procurve voip lldp qos

8/10/2019 ProCurve VoIP Lldp Qos

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ProCurve VoIP, LLDP-MED, and QoSPosted byJeff Brownell

LLDP-MED

Link Layer Discovery Protocol (LLDP) is an ieee standard protocol defined in 802.1AB. It's usedto discover directly attached devices (switches, routers, IP Phones, etc.). LLDP advertisements areencapsulated in LLDP Data Units (LLDPDU) via Type Length Values (TLV). The standard defines twotypes of TLVs: Standard and Optional.

LLDP devices must support the advertisement of Standard TLVs (Chassis ID, Port ID, TTL, etc.),and may also include optional TLVs'. These optional TLVs' are where vendor specific advertisementswould be defined (model, firmware, PoE, QoS, etc.).

VLANsTypically IP Phones have a single port that supports both a PC and the phone vlan. Generally the dataVLAN is left untagged and the voice VLAN is tagged. There are three ways that the IP telephone canlearn its voice VLAN:

1) Manually set it on the phone.

2) DHCP optionsThe phone sends DHCP requests over the data VLAN, and the DHCP server offerwill include vendor specific DHCP options including the voice VLAN.

3) Use a discovery protocolLLDP-MED or CDPv2. Here, the phone will discover the voice VLANfrom the switch.

On Provision switches using LLDP-MED, you must first enable lldp globally and then set theparameter voice in the vlan context for the switch to accept LLDP-MED TLV advertisements.

hp(config)# lldp run

hp(config)# vlan 100hp(vlan-100) name "VOICE"hp(vlan-100) tagged hp(vlan-100) voice Use lldp-med TLVs sent from the phone

hp(vlan-100) exit

QoSThere are two commonly used QoS marking methods; ClassofService (CoS) at Layer 2 andDifferentiated Service Code Point (DSCP) at Layer 3.CoS marking (also known as 802.1p) has 8 levels, numbered 07 which map to 8 priority queueson the output (egress) of each Ethernet port. The CoS marking can be set in tagged frames onlysince the priority field (802.1p) is part of the VLAN tag. Untagged frames are placed in the CoSlevel 0 priority queue (or normal).

On most HP switches the CoS values 07 map to priority queues like so:

[1] [2] [0] [3] [4] [5] [6] [7]
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Therefore, a CoS 0 priority will be mapped to hardware output queue Q3 and take precedenceover frames marked 1 & 2. Most HP edge switches have 8 output queues and is configurable tohave 4 or 2 if desired.

hp(config)# qos queue-config2-queues Set the number of egress queues for each port.

4-queues Set the number of egress queues for each port.8-queues Set the number of egress queues for each port.

hp(config)# qos queue-config 4-queuesThis command will modify the current running configuration,execute 'write memory' to replace the startup configuration,and then reboot.

Egress queues will be configured as follows:4-queues

Do you want to save current configuration [y/n/^C]?

The default mapping of CoS values to output queues on an HP edge switch looks like this:

In voice deployments, generally the Ethernet switch port is configured to support 2 VLANs, one forvoice and one for data. LLDP is enabled on these Ethernet ports and can be configured to advertisevoice VLAN ID and QoS information using the Network Policy LLDP TLV.

Generally I set prioritization queues for voice, video, and switch control plane traffic on edge switchesas:

Priority Traffic7 Control plane6 Routing5 IP voice4 IP video

3 Voice signaling0 Normal Data1 http, bulk transfer, etc.2 http, bulk transfer, etc.

The priority can either be set on the interface or the vlan. If you set the priority at the interface level,the switch will not be able to distinguish normal data traffic from voice.

QoS can also be used to prioritize traffic globally on TCP/UDP port based traffic. This can be used onsoft phones since the switch doesnt know the difference between normal data traffic and soft phonevoice traffic.

VLAN based prioritization applies to the 802.1p flag in a tagged (trunked) packet. Therefore it will only

prioritize tagged traffic for the vlan it is set in. As such, the untagged vlan doesnt have the 802.1pheader and therefore will remain at normal priority (priority 0).
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Trust vs. Non-Trust QoS Modeling

Trust ModelIn TRUST model, the edge switch accepts (or trusts) the phones QoS markings without modifying the

priority. Procurve switches default setting is trust.

If the frame is routed, the MAC header is stripped before routing the packet to its destination. To keepthe priority across routers use DSCP. To prevent users over-riding priority settings, use strict priorityprovisioning with CoS and/or DSCP as well.

Non-Trusted ModelIn most environments the trust model is fine. Otherwise you can strictly provision COS priority perinterface or vlan. You can also globally prioritize traffic based on TCP/UDP port numbers. Additionallyyou can create a Classifier base QoS Policy to prioritize traffic.

LLDP and QoS exampleThe following example shows the use of LLDP-MED and strict QoS provisioning to modify the defaultsettings. The VoIP VLAN is set through LLDP-MED and qos is set via DSCP:

Enable LLDP globally2920(config)# lldp run

Enable Differential Code Services proritization2920(config)# qos type-of-service diff-services

Create and configure the telephony VLAN where all of the telephony equipment will run

2920(config)# vlan 102920 (vlan-10)# name VOICE_SIGNALING

2920 (vlan-10)# qos dscp 011000 (802.1p pri 3)

Create and configure the voice VLAN2920(config)# vlan 202920 (vlan-20)# name VOICE


2920 (vlan-20)# voice Accept lldp-med TLV's

Create and configure the VIDEO VLAN2920(config)# vlan 302920 (vlan-30)# name VIDEO


Create and configure the data VLAN.2920(config)# vlan 402920 (vlan-40)# name DATA

2920 (vlan-40)# qos dscp 010010 (802.1p pri 0 - Normal)

Advanced QoS on ProvisionIn some cases you may want to reduce the number of hardware queues to 4 or 2. This would allow

resources that are by default shared across 8 queues to be shared across 4 or 2 queues. Example:

hp(config)# qos queue-config 4-queues
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This changes the switch to only use 4 queues (needs a reboot to take affect). You use the show qosqueue to verify

hp# show qos queue-config802.1p

Queue Pri Memory %----- --- --------1 12 102 0,3 703 45 104 67 10

The amount of packet buffer memory allocated to the queues is pre-defined and not user configurable.

However, the user can change the amount of Guaranteed Minimum Bandwidth (GMB) allocated toeach queue. The default GMB queue settings are:

These defaults can be viewed with the following command:

hp# show bandwidth output 1-5

Outbound Guaranteed Minimum Bandwidth %

Port Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8------ --- --- --- --- --- --- --- ---1 2 3 30 10 10 10 15 202 2 3 30 10 10 10 15 203 2 3 30 10 10 10 15 20

4 2 3 30 10 10 10 15 205 2 3 30 10 10 10 15 20

These GMB values can be changed on interfaces. This command is for interface 1 through to 5:

hp(config)# int 1-5 bandwidth-min output 2 3 30 10 20 15 10 10

TThis is for 8-queues, if you had the switch set to 4-queues then then only 4 GMB values is used. Thepercentages allowed to the queues should add up to 100%. In the above example GMB for Q5 (video)and Q6 (voice) pulls bandwidth from the default settings of Q7 (routing traffic) and Q8 (net mgmt).

hp(config)# show bandwidth output 1-5

Outbound Guaranteed Minimum Bandwidth %
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Port Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8------ --- --- --- --- --- --- --- ---1 2 3 30 10 20 15 10 102 2 3 30 10 20 15 10 103 2 3 30 10 20 15 10 104 2 3 30 10 20 15 10 10

5 2 3 30 10 20 15 10 10

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