campus design eng
TRANSCRIPT
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UTC-N
Overview of Campus NetworksOverview of Campus Networks DesignDesign
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Overview
Read Chapter 1 for further information andexplanations
Much of the information in this chapter will
become clearer throughout the semester as
this chapter is meant to introduce you to someof the topics we will be discussing later
!he design models used in this chapter is not a
template for network design "t should be used
as a foundation for discussion of concepts and
a vehicle for addressing various issues
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Icons
Multilayer Switch with Route Processor
- Don’t let the location of the links into this
icon confuse you. This will become clearer
when we configure this device.
igh-!nd Switch
Router
"orkgrou# Switch
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Traditional Campus Networks
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Traditional Campus Networks
Campus Network
# building or group of buildings connected into one
enterprise network that consists of or more $#Ns
!he company usually owns the physical wires
deployed in the campus
%enerally uses $#N technologies
%enerally deploy a campus design that is optimi&ed
for the fastest functional architecture over existing
wire
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Traditional Campus NetworksNetwork #dministrator Challenges
$#N run effectively and efficiently #vailability and performance impacted by the amount of
bandwidth in the network
'nderstand( implement and manage traffic flow
Current "ssues
)roadcasts* "+ #R+ re,uests
-merging "ssues
Multicast traffic .traffic propagated to a specific group ofusers on a subnet/( video conferencing( multimedia traffic
0ecurity and traffic flow
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#
ollow the 23453 rule( not the 53423
!raditional 53423 rule
6 537 traffic local to subnet( 237 remote
8Remote9 traffic 6 !raffic across the backbone or core to enterprise servers(
"nternet( remote sites( other subnets .more coming/
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$
New 23453 rule
6 237 traffic local to subnet( 537 remote
!raffic moving towards new 23453 rule due to*
6 :eb based computing
6 0ervers consolidation of enterprise and workgroup servers intocentrali&ed server farms due to reduced !CO( security andease of management
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New Campus Model services can be
separated into categories*
6 $ocal
6 Remote
6 -nterprise
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Traditional &outer and 'u( Campus
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)irtual !"N *)!"N+ Tec,nolo-ies
Many of these diagrams have further explanations that
follow Much of this should be review from C"0 15;( but
will also be covered in much more detail later on this
semester Read on your own $ink at end of presentation
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(FYI: Review) One of the technologies developed to
enable campus<wide =$#Ns is =$#N trunking #
=$#N trunk between two $ayer 2 switches allows
traffic from several logical networks to be multiplexed # =$#N trunk between a $ayer 2 switch and a router
allows the router to connect to several logical
networks over a single physical interface "n igure 2(
a =$#N trunk allows server > to talk to all the =$#Nssimultaneously !he yellow lines in igure 1 are "nter<
0witch $ink ."0$/ trunks that carry the pink( purple(
and green =$#Ns
5321, is a =$#N tagging protocol that wasdeveloped to allow =$#N trunking !he =$#N tag is
an integer incorporated into the header of frames
passing between two devices !he tag value allows
the data from multiple =$#Ns to be multiplexed and
demultiplexed
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Traditional Campus./ide )!"N 0esi-n
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(FYI: Review) $ayer 2 switching is used in the access(
distribution( and core layers our workgroups
represented by the colors blue( red( purple( and green
are distributed across several access<layer switchesConnectivity between workgroups is by Router > that
connects to all four =$#Ns $ayer ; switching and
services are concentrated at Router > -nterprise
servers are shown behind the router on different logical
networks indicated by the black lines
!he various =$#N connections to Router > could be
replaced by an "0$ trunk "n either case( Router > is
typically referred to as a ?router on a stick? or a ?one<
armed router? More routers can be used to distribute
the load( and each router attaches to several or all
=$#Ns !raffic between workgroups must traverse the
campus in the source =$#N to a port on the gateway
router( then back out into the destination =$#N
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ultilayer Campus 0esi-n wit, ultilayer witc,in-
*witc, locks+
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(FYI: Review) )ecause $ayer ; switching is used in the
distribution layer of the multilayer model( this is where
many of the characteristic advantages of routing apply
!he distribution layer forms a broadcast boundary so thatbroadcasts don@t pass from a building to the backbone or
vice<versa =alue<added features of the Cisco "O0
software apply at the distribution layer or example( the
distribution<layer switches cache information about Novell
servers and respond to %et Nearest 0erver ,ueries from
Novell clients in the building #nother example is
forwarding Dynamic Aost Configuration +rotocol .DAC+/
messages from mobile "+ workstations to a DAC+ server
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ultilayer odel wit, erver arm
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&edundant ultilayer Campus 0esi-n .0witch )locks/
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witc,in- $ayer 2 0witching
6 0witches based on M#C address
6 8hardware based bridging9 6 edge of the network .new campus mode/
$ayer ; 0witching
6 0witching at $2( hardware<based routing at $;
$ayer B 0witching 6 0witching at $2( hardware<based routing at $;( with
decisions optionally made on $B information .portnumbers/
6 orwarding decisions based on M#C address( "+address( and port numbers
6 Aelp control traffic based on O0 #0"C .#pplication<specific "ntegrated Circuit/
6 0peciali&ed hardware that handles frame forwarding in the
switch
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&outer versus witc,
Router typically performs software<
based packet switching .process of
looking it up first in the routing tables/ 0witch typically performs hardware<
based frame switching .#0"C/
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!ayer 2 witc,in-
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!ayer 3 witc,in- Aardware<based routing
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!ayer 4 witc,in-
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! *ulti.!ayer witc,in-+
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!
CiscoE speciali&ed form of switching androuting( not generic $; routing4$2
switching
Multilayer 0witches can operate at$ayers 2( ;( and B
cannot be performed using our CCN+
lab e,uipment .Catalyst B33F switchesand 2F23 routers/
8route once( switch many9
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!
sometimes referred to as 8route once( switch
many9 .later/
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2#
3.!ayer 'ierarc,ical 0esi-n
odel
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2$
3.!ayer 'ierarc,ical 0esi-n odel
!he devices andconcepts are slightly
different then the ;<layer
model used in 0em G
Routing
Conceptual onlyH
!here will be
contradictions and some
devices may be argued
as one type of device oranother
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Core !ayer "nternet
Remote 0ite
=arious options and
implementations possible
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0ample ;<layer hierarchy" n t e r n e t
C o r e
C o r eC o r e
D i s t r i b u t i o n D i s t r i b u t i o n D i s t r i b u t i o n
# c c e s s# c c e s s
# c c e s s
# c c e s s # c c e s s # c c e s s
# c c e s s
# c c e s s
# c c e s s
# c c e s s
# c c e s s
R e m o t e 0 i t e )
R e m o t e 0 i t e C
# c c e s s
D i s t r i b u t i o n
# c c e s s
# c c e s s
R e m o t e 0 i t e ## c c e s s
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Core !ayer
0witches packets as fast as possible
Considered the backbone of the network
0hould not perform packet manipulation
6 No #C$s 6 No routing .usually/
6 No trunking
6 =$#Ns terminated at distribution device
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0istri(ution !ayer
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0istri(ution
!ayer
!he distribution layer of the network divides the access andcore layers and helps to define and differentiate the core
6 Departmental or workgroup access
6 )roadcast4multicast domain definition
6 =$#N routing 6 #ny media transitions that need to occur
6 0ecurity
6 +acket manipulation occurs here
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"ccess !ayer
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"ccess
!ayer
!he access layer is the point at which local end users are allowed into
the network
6 0hared bandwidth
6 0witched bandwidth
6 M#C<layer filtering or 5321x 6 Microsegmentation
6 Remote users gain network access( =+N
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uildin- locks
Network building blocks can be any one of the
following fundamental campus elements*
6 0witch block 6 Core block
Contributing variables
6 0erver block
6 :#N block
6 Mainframe block
6 "nternet connectivity
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3#
uildin- locks
"nternet )lockcould also be
included
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3$
witc, lock
Consists of both switch and router functions 6 #ccess $ayer .#$/
$2 devices .workgroup switches* Catalyst 2IF3(
2I33( ;G33>$/
6 Distribution $ayer .D$/ $24$; devices .multilayer switches* Catalyst
BG33( FG33/
$2 and separate $; device .Catalyst ;F33>$
with 2533 series router<on<a<stick( etc/
Multiple D$ devices shown for loadbalancing and redundancy !his
may not be the case in many
networks
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4%
AL – Access Layer
6 $2 switches in the wiring closets connect users to
the network at the access layer and provide
dedicated bandwidth to each port DL – Distribution Layer
6 $24$; switch4routers provide broadcast control(
security and connectivity for each switch block
witc, lock
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#$ devices merge into one or more D$ devices
$2 #$ devices have redundant connections to the D$
device to maintain resiliency
6 0panning<!ree +rotocol .0!+/ makes redundant
links possible
witc, lock ."!+rimary
)ackup
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witc, lock
. 0!
!he D$ device*
6 a switch and external router or
6 a multilayer switch .Catalyst BG33/
6 provides $2 and $; services
6 shields the switch block against broadcast storms
.and $2 errors/
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iin- t,e witc, lock
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iin- t,e witc, lock
# switch block is too large if*
6 # traffic bottleneck occurs in the routers at
the distribution layer because of intensiveC+' processing resulting from policy<
based filters
6 )roadcast or multicast traffic slows down
the switches and routers
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Core lock # core is re,uired when there are two or more switch
blocks( otherwise the core or backbone is between
the distribution switch and the perimeter router
!he core block is responsible for transferring cross<
campus traffic without any processor<intensive
operations #ll the traffic going to and from the switch blocks(
server blocks( the "nternet( and the wide<area
network must pass through the core
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Core lock
Core Switches:
Catalyst FG33
Core )lock
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Core lock
!raffic going from one switch block to another also
must travel through the core
!he core handles much more traffic than any otherblock
6 must be able to pass the traffic to and from the
blocks as ,uickly as possible
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4#
Core lock
Cisco FG33 supports*
6 up to ;5B 134133 -thernet
6 1I2 133> ast -thernet 6 5 OC12 #!M
6 up to 1;3 %igabit -thernet ports
6 switching bandwidth up to 2GF %bps 6 scalable multilayer switching up to 1J3
Mpps
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4$
Core lock
)ecause =$#Ns terminate at the distribution device(core links are not trunk links and traffic is routedacross the core
6 core links do not carry multiple =$#Ns per link One or more switches can make up a core subnet
6 a minimum of two devices must be present in thecore to provide redundancy
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Collapsed Core
Distribution and Core $ayer functions performed in the
same device
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Collapsed
Core
consolidation of D$ and core<layer functions into onedevice
6 prevalent in small campus networks each #$ switch has a redundant link to the D$ switch -ach #$ switch may support more than one subnetK
however( all subnets terminate on $; ports on theD$4core switch
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Redundant uplinks provide $2 resiliency between the #$ andD$ switches
6 0panning tree blocks the redundant links to prevent loops
Redundancy is provided at $ayer ; by the dual distributionswitches with Aot 0tandby Router +rotocol .A0R+/(providing transparent default gateway operations for "+.later/
Collapsed
Core
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0ual Core
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0ual
Core
necessary when two or more switch blocks exist andredundant connections are re,uired
provides two e,ual<cost paths and twice the bandwidth -ach core switch carries a symmetrical number of
subnets to the $; function of the D$ device -ach switch block is redundantly linked to both core
switches( allowing for two distinct( e,ual path links
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C,oosin- a Cisco roduct
Lnow particularsH .Number and types ofports/
#ccess $ayer 0witches
6 2IF3( BG33 Distribution $ayer 0witches
6 2IF3%( FG33( ;JG3
Core $ayer 0witches 6 FG33