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R&S C1 : Introduction to Switched Networks (1.1 LAN Design (1.1.1…
R&S C1 : Introduction to Switched Networks
1.1 LAN Design
1.1.1 Converged Networks
1.1.1.1 Growing Complexity of Networks
1.1.1.2 Elements of
a Converged Network
1 physical network
1.1.1.3 Cisco Borderless Networks
1.1.1.4 Hierarchy
in the Borderless
Switched Network
Hierarchical
role of each device
Modularity
continuous network expansion
Resiliency
network always on
Flexibility
using all network resources
1.1.1.5 Access, Distribution,
and Core Layers
Distribution Layer
middle layer,
Access Layer
traffic enter,exita
Core Layer
network backbone
fault isolation
high-speed backbone connectivity
EXTENDED STAR
scalable, cost-effective,
efficient physical cable layout design
TWO-TIER CAMPUS
NETWORK DESIGN
smaller campus location
distribution and core layer together
1.1.1.6 Activity
1.1.2 Switched
Networks
1.1.2.1 Role of
Switched Networks
Quality of Service
Additional security
Support for wireless
networking and connectivity
Support for new technologies,
such as IP telephony
and mobility services
1.1.2.2 Form Factors
Fixed Configuration Switches
no extra ports for example
Modular Configuration
Switches
more multiple line cards
Stackable Configuration Switches
add multipe together
fault tolerance / bandwidth availability critical
modular to costly
Business considerations
Port density : amount of ports it need to support
Cost : number and speed of interfaces
Power : PoE (power over internet)
Reliability : continuous network access
Frame Buffers : ability to store frames
Scalability : number of users on network
1.1.2.3 Activity - Identify Switch Hardware
1.2 The Switched Environment
1.2.1 Frame Forwarding
1.2.1.1 Switching as a General Concept in Networking and Telecommunications
PSTN
public switched telephone network
1.2.1.2 Dynamically Populating a Switch MAC Address Table
add source mac address
1.1. if already in: reset aging timer
if destination mac address not in table: send to all ports
destination device replies
switch enter source mac address and port number in address table
1.2.1.3 Switch Forwarding Methods
ASIC
reduce packet-handling
time within device
application-specific-
integrated circuits
1.2.1.4 Store-and-Forward Switching
Error checking
check FCS
frame free of physical
and data-link errors
frame dropped if fcs is false
automatic buffering
support any mix of Ethernet speeds
1.2.1.5 Cut-Through Switching
rapid frame forwarding
sends whenever destination
MAC address received
can forward errored frames
can use bandwidth to send invalid frames
fragment free
wait for collision window
not devided
better than cut-through
no latency
good for high-performance computing (HPC)
1.2.1.6 Activity - Frame Forwarding Methods
1.2.1.7 Activity - Switch it
1.2.2 Switching Domains
1.2.2.1 Collision Domains
devices within one switch , when they try to communicate at the same time, a collision occurs
1.2.2.2Broadcast Domains
broadcast frame is send to
all devices connected to the switch,
included other switches,
which will send on their half the
frame to all their connected devices
Broadcast domain increased
1.2.2.3 Alleviating Network Congestion
High port density
large frame buffers
ability to store more received
frames because of loaded ports it can be usefull
port speed
possible to support multiple port speeds
fast internal switching
high performance > fast internal bus / shared memory
low per-port cost
high-port density at lower cost : fewer users per segment : increasing the average available bandwidth per user
1.2.2.4 Activity µ
Summary