NetworkBasics

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Introduction to

Networking Technologies

Stefan Karsten

Technical Consultant

e
-
mail: karst02@cai.com

Agenda


RMON


VLAN


Frame Relay


ATM

RMON


Remote Monitoring Management Information
Base (RMON MIB) was developed by a
working group of the Internet Engineering
Task Force (IETF) for network monitoring


It uses SNMP and its standard MIB design to
provide multivendor interoperability between
monitoring products and management stations

RMON


RMON MIB software agents can be located
on a variety of devices


Network interconnects such as bridges, routers,
or hubs;


dedicated or non
-
dedicated hosts


customized platforms specifically designed as
network management instruments

RMON


RMON MIB is organized into nine groups
for Ethernet (RFC 1271) and ten groups for
Token Ring (RFC 1513)



Enhancements through RMON2
(RFC 2074,RFC 2021)



RMON Ethernet groups


Statistics


Statistics about packets, octets, broadcasts, and
multicasts on a local segment


Packet size distribution


Error counters for collisions, undersized
packets, fragments, CRC, jabbers and oversized
packets

RMON Ethernet groups


History


Historical view of the statistics in the Statistical
group except packet size distribution. Memory
consuming


Host Table


Hosts statistics of packets sent and received,
octets set and received, broadcasts, multicasts
and error packets sent

RMON Ethernet groups


Host Top N


Extends the Host Table by providing sorted
hosts statistics of the top N nodes sent over the
last 24 hours


Traffic Matrix


Shows the amount of traffic and number or
errors between pair of nodes

RMON Ethernet groups


Alarms


Setting Thresholds and sampling intervals to
generate events on any counter maintained by
the agent


Filters


Fills packet capture buffer with packets that
match filters installed by the user

RMON Ethernet groups


Packet Capture


Includes the capability for users to create a
multiple number of capture buffers and to
control when to wrap or stop capturing


Events


Entries created in the monitor log or SNMP
traps send from the agent to the management
station on Alarms of the Event group

RMON Token Ring groups



Host Group, Filter Group,Matrix Group


as defined for Ethernet


Mac
-
Layer Statistics


collects information from Mac Layer, including
error reports for the ring and ring utilization of
the Mac Layer.


Promiscuous Statistics


collects utilization statistics from data packets
collected promiscuously







Waldbusser
[Page 4]



RFC 1513 Token Ring Extensions to
RMON MIB September 1993




3.2. The Token Ring History Groups




The Token Ring History Groups contain
historical utilization and



error statistics. The statistics are broken
down into two groups,



the Token Ring Mac
-
Layer History Group
and the Token Ring Promiscuous



History Group. The Token Ring Mac
-
Layer History Group collects



information from Mac Layer, including
error reports for the ring and



ring utilization of the Mac Layer. The
Token Ring Promiscuous



History Group collects utilization
statistics from data packets



collected promiscuously.



3.3. The Token Ring Ring Station Group




The Token Ring Ring Station Group
contains statistics and status



information associated with each Token
Ring station on the local



ring. In addition, this group provides
status information for each



ring being monitored.



3.4. The Token Ring Ring Station Order
Group




The Token Ring Ring Station Order
Group provides the order of the



stations on monitored rings.



3.5. The Token Ring Ring Station Config
Group




The Token Ring Ring Station Config
Group manages token ring stations



through active means. Any station on a
monitored ring may be removed



or have configuration information
downloaded from it.



3.6. The Token Ring Source Routing
Group

RMON Token Ring groups


Station


contains statistics and status information
associated with each Token Ring station on the
local ring


Station Order


provides the order of the stations on monitored
rings

RMON Token Ring groups


Station Order


provides the order of the stations on monitored
rings


Ring Station Config


manages token ring stations through active
means. Any station on a monitored ring may
be removedor have configuration information
downloaded from it

RMON Token Ring groups


Source Routing


contains utilization statistics derived from
source routing information optionally present in
token ring packets


Most networks consists of a simple,
hierarchical arrangement


Routers allowed communication between
networks when necessary


Traditional routers are slow, complicated
and expensive

Traditional Fully Routed Network

Traditional Fully Routed Network

PCs

Server

Hub

PCs

Server

Hub

PCs

Server

Hub

PCs

Server

Hub

PCs

Server

Hub

Router


Switches spearheaded the next evolution of
network structure


Providing dedicated bandwidth where
needed, they greatly increased performance


Traditional switches segment only unicast,
or node
-
to
-
node, traffic


They do not limit broadcast traffic (packets
or multicast traffic

Standard Switched Network

Standard Switched Network

PCs

Server

Hub

Corporate Router

Hub

Hub

Hub

PCs

PCs

PCs

Switch

Switch

WAN

VLAN Solution


VLANs offer an effective solution to
swamped routers and broadcast storms


limiting the distribution of broadcast,
multicast and unicast traffic, they can help
free up bandwidth


Simple management from a management
console rather than the wiring closet.


Enhanced network security

VLAN Solution

Server

Corporate Router

Hub

PCs

Switch

WAN

Marketing

Engineering

Sales

Types of VLANS


Port
-
based VLAN



The administrator assigns each port of a switch to a VLAN



The switch determines the VLAN membership of each packet by
noting the port on which it arrives



Reassignment is necessary when a user moves to a different
location



Repeater connection means that all users are automatically
assigned to the same VLAN



Types of VLANS

1

2

3

4

5

6

7

8

9

Port
-
based
VLAN
Switch

Marketing

Engineering

Sales

Types of VLANS


MAC address
-
based VLAN



LAN membership of a packet is determined by ist source or
destination MAC address



Each switch maintains a table of MAC addresses and their
corresponding VLAN memberships



A single MAC address cannot easily be a member of multiple
VLANs



Types of VLANS


Layer 3 (or protocol)
-
based VLANs



The VLAN membership of a packet is based on protocols (IP, IPX,
Netbios, etc.) and Layer 3 addresses



An IP subnet or an IPX network can each be assigned their own
VLAN



Protocol
-
based membership allows the administrator to assign non
-
routable protocols, such as Netbios or DECNET




Types of VLANS



Implicit:

VLAN membership is indicated by the MAC
address. In this case,all switches that support a particular
VLAN must share a table of member MAC addresses.



Explicit:

A tag is added to the packet to indicate VLAN
membership. Cisco ISL and the IEEE 802.1q VLAN
specifications both use this method.

Distinction between VLAN implementations is the method
used to indicate membership

VLAN Standard 802.1q


IEEE 802.1q specification is going to support
port
-
based membership and explicit tagging


IEEE 802.1p, defines the use of priority bits,
which are part of the explicit VLAN tag as defined
in 802.1q


VLAN Terms


VLAN ID:
unique number (between 1 and 4094)
that identifies a particular VLAN



VLAN Name:
32
-
character alphanumeric name
associated with a VLAN ID



Filtering Database:
Database structure within the
switch that keeps track of the associations
between MAC addresses, VLANs, and interface
(port) numbers

VLAN Terms


Filtering Database ID (FID):
Addressing
information that the device learns about a VLAN is
stored in the filtering database assigned to that
VLAN



Tag Header (VLAN Tag):
Four bytes of data
inserted in a frame that identifies the VLAN/frame
classification



Port VLAN ID (PVID):
Identifies the VLAN into
which untagged frames are classified according to
a specific port

VLAN Terms


1Q Trunk:
connection between 802.1Q
switches that passes only traffic with
VLAN
Tag Header inserted in the frame.
1Q Trunk
drops all incoming frames that do not have a
VLAN tag



1D Trunk:

connection from a switch that
passes only untagged traffic

WAN Technologies


What is a wide area network?


Interconnected LANs may be in the same
geographic area or may be separated from one
another by great distances. When the LANs are
geographically disperse, they are connected into
a wide area network (WAN)


WAN Technologies


Two types of WAN:



Point
-
to
-
point WAN


ISDN



Cloud WAN


ATM


Frame Relay


Point
-
to
-
point WAN

Slough

Islandia

Darmstadt

Paris



Dedicated Connections



Fixed Speed



Administration overhead



Privately or PTT operated

Cloud WAN


Transparent Connections



Easy administration



Flexible Speed



Often PTT operated

Slough

Islandia

Darmstadt

Paris

Cloud WAN

Frame Relay


Initial proposals were submitted to the
International Telecommunication Union
Telecommunication Standardization Sector
(ITU
-
T) in 1984


Major development in Frame Relay’s
history in 1990 by Cisco Systems,
StrataCom,Northern Telecom, and Digital
Equipment Corporation

Frame Relay


Cloud WAN


Inital standard 1988 (I.122)


Speeds between 56Kbps to 2Mbps and
higher


Frame Relay Terms


Frame Relay provides a packet
-
switching
data communications capability


Two types of devices


User devices are
data terminal equipment
(
DTE)


Network equipment that interfaces to DTE is a
data circuit
-
terminating equipment (
DCE)


Communication over Permanent Virtual
Circuits (PVC)


Frame Relay Terms

Frame Relay Network

Switching Node

Permanent

Virtual Circuit

DTE

DCE

DTE

DCE

Frame Relay Terms


The DLCI (
Data Link Connection
Identifier
)
identifies the logical connection
that is multiplexed into the physical channel


DLCIs have local significance; the end
devices at two different ends of a
connection may use a different DLCI to
refer to that same connection


Frame Relay Terms

DLCI=12

DLCI=12

DLCI=64

DLCI=82

Switching Node

Permanent

Virtual Circuit

Slough

Islandia

Darmstadt

Paris

WAN

Frame Relay Terms

Frame Relay

Network

Router

Data Link Connection

(Logical)

Channel

(Physical)

Frame Relay Terms


Forward Explicit Congestion Notification

(FECN) bit is set by the Frame Relay
network in a frame to tell the DTE receiving
that frame that congestion was experienced
in the path from source to destination


Backward Explicit Congestion
Notification

(BECN) bit is set by the Frame
Relay network in frames traveling in the
opposite direction from frames
encountering a congested path.

Frame Relay Terms


Frame Relay extensions are referred to
collectively as the
local management
interface
(LMI)


connection identifiers global rather than local
significance


Virtual circuit status messages

reporting the
existence of new PVCs and the deletion of
already existing PVCs

Hybrid Frame Relay

Video/Teleconference

Router

Router

Multiplexer

Multiplexer

PBX

Frame Relay

Network


RFC 1315: MIB for Frame Relay DTEs

Frame Relay Management

ATM


Asynchronous Transfer Mode /ATM)
can transmit
voice, video, data, and graphics across LANs,
metropolitan area networks (MANs), and WANs



ATM is an international standard defined by ANSI
and ITU
-
TSS (formerly CCITT) and the
ATM
Forum (jointly founded in 1991 by Cisco
Systems,NET/ADAPTIVE, Northern Telecom,
and Sprint)

ATM


Connection oriented


dedicated links existing between network
devices


Cell
-
switching


segment data at high speeds into units called
cell
s of 52 octets length


Multiplexing technology


single network for all traffic types, including
voice, data, graphics, and video

ATM

ATM

Network

ATM Switch

ATM Switch

ATM Switch

LAN Switch

ATM Uplink


ATM stations connecting to the ATM network,
arrange a contract with the network based on
Quality of Service (
QoS
) of the User
-
to
-
Network Interface (
UNI
) specifications


ATM will be available at 155 Mbps through an
interface to Synchronous Optical Network
(SONET)


SONET will eventually allow ATM to be
deployed at rates of 622 Mbps, 1.2 Gbps, and
2.4 Gbps



ATM Terms

ATM Terms


ATM Adaptation Layer 1(
AAL/1
) supports
connection
-
orientated services for traffic
that is constant which
require timing
synchronization

and
constant bit rate
service

like video signals



ATM Adaptation Layer 3/4
(AAL/3,AAL/4) is designed for both
connectionless and connection
-
oriented
variable bit rate services

ATM Terms

ATM Terms

ATM Terms


Virtual connections are made of Virtual
Channels (VCs) and virtual paths (VPs)
which are based on the operation and nature
of these virtual connections


Virtual channel (VC) is a single connection
between two ATM devices


The channel is given a unique identifier,
called a Virtual Channel Identifier (VCI)

ATM Terms


Virtual paths are groups of VCs that are
carried between two ATM interfaces



VPs are given unique identifiers, called
Virtual Path Identifiers (VPI).


A Virtual Channel Connection (VCC) is
the end
-
to
-
end path that an ATM signal
takes from its source to its destination


A VCC is made up of a series of
intermediate hops, that are each identified
by their respective VCIs and VPIs

ATM Terms

ATM Terms

Source 1

Source 2

Destination 2

Destination 1

VCI: 33

VPI: 11

VCI: 20

VPI: 09

VCI: 73

VPI: 19

VCI: 48

VPI: 62

VCI: 15

VPI: 62

VCI: 41

VPI: 12

ATM Switch

ATM Switch

VCC 1

VCC 2


Permanent Virtual Channels (PVCs) are
manually established once and kept up until
removed


Switched Virtual Channels (SVCs)
established temporarily, used for the
duration of a transmission or series of
transmissions, and then eliminated by the
network

ATM Terms

ATM Cell

Data Field

Header

5 Bytes

48 Bytes

ATM cell stream


RFC 1695

AToM MIB

ATM Management