Campus Network Overview

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.

100Base
-
FX downlinks

Cisco

Catalyst

5000

Catalyst 1924

Catalyst 1924

Catalyst 1924

Catalyst 1924

Catalyst 1924

MDF

ATM OC3c


FORE

ASX
-
1000


Cisco

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
-
T

to wall portal

MSAP

xDSL

T1/FR

LMDS

Modem

Pool

N.W.V

VT ATM Backbone (since 1996)

OC3c ATM (155 Mbit/s)

OC12c ATM (622 Mbit/s)

SHA

FORE

ASX
-
1000

OWE

FORE

ASX
-
1000

HIL

FORE

ASX
-
1000

ISB

Cisco

7507

Internet

Internet2

ISB

FORE

ASX
-
1000

BUR

FORE

ASX
-
1000

CAS

FORE

ASX
-
1000

ISB

Cisco

7507

CAS

Cisco

7507

OWE

Cisco

7507

SHA

Cisco

7507

BUR

Cisco

7507

HIL

Cisco

7507

ISB

Cisco

7507

ISB

Catalyst

5500

HIL

Catalyst

5000

BUR

Catalyst

5500

SHA

Catalyst

5500

OWE

Catalyst

5000

CAS

Catalyst

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

Cisco

Catalyst

5000

Type IV Building Network

Cisco

Catalyst

6509

Catalyst 1924

Catalyst 1924

Catalyst 1924

Catalyst 1924

Catalyst 1924

MDF

2 x 100Base
-
FX

100Base
-
FX downlinks

10Base
-
T

to wall portal

•
10/100 to the desktop

•
High capacity building
concentrator switch
.

•
Scalable Gigabit Ethernet building
backbone.

•
Deployed in ACITC

Type V Building Network

Cisco

Catalyst

6509

Catalyst 3524

Catalyst 3524

Catalyst 3524

Catalyst 3524

Catalyst 3524

Catalyst 3524

Catalyst 3524

Catalyst 3524

Cisco

Catalyst

6509

MDF

2 x 1000Base
-
LX

1000Base
-
T4

interswitch links

10/100Base
-
TX

to wall portal

MSAP

xDSL

T1/FR

LMDS

Modem

Pool

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

SHA

Catalyst

6509

OWE

Catalyst

6509

HIL

Catalyst

6509

ISB

Cisco

7507

Internet

Internet2

ISB

Catalyst

6509

BUR

Catalyst

6509

CAS

Catalyst

6509

ISB

Catalyst

6006

ISB

Cisco

7507

CAS

Cisco

7507

Future POS/DPT/ATM OC12c

or 1000Base
-
ZX

VT ATM Backbone (Fall 2000)

N.W.V

VT

Gigabit

Backbone

ATM OC3c multi
-
mode

ATM OC3c single
-
mode

1000Base
-
SX

Internet

Internet2

SHA

ASX
-
200WG

OWE

ASX
-
200WG

BUR

ASX
-
200BX

CAS

ASX
-
200BX

ISB

ASX
-
1000

HIL

ASX
-
200BX

CAS

Cisco

7507

ISB

Cisco

7507

ISB

Cisco

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