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Packet Tracer 6Building a VoIP Network (Part 3)

Eric KwokCCIE #43698 (R&S)

Technical Manager, APAC Region

© 2014 Cisco Systems, Inc. All rights reserved.Cisco Networking Academy

Session 3• Why do we need Voice VLAN?

• Access port or trunk port?

• Tagged or not tagged?

© 2014 Cisco Systems, Inc. All rights reserved.Cisco Networking Academy

Why?• Performance (Broadcast domain)

• Manageability (apply policy, QoS, logical group, addressing)

• Independent of Physical Topology (connect phone to any vlan access port)

• Security (boundary between data and voice packet)

Access vlan 10Voice vlan 20

Access vlan 20(voice)

Access vlan 10(data)

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Phone boot up

CDPNative VLAN 10Voice VLAN 20

PoE Power

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Voice VLAN• SW(config-if)# switchport mod access• SW(config-if)# switchport access vlan 10• SW(config-if)# switchport voice vlan 20

Data vlan 10Voice vlan 20

Fa0/1SWPC

Special 802.1Q trunk through CDP

V20 DD

PCP (Priority or CoS)

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SW#sh int switchport

Name: Fa0/1Switchport: EnabledAdministrative Mode: static accessOperational Mode: static accessAdministrative Trunking Encapsulation: dot1qOperational Trunking Encapsulation: nativeNegotiation of Trunking: OffAccess Mode VLAN: 10 (data)Trunking Native Mode VLAN: 1 (default)Voice VLAN: 20Administrative private-vlan host-association: noneAdministrative private-vlan mapping: noneAdministrative private-vlan trunk native VLAN: noneAdministrative private-vlan trunk encapsulation: dot1qAdministrative private-vlan trunk normal VLANs: noneAdministrative private-vlan trunk private VLANs: noneOperational private-vlan: noneTrunking VLANs Enabled: AllPruning VLANs Enabled: 2-1001Capture Mode DisabledCapture VLANs Allowed: ALLProtected: falseUnknown unicast blocked: disabledUnknown multicast blocked: disabledAppliance trust: none

SW#sh int switchport

Name: Fa0/6Switchport: EnabledAdministrative Mode: dynamic autoOperational Mode: downAdministrative Trunking Encapsulation: dot1qOperational Trunking Encapsulation: nativeNegotiation of Trunking: OnAccess Mode VLAN: 1 (default)Trunking Native Mode VLAN: 1 (default)Voice VLAN: noneAdministrative private-vlan host-association: noneAdministrative private-vlan mapping: noneAdministrative private-vlan trunk native VLAN: noneAdministrative private-vlan trunk encapsulation: dot1qAdministrative private-vlan trunk normal VLANs: noneAdministrative private-vlan trunk private VLANs: noneOperational private-vlan: noneTrunking VLANs Enabled: AllPruning VLANs Enabled: 2-1001Capture Mode DisabledCapture VLANs Allowed: ALLProtected: falseUnknown unicast blocked: disabledUnknown multicast blocked: disabled

© 2014 Cisco Systems, Inc. All rights reserved.Cisco Networking Academy

CoS• Ethernet Frame to include QoS

• No field to specific the priority of the frame

• 802.1p task group to work on the traffic classes

• Used in 802.1Q tag (3 bits PCP)

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CoS in Voice Frame

TPCI PCP DEICFI VLAN ID

S.MAC D.MAC Type/Length Payload FCS

S.MAC D.MAC 802.1Q Tag Payload FCSType/

Length

Priority0-7

VLAN0-4095

0x8100

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Lab Setup

SPAN Port

PoE Ports

Cisco 891W 4 Ports PoE

Packet capture

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Phone CDP

Phone sending out CDP

Cisco 7970

Request 10.25W PoE powerMax Power Consumption

Packet capture

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Router (integrated Switch) CDP

Cisco 891 RouterCDP from Router

Native VLAN for Data (untagged)

Voice VLAN (tagged)

Available PoE Power

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Voice VLAN 20

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Priority in VLAN Tag (Voice and Data Frame)

Voice Frame VLAN 20• RTP , Pri 5• SKINNY, Pri 0, 3

7961 Data Frame untaggedNative VLAN

Packet capture

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Data Frame VLAN 10, Pri 0

7970 Data Frame taggedVLAN 10, Pri 0

7961 Data Frame untaggedNative VLAN

© 2014 Cisco Systems, Inc. All rights reserved.Cisco Networking Academy

Let‘s go to Packet Tracer

V20 DD V20 D10

V20

D

Special 802.1Q trunk through CDP

PCP (Priority or CoS)

© 2014 Cisco Systems, Inc. All rights reserved.Cisco Networking Academy

Session 3 Summary• Why do we need Voice VLAN?

• Both data vlan and voice vlan in single port

• Security (diff vlan, policy) and performance (broadcast domain)

• Access port or trunk port?• Special trunk or access port which can handle 802.1Q tag

• Tagged or not tagged?• Voice is tagged with CoS set

• Data could be tagged or not tagged depends on the phone model

• Notes:• Port security, max 2 addresses