Campus Network Overview

Carl Harris

Associate Director, Research and Development

Communications Network Services

Virginia Tech

What is CNS?

• Communications Network Services provides the following services to Virginia Tech faculty, staff, and students– traditional telephone and voice-mail

– cable television (mostly residence halls)

– IP/IPX/AppleTalk network layer and below• Exception: DNS and DHCP

• Provide services on Blacksburg campus and at graduate centers around the state.

Basic Link Layer Services

• Basic Ethernet portal service– Switched 10Base-T (10 Mbit/s)

– Some switched 100Base-TX (100 Mbit/s), but very expensive.

• Dial-in modem pool with ~1,200 56K modems.• MSAP provides campus backbone access to local

ISPs.– Ethernet in apartment complexes

• ATM portal service for specialized applications (e.g. videoconferencing used in distance learning programs)

Network Layer Architecture

• IP routing– Within our autonomous system (AS):

• OSPF plus some static routes

– Extending beyond our (AS): • BGP4+ (a.k.a. MBGP) plus some static routes

• In the modem pool:EIGRP (Cisco proprietary): fast convergence, low overhead, few knobs. Low CPU cost despite lots of link state changes.

– Coming soon:• Multiprotocol Label Switching (MPLS, a.k.a. tag switching) to

support certain kinds of policy routing

• Packet prioritization and custom queuing disciplines to support apps with strict latency and loss requirements.

Network Layer Architecture

• IP multicast routing– Within our AS:

• Protocol Independent Multicast, Sparse Mode (PIM-SM) between routers.

• Internet Group Management Protocol (IGMPv2) manages multicast group membership to control distribution to hosts.

– Extending beyond our AS:• PIM-SM

• MBGP (multiprotocol, not multicast)

• Multicast Source Discovery Protocol (MSDP)

• A few legacy DVMRP tunnels

Network Layer Architecture

• IPX routing: IPX RIP, NLSP (similar to OSPF)• AppleTalk routing: who cares?

Layer 1 and 2 Architecture

• Primary switching facilities are located in:– Andrews Information Systems Building

– Cassell Coliseum

– Burruss Hall

– Hillcrest Hall

– Owens Hall

– Shanks Hall

• Use fiber-optics to interconnect switching facilities and to fan out to building backbones.

Layer 1 and 2 Architecture

• ATM backbone used as a “substrate” on which to build network layer services.– LAN Emulation (LANE)

• Routers connect to ATM backbone and use LANE to establish virtual connections to each building subnet. LANE also used to interconnect the routers to form a network layer backbone.

• Ethernet switches with LANE capability used in building backbones, ATM connection to campus backbone.

10

0B

ase

-FX

do

wn

links

CiscoCatalyst

5000

Catalyst 1924

Catalyst 1924

Catalyst 1924

Catalyst 1924

Catalyst 1924

MDF

ATM OC3cFORE

ASX-1000Cisco 7507

• Ethernet edge switches go in wiring closets located throughout the building

• LANE connects the router (Cisco 7507) to the primary building switch (Catalyst 5000) via the ATM backbone switch.

Type III Building Network

10Base-Tto wall portal

MSAP

xDSL

T1/FR

LMDS

ModemPool

N.W.V

VT ATM Backbone (since 1996)

OC3c ATM (155 Mbit/s)

OC12c ATM (622 Mbit/s)

SHAFORE

ASX-1000

OWEFORE

ASX-1000

HILFORE

ASX-1000

ISBCisco 7507

Internet

Internet2

ISBFORE

ASX-1000

BURFORE

ASX-1000

CASFORE

ASX-1000

ISBCisco 7507

CASCisco 7507

OWECisco 7507

SHACisco 7507

BURCisco 7507

HILCisco 7507

ISBCisco 7507

ISBCatalyst

5500

HILCatalyst

5000

BURCatalyst

5500

SHACatalyst

5500

OWECatalyst

5000

CASCatalyst

5000

What Now?

• Need low cost 10/100Base-TX portal service• Need to provide greater resiliency, lower latency,

more bandwidth, and packet switching with differentiated QoS for next-generation applications– university administrators using desktop

videoconferencing over IP

– telephone services (voice-over-IP)

– bandwidth killer applications (e.g. Napster)

• Need architecture consist with high-bit-rate multicast (e.g. streaming HDTV via multicast).

• 2 x 100Base-FX building feed, no more ATM

• Simpler model.

• Low cost conversion

• Scalable building feed

CiscoCatalyst

5000

Type IV Building Network

CiscoCatalyst

6509

Catalyst 1924

Catalyst 1924

Catalyst 1924

Catalyst 1924

Catalyst 1924

MDF

2 x 100Base-FX

10

0B

ase

-FX

do

wn

links

10Base-Tto wall portal

• 10/100 to the desktop

• High capacity building

concentrator switch.• Scalable Gigabit Ethernet building

backbone.

• Deployed in ACITC

Type V Building Network

CiscoCatalyst

6509

Catalyst 3524

Catalyst 3524

Catalyst 3524

Catalyst 3524

Catalyst 3524

Catalyst 3524

Catalyst 3524

Catalyst 3524

CiscoCatalyst

6509

MDF

2 x 1000Base-LX

10

00

Ba

se-S

X d

ow

nli n

ks

1000Base-T4 interswitch links

10/100Base-TXto wall portal

MSAP

xDSL

T1/FR

LMDS

ModemPool

VT ATM

Backbone

N.W.V

VT Gigabit Backbone (Fall 2000)

1 x 1000Base-SX

1 x 1000Base-LX

2 x 1000Base-LX

ATM OC3c

1 x 100Base-FX/TX SHACatalyst

6509

OWECatalyst

6509

HILCatalyst

6509

ISBCisco 7507

Internet

Internet2

ISBCatalyst

6509

BURCatalyst

6509

CASCatalyst

6509

ISBCatalyst

6006

ISBCisco 7507

CASCisco 7507

Future POS/DPT/ATM OC12cor 1000Base-ZX

VT ATM Backbone (Fall 2000)

N.W.VVT

GigabitBackbone

ATM OC3c multi-mode

ATM OC3c single-mode

1000Base-SX

Internet

Internet2

SHAASX-200WG

OWEASX-200WG

BURASX-200BX

CASASX-200BX

ISBASX-1000

HILASX-200BX

CASCisco 7507

ISBCisco 7507

ISBCisco 7507

Net.Work.Virginia

• Provides ATM services throughout Virginia to K-12 schools, institutions of higher education, and state agencies– low cost access with level pricing statewide

• OC3c (155 Mbit/s), ~ $150,000/annum

• DS3 (45 Mbit/s), ~$60,000/annum

• DS1 (1.5 Mbit/s), ~12,000/annum

– provides Internet access services, as well as supporting a wealth of ATM-based services (intranet, videoconferening, PSTN toll bypass, etc).

– provides access to Internet2 backbones (Abilene, vBNS)

For More Information

• rdweb.cns.vt.edu• www.networkvirginia.net• www.internet2.edu• www.abilene.iu.edu

Contact Info

Carl Harris

ceharris@vt.edu