IP telephone network design
* For the IP phone components (such as cisco IP phone, cisco CallManager, Cisco IP Softphone Client, IP Gateway, etc.) to achieve Qos classification, marking and congestion management. Qos to VoIP traffic is set to high priority, and giving priority to high-priority transmission queue of traffic.

* VoIP communications will be in exile in a separate VLAN. In order to deploy a Cisco IP phone separate VLAN, a simple method is to use the voice VLAN (auxiliary VLAN).

* Consider the use of power line (inline power) to the Cisco IP phone power supply. Cisco IP telephone calls from the switch or power supply line.

* Physical cable to verify whether or not to support IP phones. IP telephony and VoIP solutions require at least a Category 5 cable cable.

Vo IP Phone Recommended characteristics

1. Qos

VoIP traffic on the delay and jitter (changes in packet delay), there are strict requirements. To meet the requirements of IP phones, Cisco used a large number of IP Qos properties, on the traffic classification, queuing, congestion monitoring and traffic shaping and compression protection minimize packet loss, delay and jitter. When network congestion occurs after the match, Qos configured critical applications to give a higher priority of service to the network congestion occurs, the key to reduce the application of the less quality of service.

2. Voice VLAN (auxiliary VLAN)

Cisco IP phones have a port for connecting PC, so a lot of Cisco IP phone configurations cisco IP phone so that a serial PC. As the Cisco IP phones and workstations connected to the same switch interface, the VLAN of the interface by adding, after the Cisco IP phones and workstations will be located in the same VLAN. Cisco switches support a unique functionality in the cisco IOS has been known as the voice VLAN, it will join the Cisco IP and workstations in a different vlan. Through the use of voice VLAN, the port can interface to join the VoIP traffic in the VLAN to another. If you want to use voice VLAN, then only need to configure the switch without the cisco IP phone and additional configuration.

Specific works:

1. Used cisco IP phone connected to the voice VLAN configuration of switches

2. After the link is activated, switch immediately sent to the cisco IP phone cisco Discovery Protocol (CDP) information, which includes typical CDP information, including voice VLAN-ID

Tel 3.cisco IP frames received by CDP, the interpretation of voice VLAN-ID, and began to VoIP traffic with 802.1q tag, and then send it to the voice VLAN.
4. Cisco IP Phone also designated outbound frame marked DSCP (Differentiated Services Code Point, differentiated services code point) and Cos (Class of Service, Service Type) value. Voice VLAN, the port from the PC workstation connected to the station frame, CiscoIP phone does not add a VLAN tag. Therefore remain at the workstation access VLAN.

> Network bandwidth supply

If you would like to design a successful IP telephone network, the right essential to the supply of network bandwidth. All applications (including voice, video and data applications) can not exceed the total link bandwidth of 75% of available bandwidth. Even if the bandwidth of all applications available bandwidth is lower than total demand of 75%, still must use Qos design, however, if the application needs more than 75 percent of available bandwidth, the fire should be increased by the use of chain-link bandwidth higher.

From the traffic point of view, a single IP phone calls by the two flow components.

1. — Voice carrier stream contains the actual voice samples from the RTP (Real-Time Transport Protocol, Real-time Transport Protocol) packet composition

2. Call Control Signaling — from belonging to one of a number of agreements (such as H.323 or MGCP media Gateway Control Protocol, Media Gateway Control Protocol) packets components. Belong to the kind of specific agreement, the endpoint depends on the participation in the call, call control functions including the establishment, maintenance, removal and redirect calls, etc.

VoIP data packets from the link layer 2 header (14 bytes), IP header (20 bytes), User Datagram (UDP) header (8 bytes), RTP header (12 bytes) and voice components load. Reported that the length of the first link with the use of Layer 2 medium to another. VoIP datagram transmission overhead is very important. In addition, the voice sampling rate determines the bit rate. Sampling rate with the speech coding / decoding device to another. The most common encoding / decoding is G.711 and G.729, they use the total bandwidth (including the IP header and link layer 2 header) are 87.2kbit / s and 31.2kbit / s. In proposing solutions, IP phones must be used, including all headers, including the total rate to calculate the number of concurrent voice calls for some time the amount of bandwidth needed, especially for low-speed WAN interface.

Voice VLAN Configuration

Configured access VLAN and voice VLAN

1) into the overall pattern of configure terminal

2) Configure VLAN and voice VLAN access
No. vlan vlan

3) configuration interface and voice VLAN access VLAN interface for Layer 3 routing

interface vlan vlan No.

ip address address mask

no shut

Configured access VLAN and voice VLAN interface

1) into the interface mode interface interface

2) will be added to the access VLAN interface

VLAN access switchport access vlan No.

3) added to the voice VLAN interface

switchport voice vlan vlan number | dot1p | none | untagged

vlan number: in the specified VLAN in the forwarding of all voice traffic. Default under, IP phones transmit voice traffic through the 802.1Q priority of 5 and tag VLAN, for the from / to the Cisco IP phone traffic.

Dot1p: The IP phone traffic, use the 802.1p priority tags, to other traffic, use the local default vlan (vlan0) transponders. The CDP does not support 3rd party IP phones, regular use of this configuration

None: disable the voice VLAN feature, cisco IP phones will be in accordance with its own configuration to send non-tagged frames

Untagged: Cisco IP phone does not explicitly use the frame tag
4) Enable portfast feature
spanning-tree portfast

n configuration corresponding Qos

1) Enable Qos
mls qos

2) configuration interface, voice frames will be mapped to the value of Cos outbound queue

wrr-queue cos-map 4 5

wrr-queue cos-map 3 4 6 7
3) will be configured to queue 4, the strict priority queue

priority-queue out

Category Qos configuration interface
1) into the interface mode interface interface

2) configure the type of interface based on the classification of the kind of trust

mls qos trust cos | dscp

Verify:
Switch # show interface f0 / 4 switchport
Name: Fa0 / 4

Switchport: Enabled

Administrative Mode: dynamic desirable
Operational Mode: down

Administrative Trunking Encapsulation: dot1q

Negotiation of Trunking: On

Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)

Voice VLAN: dot1p

Administrative private-vlan host-association: none

Administrative private-vlan mapping: none

Administrative private-vlan trunk native VLAN: none

Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none

Administrative private-vlan trunk private VLANs: none

Operational private-vlan: none

Trunking VLANs Enabled: ALL

Pruning VLANs Enabled: 2-1001
Capture Mode Disabled

Capture VLANs Allowed: ALL

Protected: false

Appliance trust: none

Configure the priority of traffic

1) into the overall pattern of configure terminal

2) to enter the interface mode ineterface interface
3) set the IP phone access port from the data received at the priority

switchport priority extend [cos value | trust]

cos value: the highest value for 0-7,7

trust: confidence-building configuration telephone access port of the data received from the PC-priority
Case:

Switch (config) # inter f0 / 4

Switch (config-if) # switchport priority extend cos 7

Switch # show interface f0 / 4 switchport

Name: Fa0 / 4
Switchport: Enabled

Administrative Mode: dynamic desirable

Operational Mode: down

Administrative Trunking Encapsulation: dot1q

Negotiation of Trunking: On
Access Mode VLAN: 1 (default)

Trunking Native Mode VLAN: 1 (default)

Voice VLAN: dot1p

Administrative private-vlan host-association: none
Administrative private-vlan mapping: none

Administrative private-vlan trunk native VLAN: none

Administrative private-vlan trunk encapsulation: dot1q

Administrative private-vlan trunk normal VLANs: none

Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none

Trunking VLANs Enabled: ALL

Pruning VLANs Enabled: 2-1001

Capture Mode Disabled
Capture VLANs Allowed: ALL

Protected: false

Appliance trust: 7

————————————————– ————————–

Switch (config-if) # switchport priority extend trust

Switch # show interf f0 / 4 switch

Name: Fa0 / 4
Switchport: Enabled

Administrative Mode: dynamic desirable

Operational Mode: down

Administrative Trunking Encapsulation: dot1q
Negotiation of Trunking: On

Access Mode VLAN: 1 (default)

Trunking Native Mode VLAN: 1 (default)

Voice VLAN: dot1p
Administrative private-vlan host-association: none

Administrative private-vlan mapping: none

Administrative private-vlan trunk native VLAN: none

Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none

Administrative private-vlan trunk private VLANs: none

Operational private-vlan: none

Trunking VLANs Enabled: ALL

Pruning VLANs Enabled: 2-1001
Capture Mode Disabled

Capture VLANs Allowed: ALL

Protected: false
Appliance trust: trusted

————————————————– ————–
Switch # show running interfa f0 / 4

Building configuration …

Current configuration: 139 bytes
!

interface FastEthernet0 / 4

switchport voice vlan dot1p

switchport priority extend trust

mls qos trust cos

spanning-tree portfast

end