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Introduction to
Networking Technologies
Stefan Karsten
Technical Consultant
e-mail: [email protected]
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
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
Traditional Fully Routed Network
• 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
Router
Hub
PCs
Hub
PCs
Server
Hub
PCs
Server
Server
Standard Switched Network
• 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
Corporate Router
Server
WAN
Switch
Hub
Switch
Hub
PCs
Hub
PCs
Hub
PCs
PCs
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
Hub
Marketing
Sales
Engineering
PCs
Corporate Router
Switch
WAN
Server
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
Marketing
Port-based
VLAN
Switch
1
2
3
Engineering
4
5
6
Sales
7
8
9
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 nonroutable protocols, such as Netbios or DECNET
Types of VLANS
Distinction between VLAN implementations is the method
used to indicate membership
• 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.
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
• Dedicated Connections
• Fixed Speed
• Administration overhead
• Privately or PTT operated
Paris
Darmstadt
Cloud WAN
Slough
Islandia
•Transparent Connections
• Easy administration
• Flexible Speed
• Often PTT operated
Cloud WAN
Paris
Darmstadt
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
DTE
DTE
Frame Relay Network
DCE
DCE
Switching Node
Permanent
Virtual Circuit
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
Slough
Islandia
DLCI=12
DLCI=12
Paris
DLCI=82
WAN
DLCI=64
Darmstadt
Switching Node
Permanent
Virtual Circuit
Frame Relay Terms
Frame Relay
Network
Data Link Connection
(Logical)
Channel
(Physical)
Router
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
Router
Multiplexer
Frame Relay
Network
PBX
Multiplexer
Router
Video/Teleconference
Frame Relay Management
• RFC 1315: MIB for Frame Relay DTEs
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
cells of 52 octets length
• Multiplexing technology
– single network for all traffic types, including
voice, data, graphics, and video
ATM
ATM Switch
ATM
Network
ATM Switch
ATM Switch
ATM Uplink
LAN Switch
ATM Terms
• ATM stations connecting to the ATM network,
arrange a contract with the network based on
Quality of Service (QoS) of the User-toNetwork 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 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).
ATM Terms
• 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
Source 1
Destination 1
VCC 1
VCI: 41
VPI: 12
VCI: 73
VPI: 19
VCI: 15
VPI: 62
ATM Switch
VCI: 33
VPI: 11
Source 2
ATM Switch
VCI: 48
VPI: 62
VCC 2
VCI: 20
VPI: 09
Destination 2
ATM Terms
• 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 Cell
Header
5 Bytes
Data Field
48 Bytes
ATM cell stream
ATM Management
• RFC 1695 –AToM MIB