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Extreme Networks Data Sheet

Enterprise-Grade Voice Solution

High-Speed Cross Subnet

Roaming

Summit WM series controllers offer

scalable, voice-grade performance,

meaning that VoWLAN users can roam

from AP to AP—even across subnets—

without experiencing annoying echoes or

dropped connections. When roaming,

client IP addresses do not change as users

move and applications are not affected.

These capabilities are easily added to

existing networks without conﬁguration

changes, topology modiﬁcations or client

software.

Summit WM series controllers are capable

of taking advantage of roaming enhance-

ments based on the 802.11i standard. With

pre-authentication and key caching, users

can quickly move between APs even when

authenticating to centralized network

RADIUS resources. Security is not

compromised with the high-speed

roaming—Summit WM series controllers

generate a unique key only for the APs to

which the client is likely to roam. The

Summit WM system supports PMK caching

and Opportunistic Key caching schemes to

enable faster roaming

End-to-end Mobile QoS

QoS is critical, especially for VoWLAN or

high-priority users. Summit WM control-

lers’ architecture offers end-to-end QoS

from the wireless client to the packet

destination. In addition, QoS is easy to

conﬁgure for different classes of users

through the WM-ADs.

The wireless QoS solution from

Extreme Networks maintains the correct

trafﬁc priority from client to destination.

Over the air, latency-sensitive trafﬁc is

given priority transmit access using either

the SpectraLink Voice Protocol (SVP) or

802.11e Wireless Multimedia (WMM)

priority management. Summit WM control-

lers map the wireless QoS to wired Layer 2

(802.1p) and Layer 3 (DSCP) QoS mark-

ings for upstream and downstream trafﬁc.

In addition, Summit WM20 supports

priority queuing on the egress ports, based

on the trafﬁc stream priority. This way

WM-ADs with mixed trafﬁc (such as voice

and data) can prioritize voice over the other

trafﬁc. It also provides enforcement of

trafﬁc priority across the wired and wireless

networks. Figure 3 shows end-to-end QoS

priority.

Summit WM WLAN solution supports Call

Admission Control (CAC) as per IEEE

802.11e based Trafﬁc Speciﬁcations

(TSPEC). CAC is a trafﬁc management

technique that regulates the number of

calls for better roaming. A client can

request a new voice session with speciﬁc

trafﬁc stream parameters including QoS.

These parameters are part of the TPEC

associated with a session request.

Summit WM can accept or reject the

session request based on the availability of

Today’s enterprise wireless LANs must perform the same tasks with the same expectations for performance and quality as their

wired counterparts. Summit WM series controllers deliver outstanding performance for advanced, latency-sensitive applications

such as VoWLAN.

network resources to deliver the requested

level of service. It also prevents oversub-

scription of network resources that can

result in service degradation and poor voice

quality. It prevents resources from being

oversubscribed in a way that impairs QoS.

In addition to CAC, Summit WM offers QoS

Basis Service Set (QBSS)-based intelligent

roaming to enable clients to make informed

decisions during roaming, based on the

loading factor of an AP. The QBSS load is an

indicator in the Information Element that

represents the percentage of time that the

channel is in use by the AP. A low QBSS

means that an AP is not heavily utilized. A

QoS enabled client will select an appropri-

ate lightly loaded AP before beginning the

TSPEC negotiation.

Automatic Power Save Mode

to Extend Handset Battery Life

To maximize battery life on handheld

devices like a VoWLAN or dual-mode

handsets, Summit WM has implemented a

standards-based (802.11e) Unscheduled

Automatic Power Save Delivery (U-APSD)

mechanism. During a session, a U-APSD

enabled client can go into periodic sleep

mode to save battery power. During this

sleep period, the AP queues up the packets

for the destined client. On wakeup, the

client triggers a request to the AP to deliver

the queued up packets.

Voice

Gateway

Summit WM20

Altitude 350-2

Corporate

Network

Over the Air

• AP and clients

transmit priority

traffic first

• How: SVP or WMM

To the Controller

• AP expedites high priority

traffic to controller

• How: Map WLAN QoS

priority to wired Layer 2

and Layer 3 QoS

To the Destination

• Controller routes traffic

to final destination

• How: Controller maintains

traffic priority on egress

port queues

Figure 3: End-toEnd QoS Priority

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