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: 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 Mbps (OC-1) to 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 STS-N 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: 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 “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 (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 (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 (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 (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 (p. 615)

SONET Concentrators SONET concentrators operate the same way as electrical concentrators and hubs, concentrating OC-3, OC-12, and OC- 48 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 (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: Network monitoring and testing Network provisioning Maintenance Network restoration Refer to Figure (p. 618)

SONET Digital Cross-Connects (SDXCs) (Continue..) SDXCs come into two types: 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 (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: 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: 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 The Three Configuration Options Command Line Interface (CLI) Visual Switch Manager (VSM) Original Menu System 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

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

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