10 - IP Telephony Services

Copyright © 2005 Juniper Networks, Inc. Proprietary and Confidential www.juniper.net

4-1

IP Telephony Services

© 2008 Juniper Networks, Inc. All rights reserved. 2

Power over Ethernet

PoE is defined in IEEE 802.3af and facilitates the delivery of regulated power over a standard copper Ethernet network cable

PoE deployments consist of two primary components:•PSE provides power

•PD accepts and utilizes delivered power


Power Classification

IEEE 802.3af has an optional power classification feature that allows a PSE to budget the required power based on the class of the attached devices, significantly reducing power capacity requirements•With power classification: The switch (PSE)

identifies power needs and reserves power for PDs based on class

•Without power classification: The switch (PSE) assigns all PDs the default class (Class 0), which budgets a full 15.4 watts per port


Power Class Definitions

7 watts2

15.4 watts3

4 watts1

Future expansion4

15.4 watts reserved(Actual device requirement can be less)0 (Default)

Maximum Power at Output Port of PSE

Class Number


Power Management

Power management modes include:•Static: Power is deducted from the total power

pool as specified by the user for that interface• Ensures that the maximum power specified for the

interface is always reserved•Dynamic: Power budgeted from the total power

pool for each port matches the actual power consumed

•Class: Power budgeted from the total power pool for each port matches the maximum power for the power class


Power Pool Usage Guidelines

Three power supply capacities:•320 W, 600 W, and 930 W

Any power supply can be installed in any switch model

Installing a higher capacity power supply does not increase the number of PoE ports on the switch

410 W(24 PoE ports

at 15.4 W each)

190 W600 W

740 W(48 PoE ports

at 15.4 W each)

190 W930 W

130 W(8 PoE ports

at 15.4 W each)

190 W320 W

Power Budget for PoE Pool

Switch Consumpt

ion

Power Supply

Capacity


PoE Telemetries

Switch provides telemetries support to keep history of power usage for each PD•Disabled by default; you enable PoE telemetries

through configuration and specify duration and interval values

[edit poe interface interface-name telemetries]user@switch# set ?Possible completions:+ apply-groups Groups from which to inherit configuration data+ apply-groups-except Don't inherit configuration data from these groups disable Disable telemetries duration Duration to continue recording of data (1...24 hours) interval Interval at which data should be recorded (1...30 minutes)


Configuring PoE

[edit poe]user@switch# show interface all | interface {

disable;priority high | low;maximum-power watts;telemetries {

disable;interval minutes;duration hours;

}}

Determines priority for shutdown of individual ports when there is insufficient power for all PoE ports

Allows per-port PoE consumption tracking

Sets maximum amount of power that can be supplied for a port


user@switch> show chassis hardware Hardware inventory:Item Version Part number Serial number DescriptionChassis REV X3 750-021256 BM0207431960 EX4200-24TFPC 0 REV 02A 711-021264 AK0207431816 EX4200-24T, 8 POE…Power Supply 0 REV 01 740-020957 AT0507420091 PS 320W AC…

Use the show chassis hardware command to verify PoE capabilities

•Use the show poe controller command to view PoE power usage and availability

Monitoring PoE (1 of 2)

user@switch> show poe controller

Controller Maximum Power Guard-band ManagementIndex Power Consumption 0 115 W 0W 15W Static


Monitoring PoE (2 of 2)

Use the show poe interface command to verify the operational status of a PoE interface, as well as the actual power being consumed by PDs

•Optionally, verify the same details for an individual interface

user@switch> show poe interface Interface Admin-status Oper-status max-power priority power-consumption Class ge-0/0/1 Enabled ON 15.4W Low 3.5W 0 ge-0/0/3 Enabled OFF 12.0W High 0.0W 0 ge-0/0/5 Enabled OFF 15.4W Low 0.0W 0…

user@switch> show poe interface ge-0/0/3 PoE interface status:PoE interface : ge-0/0/3 Administrative status : Enabled Operational status : OFF Power limit on the interface : 15.4W Priority : High Power consumed : 0.0W Class of power device : 0


Voice VLAN

The voice VLAN feature enables access ports to accept both untagged (data) and tagged (voice) traffic and separate that traffic into different VLANs


Usage Guidelines

When using the voice VLAN feature:•Recommend to configure CoS before enabling

voice VLAN•Enable voice VLAN for switch access ports with IP

phones•Use LLDP-MED to provide voice VLAN ID and

802.1p values to attached IP phones


Configuring a Voice VLAN

[edit ethernet-switching-options]user@switch# showvoip { interface (access-ports | interface-name) { vlan (vlan-name | vid); forwarding-class class; }}

Associates VoIP parameters with all access ports

Associates VoIP parameters with specified access port

Referenced VLAN and forwarding class must be defined locally on switch


Monitoring Voice VLAN

Use the show vlans detail vlan-name command to verify voice VLAN membership, tag, and state information

user@switch> show vlans detail voice VLAN: voice, 802.1Q Tag: 500, Admin state: EnabledDescription: Used for Voice TrafficNumber of interfaces: 3 (Active = 3) Tagged interfaces: ge-0/0/0.0*, ge-0/0/1.0*, ge-0/0/10.0*

* = Active


Link Layer Discovery Protocol

LLDP, as defined in IEEE 802.1ab, is a Layer 2 neighbor discovery protocol that allows network devices to advertise their identity and capabilities

LLDP-enabled devices are called LLDP agents•LLDP agents exchange LLDPDUs• Information learned from neighbors is stored in a

database• Database entries are refreshed periodically

LLDP frames use TLV tuples•LLDP defines a set of mandatory and optional TLVs•LLDP frames are constrained to the local link


LLDPDU Frame Format

LLDP multicast address: 01-80-C2-00-00-0E

Chassis IDTLV

M

Port IDTLV

M

Time to LiveTLV

M

OptionalTLV

OptionalTLV

End of LLDPDU TLV

M

…

M = Mandatory TLV—required for all LLDPDUs


LLDP Updates

LLDP update considerations:•Periodic updates are sent at regular intervals

• Default is 30 seconds; valid range is 5 to 32768 seconds•Triggered updates are sent when local value

changes • Triggered updates conform to 1 per second limit

•Updates are sent as unsecure, one-way advertisements

• LLDP is stateless and offers no authentication


LLDP Transmit Agent

Transmit agent sends periodic and triggered updates•TTL TLV (txTTL) mechanism determines the length of

time information remains valid on the receiver:• msgTxInterval (default of 30 seconds) x msgTxHold (default of

4 seconds)• By default, messages are sent with a default TTL value of 120

sec• If information is not refreshed before TTL expires, it is discarded

Transmit agent notifies neighbor of state changes•Final shutdown LLDPDU is sent with chassis ID, port ID,

TTL TLV field set to 0, and end-of-LLDPDU TLV set• If the transmit agent fails to send shutdown TLV before

the interface goes down, LLDP is maintained until TTL age timer expires

Chassis IDTLVM

Port IDTLVM

Time to LiveTLVM

OptionalTLV

OptionalTLV

End of LLDPDU TLV

M

…


LLDP Receiver Agent

Receiver stores information in a neighbor database•Neighbor database information is accessible by

SNMP•Database is updated to ensure data accuracy

Receiver maintains statistic counters for each interface; these statistics include:•Frames received•Frames with errors•Unknown TLVs


What Is LLDP-MED?

LLDP-MED is an extension to LLDP developed by TIA (ANSI/TIA-1057) to support interoperability and enhance discovery between VoIP endpoint devices and other networking devices

LLDP-MED devices are categorized into three classes:•Class 1: All devices requiring base LLDP discovery service•Class 2: Any device with IP media capabilities

• Examples include voice and media gateways, and conference bridges

•Class 3: Any device used for end-user IP communications• Examples include IP phones and PC-based softphones


LLDP-MED Usage

LLDP-MED can be used for the following:•Network policy discovery

• Allows a switch to deliver VLAN and CoS settings to an IP phone

•Power negotiation• Allows a switch and IP phone to negotiate power

requirements and offerings•Inventory management

• Allows a management system to retrieve system information from endpoint devices

•Location discovery• Identifies the location of IP phones based on the switch

port; primary usage is for emergency services


LLDP and LLDP-MED Interaction

LLDP and LLDP-MED interaction details:•All mandatory LLDP TLVs are advertised in

LLDPDUs as soon as LLDP is enabled•All optional LLDP and LLDP-MED TLVs are enabled

by default•LLDP-MED TLVs are sent only after detecting a MED

deviceLL

DP-M

EDLL

DP

LLDP-M

ED

1. Interface starts advertising base LLDP TLVs (non-LLDP-MED)

2. LLDP-MED frame sent by neighbor

3. Agent toggles to LLDP-MED


LLDP-MED and 802.1X

LLDP-MED and 802.1X considerations:•When 802.1X is enabled, LLDP frames are not

transmitted or received until the port is authenticated

•An IP phone and PC connected to the same switch port can be authenticated separately (multiple supplicant mode) and can receive different VLAN assignments and policies for data and voice

• If only the IP phone or the PC is 802.1X capable, use the single supplicant mode


LLDP and LLDP-MED Example (1 of 4)



I’m

a V

oIP

Gat

eway

I’m

an

IP

Pho

ne

I’m

a

switch

I’m a switchI’m

a

switch

I’m a PC

I’m a switch

I’m a switch

I’m a PC

I’m

a

switch

I’m an IP Phone



xxxx Switchge-0/0/3

………

xxxxIP phonege-0/0/1

xxxxPCge-0/0/2

xxxxGatewayge-0/0/0

InformationDevicePort

xxxx PC/Serverge-0/0/3

………


xxxxPC/

Serverge-0/0/2

xxxxSwitchge-0/0/0


I’m

a

VoI

P

Gat

eway

I’m a switch

I’m

an

IP

Pho

ne

I’m a PC

I’m

a

switch

I’m

a

switch

I’m a switch

I’m a PC

I’m

a

switch

I’m a switch

I’m an IP Phone



xxxx Switchge-0/0/3

………


xxxxPCge-0/0/2

xxxxGatewayge-0/0/0


ManagementApplication

xxxx PC/Serverge-0/0/3

………


xxxxPC/

Serverge-0/0/2

xxxxSwitchge-0/0/0


SNMP

SNMP

I’m

a V

oIP

Gat

eway

I’m a switch

I’m

an

IP

Pho

ne

I’m a PC

I’m

a

switch

I’m

a

switch

I’m a switch

I’m a PC

I’m

a

switch

I’m a switch

I’m an IP Phone


Configuring LLDP and LLDP-MED

[edit protocols]user@switch# show lldp { disable; advertisement-interval seconds; hold-multiplier number; interface [all | interface-name] { disable; }}lldp-med { disable; interface (all | interface-name){ disable; } }}

Determines TTL value sent to neighbor devices

Disables protocol on referenced interface (suggested on untrusted boundaries)


Monitoring LLDP and LLDP-MED

Use the following key commands to monitor LLDP:•Verify LLDP status:

user@switch> show lldp detail

•View learned neighbor information:

user@switch> show lldp neighbors

•Check local LLDP details:

user@switch> show lldp local-info

•View LLDP statistics and counters:

user@switch> show lldp statistics

10 - IP Telephony Services

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