection
            • Power over Ethernet
            • QOS: scheduling, trust boundary, and classification
            • Fast convergence

        Distribution layer

            • High availability, redundancy, and fast convergence
            • Policy enforcement
            • QoS: scheduling, trust boundary, and classification

        Core

            • High availability, redundancy, and fast convergence
            • QoS: scheduling and trust boundary

         

        Recommended Practices: QoS

            • Deployed in an end-to-end configuration
            • Ensures mission-critical apps are not impacted by links or transmit queue congestion
            • Enforces QoS policies at aggregation and great transition points
            • Uses multiple queues with configurable admission criteria and scheduling

         

        Layer 2 Marking: 802.p, CoS

            • The IEEE 802.1P space User Priority Field is also called class of service (CoS)
            • Different types of traffic are assigned different CoS values
            • CoS 6 and 7 are reserved for network use

         

        Layer 3 marking: IP Precedence, DSCP
        IPv4

            • The three most significant bits of the ToS byte are all IP precedence
            • Other gifts for unused

        DiffServ

            • The six most significant bits of the ToS byte are called Diff Serv code point (DSCP)
            • DSCP is backward compatible with IP precedence
            • The remaining two bits are used for flow control

         

        Voice VLAN configuration

            • Switch(config)# mls qos
            • Switch(config)# interface fastethernet 0/1
            • Switch(config-if)# switchport mode access
            • Switch(config-if)# switchport access vlan 10
            • Switch(config-if)# switchport voice vlan 110
            • Switch(config-if)#mls qos trust cos
            • Switch(config-if)# mls qos trust device cisco-phone

         

        Make sure you can configure:

            • Voice vlan
            • QoS for voice

         

        Make sure you are familiar with:

            • show power inline
            • show mls qos interface [fa0/1]
            • auto qos

         

        Understand:

          • Trust boundaries for IP telephony
          • Voice implantation plan
          • Voice test plan
          • Voice campus network – implementations at Access, Distribution and Core
          • Recommendations practices for QoS
          • High availability for voice and video

        CCNP Exam Prep Tips and Must Knows Series

        • CCNP Exam Prep Tips and Must Knows about Voice and Video in Campus Networks
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