Premise: Nortel Networks BayStackswitches and Cisco Catalyst switchesare both widely deployed in enterpriseclass core networks. IT managerswho deploy a variety of Fast Ethernetand Gigabit Ethernet edge switchingdevices in their networks need guar-anteed interoperability of these coreswitches in order to ensure conver-gence of voice, data and video.Central to that is interoperability ofsuch functions as QoS, VLANs andmulticast capabilities.

Nortel Networks commissionedThe Tolly Group to evaluate

the Layer 2 interoperability of theNortel BayStack 425, 470, 460 and5510 switches for enterprise-classedge networks especially key interop-erability features used extensively inconverged networks – QoS (802.1p),VLANs (802.1Q) and IP multicast.Tolly Group engineers put the Bay-Stack 425, 470, 460 and 5510 switchesthrough a battery of tests along withCisco Catalyst 4500 and Catalyst6500 switches to reveal the depth ofinteroperability each switch provides.

The Tolly Group performed sixinteroperability tests with CiscoCatalyst 4500/Catalyst 6500switches. Testing was performed in January 2004.

Nortel NetworksBayStack 425, 470, 460 and 5510 SwitchesLayer 2 Interoperability Evaluation – Convergence Focus

TOLLYG R O U P

T H E

No. 204112 February 2004

Proves interoperability in six tests with Cisco Catalyst 4500and Catalyst 6500 switches in tests of auto-negotiation, LinkAggregation, Gigabit Ethernet uplinks, QoS, VLANs andIGMP snoopingAchieves IEEE 802.1p/Q interoperability with Cisco Catalyst4500 and Catalyst 6500 switchesSupports Link Aggregation with Cisco Catalyst 4500 andCatalyst 6500 switchesProves seamless support of Per VLAN Spanning TreeProtocol with Cisco Catalyst 4500 and Catalyst 6500 switchesExamines IGMP traffic and prevents unwanted data streamsfrom affecting network performance when Cisco Catalyst4500/Catalyst 6500 switches function as IP multicast routers

Test Highlights

© 2004 The Tolly Group Page 1

Cisco Catalyst 6500

Cisco Catalyst 4500

Per VLAN Spanning

Tree Protocol

Key: = Pass

Third-party devices tested

Tests conducted

Auto-negotiation

Link aggregation

IEEE 802.1p/Q

GigabitUplink

IGMP Snooping

Source: The Tolly Group, January 2004 Figure 1

BayStack 425, 470, 460 and 5510 SwitchesLayer 2 Interoperability Evaluation – Convergence Focus

TestSummary

Tests revealed that the quartetof BayStack edge switches testedinteroperate flawlessly withcore Catalyst 4500/Catalyst6500 devices in an enterprisenetwork, ensuring network con-vergence, service convergenceand application convergence.

Test Results

Auto-negotiation of

Ethernet Port

Characteristics

Each pair of switches mustproperly negotiate the highestspeed and duplex settings common to both devices. TheTolly Group tested the auto-negotiation characteristics ofthe Nortel BayStack 425, 470,460 and 5510 switches whencommunicating with the CiscoCatalyst 4500/Catalyst 6500switches. Results show that theBayStack 425, 470, 460 and5510 switches interoperate withthe Cisco switches in the test.(See Figure 1.)

Link Aggregation

Link Aggregation allows two ormore physical ports to functionas a single logical port betweena pair of switches. Each switchpair must communicate over an aggregated link consisting of two full-duplex, Fast Ether-net or Gigabit Ethernet links.The Nortel BayStack 425, 470,460 and 5510 switches passedthe Link Aggregation interoper-ability test with both CiscoCatalyst core switches tested.(See Figure 1.)

The Nortel BayStack 425, 470,460 and 5510 switches’ success-

ful interoperability in the LinkAggregation test means that theswitch can form a trunk linkwith the Cisco Catalyst 4500and Catalyst 6500 switches. Itdoes this by combining smallerchannels into a larger link andtransmitting data over it andthat the Nortel Networks’ Multi-Link Trunks (MLT) – Nortel’sversion of Link Aggregation –interoperates with the CiscoSystems’ EtherChannel – Cisco’sversion of Link Aggregation.

Quality of Service &

VLANs – 802.1p/Q

Each switch pair must demon-strate that when a virtual LAN(VLAN) tag and priority frameis introduced, the switch for-wards the packet without modi-fication to the frame. The TollyGroup tested the NortelNetworks BayStack 425, 470,460 and 5510 switches anddetermined that the switchescan exchange VLAN taggedand priority packets successfullywithout modification with bothof the Cisco Catalyst switchestested. (See Figure 1.)

Gigabit Ethernet

Uplink

As workgroup switched networksconverge with backbone campusnetworks, it is not uncommon toneed a Gigabit Ethernet linkbetween switches from differentvendors. Each pair of switchesmust interoperate across a single,full-duplex Gigabit Ethernet(1000Base-SX or 1000Base-TX) uplink. The Tolly Groupdetermined that the NortelBayStack, 425, 470, 460 and

5510 switches interoperate withboth Catalyst switches testedwhen supporting a GigabitEthernet uplink to the Ciscodevices. (See Figure 1.)

Per VLAN Spanning

Tree (PVST)

The goal of the Per VLANSpanning Tree (Cisco propri-etary PVST+) tests was todemonstrate the capability torecover from a device or linkfailure even though the CiscoCatalyst switches are runningthis proprietary protocol. TheTolly Group determined that theBayStack 425, 460, 470, &5510 switches interoperate withboth Cisco Catalyst 6500 &4500. (See Figure 1.)

IGMP Snooping

This test verifies that the deviceunder test supports the IGMPSnooping properly, when usingCatalyst switches at the core asthe IP multicast routers. Testsdemonstrated that the NortelBayStack 425, 470, 460 and5510 switches sensed IGMPhost membership report fromthe attached stations and set upthe dedicated path in betweenthe requesting stations and theIP multicast routers – in thiscase the Cisco Catalyst 4500/Catalyst 6500. (See Figure 1.)

Analysis

In a world of ever-evolvingstandards and tight budgets, net-work managers searching fornew equipment need to knowthat the switches they purchaseare interoperable with their cur-rent infrastructure. It is impor-

The Tolly Group Nortel Networks BayStack 425, 470, 460 & 5510

© 2004 The Tolly Group Page 2

tant for managers to knowwhich devices can work togeth-er and which devices can main-tain interoperability.

In this series of tests, NortelNetworks proves that theBayStack 425, 470, 460 and5510 switches are viable candi-dates for edge switch deploy-ment. But this test tells just oneside of a multidimensionalapproach to edge switchingtaken by Nortel Networks. Inaddition to its rich display ofinteroperability, NortelNetworks is factoring in adiverse set of Optivity networkmanagement tools to provide

users with fine-grained controlover edge switching and band-width policies that will ensureconvergence at many levels.

Tests show that the NortelBayStack switches tested caninteroperate with CiscoCatalyst core devices to ensurenetwork convergence such thatvoice, data and video are han-dled by a single network proto-col. Tests such as 802.1p/Qdemonstrate Nortel’s commit-ment to service convergence inwhich telephony services anddata applications can share thesame IP network facilities.Meanwhile, other tests, such as

Autonegotiation, Spanning Treeand Gigabit Ethernet Uplinksindicate that the BayStacks canfoster application convergenceby ensuring that the networkcan adapt to changing condi-tions to support applicationrequirements.

© 2004 The Tolly Group Page 3

The Tolly Group Nortel Networks BayStack 425, 470, 460 & 5510

BayStack 425-24TLayer 2 deviceFour physical ports are present, two out of fourcan be simultaneously active, (Qty. 2 SFP GBICshared with Qty. 2 10/100/1000 Base-T)24 10/100-Mbps portsUp to eight in a stackCost-effective closet solution16 Gbps switch fabricStacks with BayStack 420-24T and BayStack 425-24T

BayStack 460-24T-PWRLayer 2 device24 10/100-Mbps ports availableGigabit MDA, expansion moduleUp to eight in a stack802.3af Power over EthernetQuality of Service (QoS)Stacks with BayStack 450-24T, BayStack 460-24T-PWR, BayStack 470 and BayStack BPS

BayStack 470-24T and 470-48TLayer 2 device24 and 48 10/100-Mbps ports availableTwo 1000-Mbps uplink ports (GBIC)

Up to eight in a stackQuality of Service (QoS)Stacks with BayStack 450-24T, BayStack 460-24T-PWR, BayStack 470 and BayStack BPS

BayStack 5510-24T and 5510-48TLayer 2/Layer 3 switchFour physical ports are present, two out of fourcan be simultaneously active, (Qty. 2 SFP GBICshared with Qty. 2 10/100/1000 Base-T)24 and 48 10/100/1000-Mbps ports availableUp to eight in a stackQuality of Service (QoS)Up to 640 Gbps stacking throughput160 Gbps switch fabric; Up to 1.28 Terabit persecond for the stackStacks with BayStack 5510-24T and BayStack5510-48T

For more information contact:Nortel Networks 3500 Carling Ave. Nepean, Ontario K2H 8E9 URL: http://www.nortelnetworks.com*Vendor-supplied information not verified by The Tolly Group

Nortel Networks

BayStack 425,470, 460 and5510

Layer 2Interoperability

Nortel NetworksBayStack 425, 470, 460 and 5510

Product Specifications*

Furthermore, test results alsodemonstrate that the BayStacksare resilient to network outagesby provisioning multiple datapaths from source to destinationand allowing for a re-conver-gence path that reduces theamount of time required for arecovery.

Lastly, while tests did notinclude a formal evaluation ofNortel’s Optivity network management solutions, OptivityNetwork Management System(NMS) provides a unified man-agement, troubleshooting andmonitoring tool for a multi-vendor solutions.

A more cost-effective tool isOptivity Switch Manager (OSM)which provides a centrally man-aged configuration tool with built-in TFTP server for BayStack,Passport, and Alteon switches.

For simple-to-deploy QoS capa-bilities Optivity Policy Services(OPS) provides a single QoSprovisioning management toolfor all Nortel BayStack andPassport switches that allowsfor centrally managed QoS policies across the network.

Moreover, Nortel’s QoS supportis very granular – meaningNortel offers support for up toeight traffic queues versus justfour for Cisco and policy con-figuration is not as rigid as“off/on” but can be provisionedby a variety of managementoptions SSHv2, SNMPv3,Device Manager GUI for con-figuration control, QoS wizards,OSM & Optivity integration,and common Command lineinterface (CLI).

It is clear that any of the Norteledge network capabilities testedcan be managed to ensure edgepolicy decisions are handledexpediently and with minimalhassle.

In summary, Nortel is demon-strating that its BayStackswitches are highly interoperablewith Cisco core switches whilealso providing a suite of man-agement facilities that can bedeployed to meet a diverse setof user requirements. With theseinteroperability proof points and management facilities,Nortel can make a convincingcase that BayStack is a soundchoice for managing the edge of enterprise networks.

Test

Configuration

and Methodology

For interoperability tests, TollyGroup engineers connected theBayStack 425 Switch softwarever. 3.0.0.46, the BayStack 460Switch software ver. 3.0.3.8, theBayStack 470 Switch softwarever. 3.0.3.8 and the BayStack5515 Switch software ver. 3.0.1to the Cisco Systems, Inc.Catalyst 4500 software ver.12.1(13)EW and the CiscoSystems, Inc. Catalyst 6500software ver. 12.1(8b)EX3.

For Layer 2 auto-negotiationtests, the tested BayStackswitch connected on one sidevia Category 5 UTP cable to anIxia Communications 1600Tchassis outfitted withLM100TX and LM1000TXS4cards to generate test traffic.The BayStacks under test also

connected to the Cisco Catalyst4500/Catalyst 6500 representingcore network switches. Engi-neers recorded the speed andthe duplex setting reported byeach device in the test and thenverified that the reported speedand duplex type were correct bygenerating a 256-byte bidirec-tional stream of traffic of 100Mbps between the two devicesand verified that no data was lost.

Testers measured Link Aggre-gation using MLT for NortelBayStack switches andEtherChannel for the CiscoCatalyst switches, which alsointeroperate with the IEEE802.3ad specification. For thisround of testing, 12 FastEthernet Ixia ports were con-nected to one BayStack switch(Switch ‘A’) and the other 12Fast Ethernet ports connected toa second BayStack switch undertest (Switch ‘B’). A pair ofGigabit Ethernet links connect-ed between the switch ‘A’ andthe Cisco Catalyst 4500 andanother pair of Gigabit Ethernetlinks connected between theswitch ‘B’ and Cisco Catalyst6500. The Cisco Catalyst 4500and the Cisco Catalyst 6500were connected with each otherusing a pair of Gigabit Ethernetlinks. (See Figure 2.)

Testers configured each Ixiaport to generate multiplestreams with random source anddestination MAC and IPaddresses at the rate of 100Mbps. Engineers directed 12ports of traffic from the Ixia toSwitch A and 12 ports of theIxia traffic was directed toSwitch B. Both switches passedthe traffic across the aggregated

The Tolly Group Nortel Networks BayStack 425, 470, 460 & 5510

© 2004 The Tolly Group Page 4

links. As a result, 1.2 Gbps oftraffic transited from Switch Ato Switch B across the CiscoCatalyst switch infrastructureand 1.2 Gbps from Switch B toSwitch A. (Therefore, the totalaggregate traffic was 2.4 Gbps.(Note: the maximum aggregatefull-duplex link capacity usingtwo Gigabit Ethernet links is 4Gbps.) Testers considered theswitches would ‘pass’ the testwhen bidirectional traffic wentthrough the aggregated linkwithout noticeable frame loss.Also, the aggregate link had toshare traffic evenly. Otherwise,there is no true meaning of load balancing and increasingcarrying capacity.

The Gigabit Uplink test wasconducted in a similar manner,however, it utilized a singleGigabit Ethernet link for uplinktesting instead of a pair of con-nections. (Note: The scope ofthe Link Aggregation test was toprove the switch capable ofLink Aggregation of more than2 Gbps of full-duplex traffic; itwas not a performance test.)

For tests of 802.1p/Q, eachswitch pair under test was con-figured for 802.1p/Q. Engineersthen generated a stream of 68-byte, VLAN tag and priorityframes destined for the remoteswitch’s private network acrossthe Cisco Catalyst switch infrastructure via an IxiaCommunications IxExplorer.The Ixia IxExplorer’s packetcapture tool validated the stateof the packet arriving at thefinal destination all the wayacross the Nortel edge switchnetworks and Cisco core net-works. The IxExplorer counted

all frames received maintainingthe 802.1p/Q VLAN tags. Thetest was then repeated runningin the reverse direction, initiatingtraffic from the original receivingnetwork.

For interoperability tests of PerVLAN Spanning Tree, engi-neers configured each of thetwo BayStack switches to havetwo links cross-connecting thetwo Cisco core switches (onelink configured as the primaryand the other as the secondary)and one Ixia port on each of the two BayStack edge switch-es. The links for Nortel edgedevices need to be configured tomatch the VLAN ID used bytagged PVST+ BPDUs fromCisco's switches; this allowsNortel switches to forward theCisco proprietary BPDUs inorder for its switches to detect apotential loop properly. The testsconfirmed Nortel BayStackswitches can interoperate withCisco core switches.

The engineers initiated asequence of frames via Ixia and verified the traffic to passalong the primary path withoutframe loss. The active path was then failed and then thedestination Ixia port was moni-tored for the number of secondsbefore the network reconvergedand the traffic transited the secondary link. Engineers alsotested the reverse scenario byplugging the primary cablesback to the switch port.BayStack edge switches pairingwith Cisco Catalyst core switchesrecovers from a device or link failure using Spanning Tree. Therecovery time will vary depend-ing on the size of the Spanning

Tree network as well as thetimer's configuration. In orderto achieve sub-second fail over,other mechanisms such asNortel's Split Multilink trunkingcould be used as an alternativeto Spanning Tree which wasproven to inter-operate with othervendors. The same test was donewith different VLAN ID's to vali-date the BayStack's inter-operatewith Cisco switches with anynumber of Per VLAN SpanningTree instances created on thecore switches.

For IGMP Snooping tests, engineers configured the CiscoCatalyst 4500/Catalyst 6500 as IP Multicast routers supportingProtocol Independent Multicast(PIM) Dense Mode (DM) andconnected the Cisco Catalystswitch to the BayStack switchsupporting IGMP Snooping.Also, engineers attached the one Ixia port to the IP Multicastrouter as a streaming server and two Ixia ports to theBayStack switch as streamingclients. Ixia ScriptMate reportedthe devices that joined the IPmulticast group and generatedthe test traffic for the verifica-tion. The Ixia ScriptMate alsoreported the number of lostframes and the number ofleaked frames. The multicasttraffic was generated at the rate of 50 Mbps from the multi-cast source. The Tolly Groupalso used the Finisar SurveyorAnalyzer to check if there stillwas any multicast frame leak-age in the BayStack switch.

The Tolly Group Nortel Networks BayStack 425, 470, 460 & 5510

© 2004 The Tolly Group Page 5

The Tolly Group gratefully acknowledges the providers of test equipment used in this project. Vendor Product Web address Finisar Surveyor 5.0 http://www.agilent.comIxia Communications 1600T http://www.ixiacom.comIxia Communications LM100TX http://www.ixiacom.comIxia Communications LM1000TXS4 http://www.ixiacom.comIxia Communications IxExplorer v. 3.7 http://www.ixiacom.comIxia Communications ScriptMate v. 4.0 http://www.ixiacom.com

Tolly Group ServicesWith more than 15 years of testing experience of leading-edge network technologies, The Tolly Group employstime-proven test methodologies and fair testing principlesto benchmark products and services with the highestdegree of accuracy. Plus, unlike narrowly focused testingshops, The Tolly Group combines its vast technologyknowledge with focused marketing services to help clientsbetter position product benchmarks for maximum expo-sure. The company offers an unparalleled array of reportsand services including: Test Summaries, Tolly Verifieds,performance certification programs, educational Webcasts,white paper production, proof-of-concept testing, networkplanning, industry studies, end-user services, strategic consulting and integrated marketing services. Learn more

about The Tolly Group services by calling(561) 391-5610, or send E-mail tosales@tolly.com.

Project ProfileSponsor: Nortel Networks Inc.Document number: 204112Product class: Layer 2 switchesProducts under test:

Nortel Networks BayStack 425-24T Switch SW ver. 3.0.0.46Nortel Networks BayStack 460-24T-PWR Switch SWver. 3.0.3.8Nortel Networks BayStack 470-24T, 470-48T Switch SW ver. 3.0.3.8Nortel Networks BayStack 5510-24T, 5510-48T Switch SW ver. 3.0.1Cisco Systems, Inc. Catalyst 4500 Series switch SW IOSver. 12.1(13)EWCisco Systems, Inc. Catalyst 6500 Series switch SW IOSver. 12.1(8b)EX3

Testing window: January 2004

For more information on this document, or other services offeredby The Tolly Group, visit our World Wide Web site athttp://www.tolly.com, send E-mail to sales@tolly.com, call (561) 391-5610.

Information technology is an area of rapid growth and constant change. The Tolly Group conducts engineering-caliber testing in an effort to providethe internetworking industry with valuable information on current products and technology. While great care is taken to assure utmost accuracy, mis-takes can occur. In no event shall The Tolly Group be liable for damages of any kind including direct, indirect, special, incidental, and consequentialdamages which may result from the use of information contained in this document. All trademarks are the property of their respective owners.

The Tolly Group doc. 204112 rev. clk 17 Mar 04

The Tolly Group Nortel Networks BayStack 425, 470, 460 & 5510

© 2004 The Tolly Group Page 6

For info on the Fair Testing Charter, visit:http://www.tolly.com/Corporate/FTC.aspx

Ixia 1600T

Nortel BayStack 425-24T

Nortel BayStack 5510-48T

Nortel BayStack 470-48T

Nortel BayStack 460-24T PWR

1

2

3

4

Catalyst4507

5

6

7

FANSTATUS

MAX 15.4W/PORT

STATUS

WS-X4548-G B-RJ45V

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

M ULTI-SPEEDG IGABIT ETHER NET

SW ITC HING MO DULE

48-P ORT10/100/1000 BAS E T

IN -LIN E POWER

3231

3029

2827

2625

2423

2221

2019

1817

4847

4645

4443

4241

4039

3837

3635

3433

1615

1413

1211

109

87

65

43

21

32313029282726252423222120191817 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

WS-X4013+ SUPERVISOR ENGINE II PLUS

STATUS

UPLINK 1

LIN K AC TIV E

UPLINK 2

AC TIV ELIN K ACTIVE 1% 100%

UTILIZATION

C ON SOLE

LINK

10/100

MG T

FLASH

EJECT

R ESET

MAX 15.4W/PORT

STATUS

WS-X4548-G B-RJ45V

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

M ULTI-SPEEDG IGABIT ETHER NET

SW ITC HING MO DULE

48-P ORT10/100/1000 BAS E T

IN -LIN E POWER

3231

3029

2827

2625

2423

2221

2019

1817

4847

4645

4443

4241

4039

3837

3635

3433

1615

1413

1211

109

87

65

43

21

32313029282726252423222120191817 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

Catalyst 4 9 1 2 G

STATUS

1 2 3 4 5 6 7 8 9 10 1% 100%

UTILIZATION

11 12 PS1 RPSU

CONSOLE 10 BAST

INPUT OK

FAN OK

OUTPUT FAIL

2800ACV

220-240 V~

16 A

50/60 Hz

Switch m ust be in off "O" position to Install/Rem ove power supply.Fastener must be fully enaged prior to operating power supply.

INPUT

INPUT OK

FAN OK

OUTPUT FAIL

2800ACV

220-240 V~

16 A

50/60 Hz

Switch m ust be in off "O" position to Install/Rem ove power supply.Fastener must be fully enaged prior to operating power supply.

INPUT

Cisco Catalyst 4500

FANSTATUS

1

2

3

4

5

6

7

8

9

Power Supply 1 Power Supply 2

Catalyst 6500 SERIES

WS-X4013+ SUPERVISO R ENGINE II PLUS

STATUS

U PLINK 1

LINK AC TIVE

UPLINK 2

AC TIVELINK ACTIV E 1% 100%

U TILIZA TION

CO NSO LE

LIN K

10/100

M G T

FLASH

EJEC T

RES ET

M AX 15.4W/PORT

STATU S

WS -X4548-G B-R J45V

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

M ULTI-SP EEDG IGAB IT E THER NET

SW ITCHIN G M O DULE

48-PO RT10/100/1000 BASE T

IN -LIN E PO WER

3231

3029

2827

2625

2423

2221

2019

1817

4847

4645

4443

4241

4039

3837

3635

3433

1615

1413

1211

109

87

65

43

21

32313029282726252423222120191817 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

M AX 15.4W/PORT

STATU S

WS -X4548-G B-R J45V

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

M ULTI-SP EEDG IGAB IT E THER NET

SW ITCHIN G M O DULE

48-PO RT10/100/1000 BASE T

IN -LIN E PO WER

3231

3029

2827

2625

2423

2221

2019

1817

4847

4645

4443

4241

4039

3837

3635

3433

1615

1413

1211

109

87

65

43

21

32313029282726252423222120191817 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

16 - 8 A1800 W

60/50 Hz

INPUTOK

FANOK

OUTPUTFAIL

RUNINSTALL

100-240 V~16 - 8 A1800 W

60/50 Hz

INPUTOK

FANOK

OUTPUTFAIL

RUNINSTALL

100-240 V~

Cisco Catalyst 6500

Optivity Policy Services(OPS)

Test BedDiagram

Source: The Tolly Group, January 2004 Figure 2