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

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

OSI and Internet Protocol Suite FTP, Telnet, SMTP, SNMP ARP, RARP Presentation IP ICMP Ethernet OSI Reference ModelInternet Protocol Suite NFS XDR PRC Application TCP UDP Session Transport Network Data Link Physical

LAN Layer and the OSI Reference Model Data Link Layer MAC Sublayer Physical Layer Ethernet IEEE BaseT Token Ring/IEEE FDDI LLC Sublayer IEEE OSI LayersLAN Specifiaction

Section Ethernet OSI Layer Model

Ethernet Frame Preamble Source Address FCS Destination Address TypeData Field Length, In Bytes FCS = Frame Check Sequence MAC Address: IP Data : 00 : a3 : 25 Vendor specific Vendor ID 00 : 50 : 66 IP Header

Section IP (Internet Protocol) OSI Layer Model Ethernet

IP Packet VersionIHLType of ServiceTotal Length IdentificationFlagsFragment offset Time to LiveProtocolHeader 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 C0A C Hex: Dec.: Bin.:...

Network Example

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 MAC address MAC address MAC address MAC address MAC address MAC address MAC address MAC address MAC address MAC address IP: MAC: 00:25:12:34:F2:A3 IP: MAC: 00:25:12:11:BB:C1 IP: MAC: 01:A1:23:8A:45:01 MAC address MAC address

Section IP Routing OSI Layer Model Ethernet IP ARP

Subnetting With Netmask IP address „ANDED“ with netmask splits net into network and subnet portion IP Address: Logical AND with Netmask:... Network Subnet Results in Subnet number: „AND“

Network Example Router

Special IP Addresses Network: x Netmask: Subnet number: Subnet broadcast: Example: Local host: Multicast groups: Experimental:

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 table Routing 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 Datagram Protocol (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 HTTP TELNET NETWORK ANETWORK 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 x Public Network Masquerading x

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 VRRP: 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 netmask up : eth0 = Ethernet 1 eth1 = Ethernet 2

IP Network Settings Set route to other local networks: sysconf route add –net netmask gw

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. Configure CLIP interface: sysconf net netmask up Create CLIP interface: sysconf clip interface enable : clip

Inband Management CLIP QoS parameter: sysconf clip interface qos =, :,tx:,rx: = ubr | cbr = aal0 | aal5 = valid for tx and rx = pcr=rate | max_pcr=rate | min_pcr=rate | sdu=size | max_sdu=size

VRRP sysconf vrrp ? usage: sysconf vrrp sysconf vrrp show sysconf vrrp disable sysconf vrrp priority sysconf vrrp advertise sysconf vrrp preempt enable|disable sysconf vrrp auth none| sysconf vrrp IP { } sysconf vrrp monitor disable| VRRP Parameter: = VRRP ID (identifies the VRRP Network) priority = Router priority on the VRRP ID. Default: 255 = VRRP master advertise = 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 mastership auth = Authentication necessary (with password) or not IP = IP-Address(es) to protect monitor = 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 Tracing route to destination: traceroute Check ATM connection: oam [VCI] -

Checking Connectivity The last ressort: tcpdump -i -n [-vv] Establish remote connection: telnet

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: Ethernet ATM IP Range: x.x

Hands on: IP, ATM and VRRP ATM IP Range: 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: Ethernet ATM IP Range: x.x