Tài liệu Cramsession: Cisco WAN Switching Certification doc

Addressing Node Header Type VPI/VCI Derivation Where Used BAM-BPX switch Addressing Mode STI Node derives VPI/VCI IPX switch to BPX switch, or between IPX nodes CAM-Cloud User defined

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Contents:

Contents: 1

ATM Basics 3

ATM Model 3

ATM Headers 3

ATM Addressing 5

Cisco ATM Addressing 5

ATM Adaptation Layer 5

Quality of Service 6

Service Categories 6

Frame Relay Basics 7

Voice Basics 8

Analog to Digital Conversion 9

Optimization 9

Signaling 10

General Installation 12

Tools Required 12

Installation Outline 12

Command Line Interface (CLI) 13

BPX 8600 Series 17

Card Types 17

Installing BPX Cards 17

Initial Configuration 20

IGX 8400 Series 22

Card Installation 22

MGX Series Installation 29

MGX 8220 29

MGX 8850 32

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MGX 8850 Interface Cards 35

Cisco WAN View 38

Cisco Wan Manager (CWM) 40

Components 40

Additional Features 41

Software and Firmware Upgrades 42

Downloading from CWM workstation 43

Download from a Switch 43

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ATM Basics

ATM is a packet-switched technology based on a 53-byte packet called a cell Each cell is divided into a 5-byte header and a 48-byte payload The short, fixed length cell reduces delay and jitter, allowing time sensitive information such as voice and video to be transported along with data There are various transmission media and rates available with bandwidth measured in megabits to gigabits

ATM Model

ATM is based on Broadband Integrated Services Digital Network, an extension of ISDN Similar to the OSI model, B-ISDN uses a seven-layer model ATM redefines the lower 3 layers into the Physical Layer, the ATM Layer and the ATM Adaptation Layer

• The Physical Medium sub-layer (PMD) interfaces with the physical medium

• The Transmission Control sub-layer handles cell extraction from the data stream and error checking

ATM Headers

The ATM Cell has a 5-byte header, with the remaining 48-bytes left for payload (data)

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There are two standard headers Cisco added an addition header type to allow for advanced ATM features

• User-to-Network Interface (UNI) header-specifies interface between a user

device and a network Note: A user device is not just a computer interface

It can be a router or switch as well

• Network-to-Network Interface (NNI) header-specifies interface between two networks Usually a private ATM network and a public ATM network

• STI header-used between to Cisco ATM switching nodes to allow advanced network features

• Flow Control (4-bits)-a UNI field for controlling access and flow control Usually all zeros, as there is no defined standards

• Virtual Path Indicator (VPI)-identifies the path to be taken by the ATM cell

• Virtual Circuit Indicator (VCI)-indicates the circuit number on the path

• Payload Type Indicator (PTI, 3-bits)-the type of data being carried in the payload High order bit is 0 for user data and 1 for connection management information, second bit indicates if there was congestion, and the third bit show if user data is from customer premises equipment

• Payload Class (4-bits)-STI field indicating classes of service and BPX switch queues

• Cell Loss Priority bit (CL)-indicates the cell may be discarded if congestion is encountered

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ATM Addressing

• VCI identifies the circuit or connection

• VPI identifies the virtual path

• The path can be seen as a trunk that carries multiple circuits between

switches

• VCI is 16-bits allowing 65, 535 circuit numbers For the STI header VCI is

8-bits for 256 circuits

• VPI is 8-bits for the UNI header, 12-bits for the NNI header (4096 paths), and

10-bits for the STI header (1024 paths)

Cisco ATM Addressing

Three modes available depending on the hardware being used

Addressing Node Header Type VPI/VCI Derivation Where Used

BAM-BPX switch

Addressing Mode STI Node derives VPI/VCI IPX switch to BPX switch, or between IPX nodes

CAM-Cloud

User defined VPI Node derived VCI

Between IPX or IGX nodes and on networks switched on VPI only

SAM-Simple

Between IPX or IGX nodes and on networks where routing is user programmed

ATM Adaptation Layer

• ATM Adaptation Level (AAL)-used to convert data from various sources and

convert it to 48-byte segments that fit the payload of ATM cells

• Four classifications of source traffic are outlined

Adaptation Layer

i C t t bit Compressed Voice d Vid Frame-relay, SNA, TCP/IP il

SMDS

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voice, Constant

• Consists of Convergence sub-layer (CS) and Segmentation and Reassembly sub-layer (SAR)

• CS receives data from the applications and sends it to the SAR to be

segmented into 48-byte blocks

Quality of Service

These are some of the most important QoS parameters:

• Peak Cell Rate (PCR)-maximum rate a sender can send cells

• Sustained Cell Rate (SCR)-required cell rate averaged over a long interval

• Minimum Cell Rate (MCR)-minimum acceptable rate of cells per second

• Cell Loss Ratio (CLR)-the fraction of cells not delivered or delivered late

• Cell Transfer Delay (CTD)-time from source to destination (transmit time)

• Cell Error Ratio (CER)-fraction of cells delivered with incorrect bits

• Cell Delay Variation (CDV or Jitter)-how regularly cells are delivered Cells from one conversation on a multiplexed connection may be delayed while cells from another conversation are delivered

• Cell Delay Variation Tolerance (CDVT)-amount of variation in cell

transmission times Specified separately for PCR and SCR

Service Categories

The ATM Forum specifies four service categories:

• Constant Bit Rate (CBR)-entire connection, from source to destination,

including intermediary switches, provides a set amount of bandwidth at all times Expensive because bandwidth is reserved even if it is not used

• Variable Bit Rate (VBR)- guarantees an average bit rate over time, but allows

a higher peak bit rate, with no cells lost, for a certain amount of time each minute VBR is broken into two subclasses real time (rt) and non-real time (nrt)

voice or video connections using compression or noise reduction

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QoS is still needed

• Available Bit Rate (ABR)-bit rate varies according to network conditions up to

a stated maximum Source adjusts transmission rate due to network

information received from the network

• Unspecified Bit Rate (UBR)-no set bit rate guarantee Allows a transmission rate up to a certain maximum, with no guarantee of cell loss or delivery

Frame Relay Basics

Frame relay:

• Defines a connection between user equipment and a WAN, not the interface

or protocols of the WAN itself Usually describes a LAN-to-LAN connection

• A standard optimized for the transport of protocol-oriented data

• Defines network paths using statistical multiplexing (creates virtual circuits)

• Does not allocate bandwidth until data needs to be transmitted

• Combines packet switching and port sharing with time division multiplexing circuit switching to allow multiple point-to-point permanent virtual circuits over a single physical interface

• Operates only on the Data Link and Physical layers of the OSI model Routing

is general handled by the Network layer protocol

Components of Frame Relay

• Committed Information Rate (CIR)-rate of data transfer under normal

operations Generally the contracted rate from the public service provider CIR should never be set higher than the speed of the slowest physical

connection on a VC CIR of 0=best effort

• User-Network Interface (UNI)-describes a connection between user

equipment and a frame relay network Usually, a router (DTE) and the

service provider

• Network-Network Interface-describes connection between frame relay

networks

• Local Management Interface (LMI)-monitors the status of DLCIs by

periodically polling the network Can be used to exchange status information between frame devices and the network Also supports multicasting, global addressing and flow control Cisco switches support LMI

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• Data Link Connection Identifier (DLCI)-10-bit routing address of the PVC at a particular UNI or NNI Some DLCIs are reserve for signaling, management and future use so only 16 to 1007 are used to address virtual circuits

• Command/Response (C/R)-not used Always set to 0

• Extended Address (EA)-allows the header to be lengthened to 3 or 4 bytes allowing a DLCI longer than 10-bits (more VC addresses)

• Forward Explicit Congestion Notification (FECN)-set to 1 by the frame network when congestion is occurring on the packet forwarding direction of the frame

• Backward Explicit Congestion Notification (BECN)- set to 1 by the frame network when congestion is occurring on the reversed packet forwarding direction of the frame

• Discard Eligibility (DE)-set by the end node to indicate frames to be discard if congestion occurs

• Data-also called the information field May be as large as 4,520 bytes, but is more efficient with a size of less than 4k

• Frame Check Sequence (FCS)-standard cyclic redundancy check that detects bit errors in the frame

Voice Basics

Human voice can achieve a frequency of up to 4000 Hz (usually between 300 to

3000 Hz)

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Analog to Digital Conversion

• The coder-decoder (CODEC) converts analog voice signals to digital signals using pulse code modulation (PCM)

• Multiple digital voice signals can be combined into a single channel using a multiplexer (MUX) The process is called Time Division Multiplexing (TDM)

• A T1 connection can contain 24 channels or timeslots (called DS0s) of 64 kbps each

• An E1 or J1 connection has 30 channels with two additional timeslots for framing and signaling

Sampling

• General rule is that sample rate should be twice the frequency of the signal to

be sampled (example: the human voice is capable of 4000 Hz so a sample rate of 8000 samples per second would be required)

• Each sample is converted into a 8 bit word (8 bits per sample x 8000 samples per sec = 64kbps)

Companding

• Part of the PCM process that determines the digital bits used to represent the voice signals (whether the value of a sample is a digital one or zero)

• 2 companding laws:

o A-law: linear at lower levels and logarithmic at higher levels Used in Europe, Asia, Australia and South America

• Different companding methods are not compatible (international voice traffic requires conversion from one companding method to another)

• Defined in ITU-T G.726 recommendation

• The following rates are available:

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• Does not use A-law or M-law coding

• Not reliable for data or fax traffic above 4800 kbps

Code Excited Linear Prediction (CELP) Compression

• Better than ADPCM at the same or higher data rate

• Uses know characteristics of human speech to provide compression

• Based on ITU-T G.729 standard

• 8, 16, 24 and 32 kbps data rates are possible

Signaling occurs between a subscriber and a switch or a switch and a switch

Signaling is the process of sending status and control information between network elements In voice communications, signaling is generally used to initiate a call or connection

Subscriber to switch signaling is used from handset to PBX and includes on-hook, off-hook detection and dialing

Switch to switch (or interswitch) signaling is used between the local exchange carrier (LEC) and interexchange carrier (IXC) or between PBX and PBX (or switch)

Interswitch signaling is generally digital

Two types of interswitch signaling:

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• Channel Associated Signaling (CAS)-signaling is sent on the same path as the voice traffic with the signaling bits in a specified location on each

channel Signal states are limited by number of bits used for signaling

• Common Channel Signaling (CCS)-independent signal channels carry the signal information for the voice channels Generally more complex than CAS and allows for more diverse signal states

CAS vs CCS signaling

T1 interface Robbed bit signaling Least

significant bit of every sixth frame is robbed

Timeslot 24

E1 interface Timeslot 16 carries four

signaling bits per channel Timeslot 16 as a clear channel J1 interface Timeslot 0 carries one signaling

bit per channel Timeslot 16 as a clear channel

Versatility Limited number of signaling

Dialing Formats

There are two different dialing formats used by most switches:

• Pulse-each number dialed generates a number of pulses (dialing a three would generate 3 pulses)

• Dual-tone Multifrequency (DTMF or tone)-each number dialed generates two tones that uniquely identify the number

Echo

Echo is caused by a difference in impedance between two network entities (usually involving conversion from two-wire to four-wire transmission) This difference in impedance causes reflections of the signal perceived as echo Echo is always present

in a voice network Echo is not a problem unless it reaches an unacceptable level (delays of less than 250ms are generally considered acceptable)

Causes of delay:

• Compression-all compression algorithms have an inherent delay

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An echo canceller can be added to reduce echo An echo canceller compares

transmit and receive signals to measure loss and delay of the reflected signal and subtracts the expected echo power level from the receive signal

General Installation

Tools Required

• Box Knife

• Standard blade screwdriver set

• Phillips screwdriver set

• Wrench set, including adjustable wrench and/or channel locks

• Allen key set

• Grounding wrist strap

Installation Outline

Preliminary Steps

1 Prepare the site for equipment installation

• Location should have restricted access

• Sufficient area should be available to access the equipment

• The proper power requirements need to be met

• Confirm that UPS meets Cisco requirements

• Airflow and cooling must be suitable for the equipment being installed

2 Verify that all parts ordered are present and in good condition Record all part numbers and serial numbers

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6 Install the cable management system and connect the cables to the required ports

7 Connect a management terminal or Cisco WAN Manager workstation to the console port

Installation troubleshooting

If there is no power to the switch:

• Check the power cables

• Check Circuit breaker

• Card short circuit (pull and reseat all cards)

• Power supply fault

No LED lit on a single card:

• Remove and reseat card

• Check card fuse if applicable

• Replace card If replacement does not fix problem, backplane

Alarm Indicator on Card:

• Get card status with dspcds

• Reset card with resetcd f

• Remove and reseat card

Command Line Interface (CLI)

Connect to an IGX or BPX with a PC using a terminal emulator (hyperterm), or a terminal connected via the control port, a LAN connection, or remotely using a

modem connected to the auxiliary port

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• Once connected, hit enter to bring up the command screen

• Enter user name at the logon prompt

• Enter password at the password prompt

• The bye command ends the session

Use vt <nodename> to create a virtual terminal session on a remote node

• The bye command returns user to local session

Command Screen Format

• Top line displays node name, current user, software revision, date, time and time zone

• The middle of the screen shows information returned by executed commands

• The bottom of the screen displays prompt for current command or next command

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• bye –ends local or remote session

• vt –used to start virtual terminal session with remote nodes

redundant pair) back card connected to IGX

number of the connection DLCI only has local significance to the port

number of the connection DLCI is unique to port for entire network

Viewing Node Configuration

Display commands are also useful for troubleshooting

• Display cards in shelf-dspcds

• Display status, serial number and revision of a card-dspcd

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• Display redundant cards (y-pairs)-dspcdred

• Display LAN port configuration-dsplancnf

• Display power supply status and cabinet temperature-dsppwr

• Display control port and auxiliary port configuration-dsptermcnf

• Display function of control port and auxiliary port-dsptermfunc

privilege level than you are logged in as)

• Remove users with deluser

Management Workstation

On the Switch:

• Set up the LAN port with cnflan

• Configure the SNMP get and set (read and write) community names with

• Configure the IP for the statistics manager, if you are using Cisco WAN Manager Statistics Collection Manager, using cnfstatmast (cnfstatmgr on the MGX switches)

Alarms

• Use dspnw to show list of network nodes and trunk alarm status

• Use dspnds to list name, type and alarm status of nodes on the network

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Redundancy

• Set up card redundancy-addyred (or addcdred)

• Switch between active and redundant cards-resetcd

• Switch between active and standby processor-switchcc

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• When installing cards, follow ESD precautions

• Slot 7 is reserved for BCC card Redundant nodes have a BCC card in slots 7 and 8

• Slot 15 is for the ASM/LM-ASM card pair

• Slots 1-6 and 10-15 for all interface cards

19.2 Gbps Operation

The BPX switches support a 9.6 or a 19.2 Gbps backplane For 19.2 Gbps support, you need:

• 19.2 Gbps backplane identified by white slot fuses on bottom rear of

backplane (or result of “Word #2=0001” from dspbpnv command)

• Backplane NOVRAM that indicates the backplane is 19.2 Gbps capable

• BCC-4 or later controller

• Switch software release 8.1.18 or later

• At least one BXM card

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Table of BPX Cards

BPX-BCC-32 Broadband controller card, can be installed in redundant pairs

Uses System Software ver 7.X (7.2.84 and above) or 8.X (8.1.12 and above)

Front

Uses System Software 8.4 or above, has 64+ MB or RAM and supports 19.2 Gbps BXM card operation Can support VSI or MPLS

Front

BPX-BCC-3-BC Back card used with BCC-3 or BCC-4 (also called LM-BCC) Back

Network Interface Group

4 or 8 port OC-3/STM-1 card Used in either network interface or

Back

BPX-BXM-622

BPX-BXM-622-2

1 or 2 OC-12/STM 4 ports Used in either network interface or

BPX-BME Used with SMF-622-2 back card for multicast connections Port 1

loops to port 2, tx to rx and rx to tx (cross-over) Back BPX-SMF-622-BC

BPX-SMFLR-622-BC

Back cards for BXM-622 Single mode fiber, single mode, long range fiber and extra long-range fiber respectively XLR supports 1500mm interface

Back

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BPX-MMF-2-BC

BPX-SMF-2-BC

BPX-SMFLR-2-BC

OC-3/STM-1 interface card for BNI-155 or ASI-155 front card

Multi-mode fiber, single mode fiber and single mode, long range fiber respectively

Back

Service Interface Group

BPX-T3-BC Line module with 2 physical T3 ports for use with ASI-1-2T3 Back

BPX-E3-BC Line module with 2 physical E3 ports for use with ASI-1-2E3 Back

BPX-MMF-2-BC

BPX-SMF-2-BC

BPX-SMFLR-2-BC

OC-3/STM-1 interface card for BNI-155 or ASI-155 front card

Multi-mode fiber, single mode fiber and single mode, long range fiber respectively

Back

Power Supply Group

48 Volt DC Power Supply Optional AC Power Supply

Initial Configuration

1 Set up the node

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2 Set up the trunks (use dspcds to ensure proper cards are installed)

o Up trunk at each node-uptrk

o Configure trunk parameters-cnftrk

o Add trunks at each node-addtrk

o Configure redundancy (if require)- addyred

3 Configure IGX interface shelf (if present)

o Add IGX as shelf at BPX-addshelf

4 Add MGX 8220 Shelf (if present)

o Add MGX as a shelf at BPX-addshelf

5 Set up ATM services

o Activate line-upln

o Configure line-cnfln

o Activate ports-upport

o Configure port-cnfport

6 Configure ATM connections

7 Set up ATM to Frame Relay (ATF)

o Specify connection class-cnfcls

8 Configure Interface Shelf to Frame Relay Connections

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IGX 8400 Series

• Multi-service switch supports WAN voice, data and video

• 1 Gbps cellbus with a 2 Gbps backup bus

• Six models available:

Card Installation

IGX 8410 (8 Slot configurations)

IGX 8420 (16 Slot configurations)

Tiêu đề	Cisco WAN Switching Certification
Trường học	BrainBuzz Academy
Chuyên ngành	Networking / Cisco WAN Switching
Thể loại	Study Guide
Năm xuất bản	2001

Định dạng
Số trang	44
Dung lượng	438,55 KB