Transcript WAN_Unit_10-SONET

Terms Defined
SONET is a method (not a network) of providing a high-speed,
low error-rate, international, fiber-optic multiplexed transmission
standard for interface between the PTTs, IXCs, and LECs.
It also provides a technology that allows the major IXCs and
PTTs to internationally standardize and control broadband
network transport media through a common fiber interface
called a midspan meet.
Vendors and service providers consider SONET a common
interconnectivity medium for direct fiber services such as SMDS
and ATM
SONET uses both synchronous and asynchronous transfer
modes through the use of a fixed data-transfer frame format
including user data, management, maintenance, and overhead.
STANDARDS
SONET standards have been introduced in three phases:
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Phase I : Hardware specifications
Phase II: multiple vendor connectivity and management
Phase III: builds upon Phase II providing additional network
management, performance monitoring, and control functions.
SONET STRUCTURE
The SONET Optical Carrier (OC-N) structure consists of OC-N
levels multiplexed to form higher-speed transport circuits that
range into the gigabits range and provide an alternative to
aggregating multiple DS1 and DS3 transmission facilities
The basic structure of SONET is built around Synchronous
Transport Signal level 1 (STS-1) transport through an Optical
Carrier (OC-N) signal over fiber optics.
An aggregate 51,84 Mbps STS-1 bit stream, when converted
from “electrical” to “fiber optic” is called Optical Carrier-1 (OC-1)
It is composed of a transmission of 810-byte frames sent at a
rate of 8000 times per second.
SONET STRUCTURE (Continue…)
Current SONET speeds range from 51.84 Mbps (OC-1) to
9.95328 Gbps (OC-192)
Any subrate signals below OC-1 are multiplexed to form a
single OC-1 channel.
Refer to Table 15.1 (p. 597)
Refer to Table 15.2 (p. 597)
Multiplexing
SONET provides direct multiplexing of both SONET speeds and
current asynchronous and synchronous services into the STSN payload.
Payload types range from DS1 and DS3 to OC-3c and OC-12c
ATM and SDH/PDH payloads.
Refer to Figure 15.1 (p.598)
Other major advantage of SONET is that each individual signal
down to the DS1 level can be accessed without the need to
demultiplex and remultiplex the entire OC-N level signal.
This is commonly accomplished through a SONET Digital
Cross-Connect (DXC)
Multiplexing (Continue…)
It is important to note that SONET multiplexing requires an
extremely stable clocking source with a stable reference point.
Thus, the frequency of every clock within the network must be
the same or synchronous with one another.
This central clocking source must be at least a Stratum level 3
source, with a Stratum 1 preferred for greatest accuracy.
SONET Architecture Layers
There are four layers to the SONET architecture:
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physical: defines the physcial fiber type, path, and characteristics
section: builds the SONET frames from either lower SONET interfaces or
electrical interfaces
line: provides synchronization, channel multiplexing, and protection
switching.
path: manages the actual data transport across the SONET network, as
well as the pointer function
Refer to Figure 15.2 (p. 599)
Refer to Figure 15.3 (p. 600)
OC-N Midspan Fiber Meet
The OC-N midspan fiber meet allows CPE, LEC, and IXC
hardware from different vendors to interface with each other via
SONET.
It provides a single platform base for access from the central
office to the CPE
Refer to Figure 15.5 (p. 601)
Data communications Channels (DCC)
SONET transmissions also contain communications channels
which transmit network management information between
network elements.
This information includes alarm, control, maintenance, and
general monitoring status.
Each SONET terminal and regenerator uses a 192 kbps
channel, and each optical line between terminal multiplexers
uses a 576 kbps channel for the DDC
Frame Format and OAM Elements
SONET frame payloads are not synchronized by a common
clock even though SONET is a synchronous technology.
The standard SONET frame has two major pieces - payload
and overhead - functional in Phase I implementations.
Refer to Figure 15.6
Payload
The payload is defined as the actual data to be transported
across the SONET path.
Payloads can vary depending on the OC speed of transport.
Payload (continue…)
Payloads can take many forms, such as typical T-carrier
channels (e.g., DS3), FDDI, SMDS, ATM, or Virtual Tributaries
(VTs) of various sizes.
Payloads are backward compatible with the North American,
European, and Pacific Rim standard transport technologies (DS
and CEPT)
The payload envelope of the frame can vary in size in 774-byte
increments, and the term used for the envelope is Synchronous
Payload Envelope (SPE)
SONET uses “pointers” to provide synchronization to avoid
having timing and slipping problems
Virtual Tributary
Virtual tributaries are the building blocks of the CPE.
The label VTxx designates virtual tributaries of xx Mbps.
These virtual tributaries are labeled as VT1.5 for DS1, VT3 for
DS1C (3 Mbps), VT2 for CEPT E1, and VT6 for DS2 (6 Mbps).
Refer to Table 15.3 (p. 607)
VTs are combined to form VT groups. These VT groups consist
exclusively of three VT1.5s, four VT2s, two VT3s, or one VT6
within a 9-row by 12-column portion of the SPE
Virtual Tributary (continue…)
VTs can either operate in
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“locked mode” - fixes the VT structure within an STS-1 and is designated
for channelized operation
“floating mode” - allows these values to be changed by cross-connects
and switches and is designated for unchannelized operation.
The common tributary is VT1.5, which supports a virtual
tributary of 1.5 Mbps through a DS1 transport envelope.
VTs run from the VT1.5 through a VT6 (DS2)
Refer to Table 15.4 (p. 608)
Synchronization and Pointers
pointers are used by SONET devices to easily identify
subchannels down to the DS0 level within a SONET
transmission.
These pointers are located within the line overhead portion of
each frame.
Refer to Figure 15.12 (p. 609)
pointers are lso used to identify virtual tributaires (VTs) within
an SPE
Overhead and the Control Field
The SONET overhead structure parallels the existing telephone network,
with three layers to match section, line, and path segments.
Refer to Figure 15.13 (p. 609)
Bit Interleave Parity Check (BIP-8)
Parity is provided through a 1-byte Bit Interleave Parity (BIP-8) code at each
section, line and path segment of the frame.
The section BIP assures error-free transport between regenerators,
The line BIP assures error-free transport between terminating devices
The path BIP assures error-free transport between line termination
equipment.
Bit Stuffing
When the incoming tributary data rates cannot fully meet the
STS-N rate, the SONET device performs bit stuffing to achieve
the desired badnwidth.
This is as simple as inserting extra bits into the data stream,
which are then stripped off at the destination SONET device.
Bit stuffing is also used for frame synchronization. This
technique is used when the access hardware and network
hardware are using different timing sources having clock
frequency differences.
OAM Structure
The Operations, Administration, and Maintenance (OAM)
functions of SONET are divided into three levels
F1: defines OAM flows between regenerator sections and
between regenerators and LTE
F2: defines OAM flows between LTEs at the termination of
section end points.
F3: defines OAM flows between PTE elements that perform
payload assembly and disassembly, error check operations,
and cell delineation over the transmission path.
SONET Hardware
The most common equipment term used is the SONET
terminal.
The word terminal, or terminal adapter, is used at times to
represent a SONET multiplexer, DXC, and even a switch.
OC-N -to-OC-N SONET devices, those that provide the
interface of OC-12 and OC-48 speeds to higher-speed
tributaries like OC-192, are most often called terminals as well.
The primary benefit of SONET Central Office (CO) terminal
equipment - terminals, multiplexers, terminal multiplexers,
DXCs, and switches - is the reduction of equipment required for
DS1, DS3, and OC-N connectivity and interswitch trunking.
SONET Terminating Multiplexers
Terminating multiplexers provide user access to the SONET
network
Terminating multiplexers, also called PTE, turn electrical
interfaces into optical signals by multiplexing multiple DS1,
DS1C, DS2, DS3, or E1 VTs into the STS-N signals required for
OC-N transport.
These devices are configured in point-to-point configurations.
The most common is the point-to-point, four-fiber configuration
over the “line”, where two fibers are connected between two
terminals
Refer to Figure 15.16 (p. 614)
SONET Terminating Multiplexers
SONET terminals are typically connected in fiber rings, with
each device connected to another through a two-pair fiber
configuration.
Refer to Figure 15.17 (p. 614)
For SONET transmission LTE terminal adapters are also used
which interface up to 84 DS1s into a single OC-3 interface
Refer to Figure 15.18 (p. 615)
SONET Concentrators
SONET concentrators operate the same way as electrical
concentrators and hubs, concentrating OC-3, OC-12, and OC48 interfaces into higher-transmission rates like OC-192.
SONET Add/Drop Multiplexer (SADM)
SONET add/drop multiplexers allow the provider to drop and
add not only the lower SONET rates, but also electrical
interface rates down to the DS1 level.
Drop-and-insert, drop-and-continue, and broadcast mode are
standard features.
Refer to Figure 15.19 (p. 616)
SONET Digital Loop Carrier Systems (DLCs)
Digital Loop Carrier systems (DLCs) are used to concentrate
multiple DS0 traffic from remote terminals into a single OC-3
signal.
These devices are typically situated at the LEC and handle both
voice and data traffic, providing an interface for non-SONET
CPE, LEC, and CO switches to the SONET public network.\
DLCs have many capabilities and can handle access for many
of the data services such as N-ISDN and B-ISDN
SONET Digital Cross-Connects (SDXCs)
SDXCs allow switching and circuit grooming across all levels fo
the transmission down to the DS1 level, including those that
interface to the SDXC without being on the incoming or
outgoing transmission.
SDXCs provide SONET OC-N level cross-connect provisioning
capabilities and can also act as a SONET hub to provide both
asynchronous and synchronous user or network access.
SONET Digital Cross-Connects (SDXCs)
(Continue..)
SONET DXCs use pointers rather than traditional DXC slip
buffers to mark the beginning of a DS1 frame and allow
insertion/extraction with minimal delay.
The additional SDXC features include:
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Network monitoring and testing
Network provisioning
Maintenance
Network restoration
Refer to Figure 15.20 (p. 618)
SONET Digital Cross-Connects (SDXCs)
(Continue..)
SDXCs come into two types:
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Wideband (WDXC): lower-speed device which provides cross-connect
capability for floating VTs within an STS-N
Broadband (BDXC): higher-speed device which can both cross-connect
at DS3 (asynchronous or synchronous) and STS-1 signals and provide
concatenation of multiple STS-1 signals to STS-N levels
SONET Broadband Switches
SONET broadband switches provide the switching capability
found in major voice switches, but operate at the higher OC-N
levels.
Many SONET terminal and switch vendors are now including
SDXC capabilities within their switches.
A need also exists for this functionality in the CPE environment
interfacing many LAN and MAN technologies.
Refer to Figure 15.23 (p. 620)
SONET Regenerators and Optical Amplifiers
Regenerators reshape and boost signals that have incurred
dispersion or attenuation over long transmission distances.
SONET Equipment Vendors
SONET hardware terminal vendors can be separated into three
categories:
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category 1: vendors pushing the SONET DXC
category 2: vendors offer drop-and-insert multiplexer products.
Category 3: vendors advocate integrated SONET message switches.
Most systems today are being installed at OC-48 speeds, with
some deployment of OC-192 systems, and are all new
hardware devices.
Interfaces
The Network-Node Interface (NNI) specifies the link between
existing in-place digital transmission facilities and the SONET
network node, as well as the process for converting the
electrical signal into optical pulses for network transmission.
This is the primary interface from the electronic world into the
optical world.
There are three major SONET interface options:
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Direct CPE or CO hardware interface
Gateway device to convert to OC levels
Conversion within the SONET switch itself
Services Support
Typical services to ride over SONET networks include:
 Digital Data Service (DDS)
 N-ISDN
 ATM
 X.25/X.75
 Frame Relay
 FDDI/FDDI-II
 802.6/SMDS
With SONET, users will be able to dial up whatever bandwidth
increments are needed.
Cisco
Configuring the Catalyst 1900
Switch
Objectives
Configure the Catalyst 1900 Switch CLI
Configure the Catalyst 1900 Switch
Hostname and Passwords
Configure the Catalyst 1900 Switch
Security
Configure Virtual LANs
Configure ISL Routing
Features of the 1900 Switch
Types of Operating Systems
IOS-based
 Set-based
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The Three Configuration Options
Command Line Interface (CLI)
 Visual Switch Manager (VSM)
 Original Menu System
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Menu-based options
Catalyst 1900 Switch
Cisco 1900 IOS Configuration
Commands
Set the passwords
Set the hostname
Configure the IP address and subnet mask
Identify the interfaces
Set a description on the interfaces
Define the duplex of a port
Verify the configuration
IOS Commands (cont.)
Setting the Passwords
Setting the User Mode and Enable Mode
Passwords
 Setting the Enable Secret Password

IOS Commands (cont.)
Setting the Hostname
Setting IP Information
Configuring Switch Interfaces
10BaseT Interfaces
 FastEthernet Interfaces
 Setting Descriptions
 Viewing Descriptions
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IOS Commands (cont.)
Configuring the Port Duplex

Options
Verifying IP Connectivity
Erasing the Switch Configuration
Managing the MAC Address Table
Setting Permanent MAC Address Entries
 Setting Static MAC Address Entries
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IOS Commands (cont.)
Configuring Port Security
Using the Show Version command
Changing the LAN Switch Type
Configuring VLANs
Example
>en
#config t
Enter configuration commands, one per line. End with
CNTL/Z
(config)#hostname 1900EN
1900EN(config)#vlan 2 name sales
1900En(config)#vlan 3 name marketing
1900En(config)#vlan 4 name mis
1900EN(config)#exit
Configuring VLANs
Assigning Switch Ports to VLANs
Configuring Trunk Ports
Clearing VLANs from Trunk Ports
Verifying Trunk Ports
Configuring ISL Routing
Configuring VTP
Configuring the Domain
Adding to a VTP Domain
VTP Pruning
Restoring or Upgrading the
Catalyst 1900 IOS
Command:
copy tftp://tftp_host_address/IOS_filename
opcode
Backing Up and Restoring the Catalyst
1900 Configuration
CDP with the 1900 Switch
Commands:
sh cdp
cdp timer
cdp holdtime
Summary
Configured the Catalyst 1900 Switch
CLI
Configured the Catalyst 1900 Switch
Hostname and Passwords
Configured the Catalyst 1900 Switch
Security
Configured Virtual LANs
Configured ISL Routing