Training

Ethernet and IP Basics

Overview

– OSI Layer Model – Ethernet– IP– ARP– IP Routing– Higher Layer Protocols– VRRP– ATM Vision Network Setup– Practice

Section

OSI Layer Model

OSI Layer Model

Application

Application

Presentation

Session

Transport

Network

Data Link

Physical

Data Transport

Physical interface (cable, transceiver etc.)

Transmission, framing and error control

Data transport

Reliability and multiplexing of data transport

Adding control mechanism to data transport

Structuring of data units

Managing of communications

OSI: Open Systems Interconnection

LAN Layer and the OSI Reference Model

Data LinkLayer

MACSublayer

PhysicalLayer

Eth

ern

et

IEE

E 8

02.3

100B

aseT

To

ken

Rin

g/IE

EE

802

.5

FD

DI

LLCSublayer

IEEE 802.2

OSI Layers LAN Specifiaction

Section

Ethernet

OSI Layer Model

Ethernet Frame

PreambleSource

AddressFCS

DestinationAddress

Type Data

8 6 6 2 46-1500 4

Field Length,In Bytes

FCS = Frame Check Sequence

MAC Address: IP Data: 00 : a3 : 25

Vendorspecific

VendorID

00 : 50 : 66 IP Header

Section

IP (Internet Protocol)

OSI Layer Model

Ethernet

IP Packet

Version IHL Type of Service Total Length

Identification Flags Fragment offset

Time to Live Protocol Header Checksum

Source Address

Destination Address

Options

Data (1 Bytes – 64 kBytes)

Padding

IHL: Internet Header Length

32 Bit

IP Header

IP Data

IP Addressing

IP address comprises 32 Bits, grouped into four octets

32 Bit

8Bit 8Bit 8Bit 8Bit

C0 A8

192 168 151 44

97 2CHex:

Dec.: . . .

. . .

11000000 10101000 10010111 00101100Bin.: . ..

Network Example

192.168.151.44192.168.151.45

192.168.151.215

Section

ARP (Address Resolution Protocol)

OSI Layer Model

Ethernet

IP

ARP

• ARP: Address resolution protocol

• Communication between two Ethernet interfaces on a local network based on MAC addresses

• The address resolution protocol (ARP) provides mapping of an IP address to the unique MAC address

ARP

ARP

ARP

ARP ARP ARP ARP ARP

ARP

ARP

ARP

ARP ARP ARP ARP

ARP

ARPMAC

address

MACaddress

MACaddress

MACaddress

MACaddress

MACaddress

MACaddress

MACaddress

MACaddress

MACaddress

IP: 192.168.151.45MAC: 00:25:12:34:F2:A3

IP: 192.168.151.16MAC: 00:25:12:11:BB:C1

IP: 192.168.151.163MAC: 01:A1:23:8A:45:01

MACaddress

MACaddress

Section

IP Routing

OSI Layer Model

Ethernet

IP

ARP

Subnetting With Netmask

IP address „ANDED“ with netmask splits net into network and subnet portion

192 168 151 44IP Address: . . .255 255 255 0 Logical AND with Netmask: . . .

Network Network Network Subnet

192 168 151 0. . .Results in Subnet number:

11000000 10101000 10010111 00101100. ..11111111 11111111 11111111 00000000. ..„AND“

11000000 10101000 10010111. .. 00000000

Network Example

192.168.172.44255.255.128.0

192.168.196.63255.255.128.0

192.168.151.1255.255.128.0

192.168.13.1255.255.255.0

Router

192.168.13.234255.255.255.0

192.168.13.19255.255.255.0

Special IP Addresses

Network: 192.168.151.xNetmask: 255.255.255.0

Subnet number: 192.168.151.0Subnet broadcast: 192.168.151.255

Example:

Local host: 127.0.0.1Multicast groups: 224.0.0.0 ... 239.255.255.255

Experimental: 240.0.0.0 ... 254.255.255.255

IP Routing

Static routing

- Static entries in routing table

- Setting up Network Interface creates routing entry for local Network

- Entries made by administrator

- No dynamic changing of entries

Dynamic routing- Internet devices investigate their neighbourhood and store the information in the routing table

- These information will be collected by special protocols (OSPF, RIP, BGP)

Routing maintained by routing tableRouting table entries consist of:

- Destination IP address- Mask- Gateway- Metric (optional)- Interface (optional)

Routing decisions made on “best fit”

Section

Higher Layer Protocols

OSI Layer Model

Ethernet

IP

ARP

IP Routing

TCP / UDP

• Connection oriented• Connection status available• Order guaranteed• Assured data transport by the use of:

- Flow control- Data verification (checksum)- Data re-transmission in case of lost packets

The Transmission Control Protocol (TCP) and the User DatagramProtocol (UDP) work on top of IP.

UDP:

• Connectionless• Order guaranteed• Duplications removed• Unassured data transport (no acknowledge, no re-transmission)

TCP:

Firewall

Devides privat and public Network or two Networks

Protects privat Network from unauthorized access

Restricts access to or from local machines

Firewalling based on rules

• accept

• deny

• reject

Rules consists of source and destination IP address and Port (TELNET, FTP, HTTP ...)

EXTREMLY HARD TO CONFIGURE

Firewall

Firewall

HTTP

TELNET

NETWORK A NETWORK B

Masquerading

Is located on the same position as the Firewall Only one public IP address needed for whole

private Network Often works together with Firewalls on the same

machine Exchanges local IP address with the public address

192.168.1.x

PublicNetwork

Masquerading

192.168.1.x

212.21.117.3

Section

VRRP

OSI Layer Model

Ethernet

IP

ARP

IP Routing

Higher Layer Protocols

VRRP

Provides Router Redundancy transparent to hosts

All Router must reside on the same Network

The machine with the highest priority becomes VRRP mastership

Machines with lower priority are VRRP slaves

Up to 254 machines for redundancy

The master broadcasts VRRP packets

If no VRRP packet is received within a defined time, the Slave with the highest priority takes mastership and starts to send VRRP packets and listens on the specified IP address

Virtual Router Redundancy Protocol (VRRP)

VRRP

Simple 1+1 redundancy

MasterSlave

GW: Master GW: Master

VRRP: MasterVRRP: Master

Section

ATM Vision Network Setup

OSI Layer Model

Ethernet

IP

ARP

IP Routing

Higher Layer Protocols

VRRP

IP Network Settings

Enable networking:

sysconf net enable

Startup Ethernet Interface:

sysconf net <Interface> <IP address> netmask <Mask> up

<Interface>: eth0 = Ethernet 1 eth1 = Ethernet 2

IP Network Settings

Set route to other local networks:sysconf route add –net <IP address> netmask <Mask> gw <Gateway>

Inband Management

Enable Classical IP (CLIP):

sysconf clip enable

Enable IP forwarding to other interfaces:sysconf net ipforward enable

Inband Management

Add CLIP destination to routing table:

sysconf atmarp add <Dest. IP address> <VPI>.<VCI>

Configure CLIP interface:sysconf net <Interface> <IP address> netmask <Mask> up

Create CLIP interface:sysconf clip interface <Index> enable

<Interface>: clip<Index>

Inband Management

CLIP QoS parameter:

sysconf clip interface <Index> qos <QOS|default>

<QOS> = <class>,<type>:<common list>,tx:<list>,rx:<list> <class> = ubr | cbr <type> = aal0 | aal5 <common list> = <list> valid for tx and rx <list> = pcr=rate | max_pcr=rate | min_pcr=rate |

sdu=size | max_sdu=size

VRRP

root@Karlsruhe:/> sysconf vrrp ?usage: sysconf vrrp sysconf vrrp show sysconf vrrp <VRID> disable sysconf vrrp <VRID> priority <priority> sysconf vrrp <VRID> advertise <advertise interval> sysconf vrrp <VRID> preempt enable|disable sysconf vrrp <VRID> auth none|<password> sysconf vrrp <VRID> IP <IP-Address> { <IP-Address> } sysconf vrrp <VRID> monitor disable|<IP-Address> <TTL> <icmp|eth0|eth1>root@Karlsruhe:/>

VRRP Parameter:

<VRID> = VRRP ID (identifies the VRRP Network)priority = Router priority on the VRRP ID <0..255>. Default: 255 = VRRP masteradvertise = Time interval (in sec.) between two VRRP protocol packets. Timeout after

3 * advertise interval preempt = Allows slave to take over VRRP mastership from slaves with lower priority.

VRRP master with priority = 255 always takes mastershipauth = Authentication necessary (with password) or notIP = IP-Address(es) to protectmonitor = Allows additional monitoring on further connections (ETH0, ETH1 or ATM).

Monitoring on ETH0 and ETH1 is only supported on ATM Vision.

Checking Connectivity

Check IP (Ethernet) connection:

ping <IP address>

Tracing route to destination:

traceroute <IP address>

Check ATM connection:

oam <Interface> <VPI> [VCI] <seg|end>-<loopback|ais|rdi>

Checking Connectivity

The last ressort:

tcpdump -i <Interface> -n [-vv]

Establish remote connection:

telnet <IP address>

Section

Practice

OSI Layer Model

Ethernet

IP

ARP

IP Routing

Higher Layer Protocols

VRRP

ATM Vision Network Setup

Hands On: IP Network

Name:

IP address:

Netmask:

Name:

IP address:

Netmask:

Name:

IP address:

Netmask:

Hub

Name:

IP address:

Netmask:

EthernetATM

IP Range: 192.168.x.x

Hands on: IP, ATM and VRRP

ATM

IP Range: 192.168.x.x

Ethernet

Hands on: IP and CLIP over SVC

Name:

IP address:

Netmask:

Name:

IP address:

Netmask:

Name:

IP address:

Netmask:

Name:

IP address:

Netmask:

EthernetATM

IP Range: 192.168.x.x

SD

Catalyst8500

Power Supply 0CISCO YSTEMSS Power Supply 1

SwitchProcessor

SERIES