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Network Technologies - Switching

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  1. Network Technologies - Switching

  2. Agenda • What is switching? • How does it work? • Ethernet Switches • Areas of application for switches

  3. Switch A B Video Switch Switch Digital Switching Network Telephone Switch (Exchange) Switches (1)

  4. Switches (2) CP6923 Switch 24 port GbE switch Options: • 4 GbE ports front; 20 ports rear • 2x 10 GbE front, 24 ports rear • Ethernet • Local Area Networks (LAN) • What does it switch?

  5. Higher Protocol Layers IP Internetwork LLC/SNAP Router Network LAN MAC Link Host LAN-PHY Physical LAN Switch/Hub Host Local Area Networks (LAN) LAN, Protocols, Layer 2, Layer 3? Source: Harald Orlamünder

  6. Local Area Network - Protocols ISO/OSI Model ETHERNET (IEEE 802 Reference Model) 7 Application Presentation 6 Higher protocol layers 5 Session 4 Transport Link Service Access Point Network 3 LSAP 2b Logical Link Control (LLC) Link 2 Medium Access Control (MAC) 2a 1 Physical Physical 1

  7. But what does it switch? Local Area Network – IEEE Standards Logical Link Control (802.2) 2 Link Bridging (802.1) Management (802.1) Ethernet MAC (802.3) Wireless MAC (802.11) … 1 PHY LAN-PHY (802.3) Wireless MAC PHY (802.11) … • Also available: IEEE reference model for implemetion • Different physical layers (Coax, Copper Pairs, optical fibre), modes (half duplex, full duplex) and Speeds • Classification e.g. 10 BASE-5, 100 BASE-FX, … • To be implemented on switch

  8. How does it work? Concepts for switching

  9. (2) Load file (3) Print document (1) Load web-site Home Network Host Host LAN Switch/Hub Network Printer Router& DSL-Modem How do the scenarios work? Internet Web Server

  10. Adressing in the Home Network 192.168.178.21 00:13:02:39:e5:f7 Host 192.168.178.22 00:0a:95:d1:52:30 Host LAN Network Printer Switch/Hub 192.168.178.23 00:80:77:31:b6:45 192.168.178.1 00:04:0e:73:3f:3d Router& DSL-Modem • IP addresses assigned by the router (DHCP) • MAC addresses built in by manufacturer of network interface IP-Address (L3) MAC Address (L2)

  11. Request message to 100:0a:95:d1:52:30 How a Hub works (1) – Request 100:13:02:39:e5:f7 Host 100:0a:95:d1:52:30 Host LAN Network Printer Hub 100:80:77:31:b6:45 100:04:0e:73:3f:3d Propagate request to all ports • Everything is based on MAC addresses • Hub = multiport repeater

  12. Reply message from 100:0a:95:d1:52:30 Can this be done a more clever way? How a Hub works (2) – Reply 100:13:02:39:e5:f7 Host 100:0a:95:d1:52:30 Host LAN Network Printer Hub 100:80:77:31:b6:45 100:04:0e:73:3f:3d Propagate reply to all ports

  13. LAN Segment 1 (local traffic) Traffic between segments Router LAN LAN Segment 2 (local traffic) Host LAN Host From Hubs to Bridges Bridge Ethernet: the first popular serial bus • A Hub “solders” two LAN segments together (propagates messages received to all ports; repeats everything) • A Bridge “bridges” two LAN segments (propagates only messages from one segment intended for the other segment)

  14. Request message to 100:0a:95:d1:52:30 MAC Port 100:13:02:39:e5:f7 2 How a Bridge works (1) – 1st Request 100:13:02:39:e5:f7 Host 100:0a:95:d1:52:30 Host LAN Network Printer Bridge 100:80:77:31:b6:45 100:04:0e:73:3f:3d 1st time: Propagate request to all ports Memorize receiver port & MAC address

  15. Reply message from 100:0a:95:d1:52:30 MAC Port 100:13:02:39:e5:f7 2 100:0a:95:d1:52:30 3 How a Bridge works (2) – Reply 100:13:02:39:e5:f7 Host 100:0a:95:d1:52:30 Host LAN Propagate reply to the right port Network Printer Bridge 100:80:77:31:b6:45 100:04:0e:73:3f:3d A bridge is a hub with memory. Memorize receiver port & MAC address

  16. Message to 100:0a:95:d1:52:30 Way less messages and much safer! How a Bridge works (3) – 2nd Request 100:13:02:39:e5:f7 Host 100:0a:95:d1:52:30 Host LAN Network Printer Bridge 100:80:77:31:b6:45 100:04:0e:73:3f:3d Propagate request to the right port

  17. Hubs, Bridges and Switches Concepts Demo Animation

  18. Conceptual Architecture Input buffer Output buffer processor Ports Ports Memory (switch routing table) How to transmit frames? • Processor: analyse protocol header • Place packet/frame on right output port

  19. Bridge (bus architecture) 100 Mbps in out 100 Mbps 100 Mbps 100 Mbps 100 Mbps Switch 100 Mbps 100 Mbps 100 Mbps 100 Mbps Hubs, Bridges and Switches A Switch is a Bridge with max. line speed between any ports.

  20. Using IP Addresses as host identifiers 192.168.178.21 00:13:02:39:e5:f7 Host 192.168.178.22 00:0a:95:d1:52:30 Host LAN Network Printer Hub/Switch 192.168.178.23 00:80:77:31:b6:45 192.168.178.1 00:04:0e:73:3f:3d ARP (Address Resolution Protocol): Who is 192.168.178.22? • IP Addresses: convenient host identifiers • MAC addresses: used for message delivery

  21. Adress Resolution Protocol (1) 192.168.178.21 00:13:02:39:e5:f7 192.168.178.22 00:0a:95:d1:52:30 Host Host LAN Who is 192.168.178.22 ? Network Printer Hub/Switch 192.168.178.23 00:80:77:31:b6:45 „Who is“ request containing destination IP-Adress

  22. Its me, MAC 100:0a:95:d1:52:30 Protocol Layers IP PHY MAC Adress Resolution Protocol (2) 192.168.178.21 00:13:02:39:e5:f7 192.168.178.22 00:0a:95:d1:52:30 Host Host LAN Network Printer Hub/Switch 192.168.178.23 00:80:77:31:b6:45 Host replies with MAC adress • ARP implemented in hosts • resolves IP adresses into MAC addresses • MAC addresses used for message delivery

  23. ARP Demo • A nice demo of ARP is available at http://www.oxid.it/downloads/apr-intro.swf • Remarks: • ARP is a so called “stateless” protocol, it is not aware whether different requests or replies belong to the same transaction or not. • The demo also shows, how ARP may be misused to introduce a sniffer or “man in the middle” to eavesdrop or manipulate data streams • There are ways to protect networks, but awareness of security issues is always needed. • Local Demo: C:\Dokumente und Einstellungen\stephru\Desktop\Seminar\resources\ARP_Demo\apr-intro.swf

  24. Switching & Routing Network of switches (L2) Network of Routers (L3) Network of relations (application level)

  25. Switching and Routing Host Host Switching • Local area network • Layer 2 protocols LAN Port No MAC Address Switch/Hub Network Printer Router& DSL-Modem IP Address Port No Routing • Wide area network • Layer 3 protocols Internet Web Server

  26. Managed Switch/ L3 Switch • Managed Switch: • has IP address to connect management terminal (not needed for message delivery); • Management via CLI, SNMP, TELNET • Ethernet/Bridging protocols (Layer 2) • Link aggregation (802.3ad), VLANs (802.1Q), Spanning Tree (802.1D, 802.1w), QoS (802.1p), Flow control (802.3x), GVRP, GMRP • IP routing protocols (Layer 3) • OSPFv2, RIPv2, VRRP, IGMP snooping, IPv4 forwarding, DiffServ, ARP, ICMP • DCHP Client/Server: receive/distribute local IP addresses

  27. Protocol Layers IP PHY MAC Ethernet- and IEEE 802.3-Frames Ethernet-Frame DestinationAddress SourceAddress Type Information (IP-Packet) CRC 6 6 2 46 ... 1500 4 IEEE 802.3 Frame DestinationAddress SourceAddress Len LLC/SNAP Information (IP-Packet) CRC 6 6 2 8 38 ... 1492 4 MAC DSAP SSAP crtl. Org.Code Type 1 1 1 3 2 LLC SNAP Source: Harald Orlamünder

  28. Virtual LAN • Classify ports and Ethernet frames into groups • Segmentation into separate and independent LANs • Controlled environment with reduced complexity VLAN1 LAN VLAN2 VLAN3 Trunk

  29. VLAN – Frame Format QTag Prefix DestinationAddress SourceAddress Tag Type Tag Control Type Data PAD FCS 6 octet 6 octet 2 octet 2 octet 2 octet 46 ... 1500 octet 4 octet Priority ID CFI VLAN-ID CFI Canonical Format Identifier FCS Frame Check Sequence PAD Padding 3 Bit 1 Bit 12 Bit Source: Harald Orlamünder

  30. Switched Networks • Local Area Networks • Home Networks • Corporate Networks • Industry Automation • Transport • Medical • But also: • CPCI Systems according to PICMG 2.16 • Ethernet in the backplane! • ATCA and mTCA systems CP6923

  31. Areas of Application Communications Indutrial Automation Tansport Medical

  32. Session Control and Media Processing Video/Audio On demand Life TV/ local TV • Media Server • announcements • IVR • conferences • voice mail • customised tunes • streaming media • trunking gateways PSTN Media Server Trunking GW/ Signalling Gateway Call Server/ Gateway Controller IP Network (Carrier) • Call Server • control call sessions (SIP/H.323 call control) • control Media Server & Gateways PLMN Trunking GW

  33. CPCI User Agents for Conformance & Load Tests CP-ASM10-PSB CP6923 Switch (Option) 14 slot 10U CPCI chassis PICMG 2.16 compliant 19“ wide, 285 mm deep 4 power supplies (200W each) for 120/230VAC 600 calls per second per CP6012 CP6012 CPU Blade Intel Core Duo CPU @1.66GHz 1 GB RAM (Option: up to 4GB) 40 GB 2.5“ SATA HDD on board 2x GbE on Front Panel 2x GbE on backplane 24 port GbE switch Options: 4 GbE ports front; 20 ports rear 2x 10 GbE front, 24 ports rear

  34. Industrial Ethernet • Many field bus systems will move to Ethernet (Industrial Ethernet) • Requirements • Low latency • Distributed systems • Remote monitoring & control • Areas of application • Process control • Facility control • Communication Technology

  35. Transport • Entertainment systems • Announcements • Video surveillance • Replacement of field bus systems

  36. Medical • Image Processing • Image sources (e.g. digital radiography) • Pre & Post-Processing • Archives • Workstations • All connected over Ethernet Networks • Processors • Ethernet connectivity • CPUs, DSPs • multi-processor • Communication technology (VoIP)

  37. Recommeded Reading Industrielle Netze A. Bormann, I. Hilgenkamp, Hüthig, 2005, ISBN 3778529501 (in German) Recommendation: Paket-basierende Kommunikationsprotokolle Harald Orlamünder, Hüthig Telekommunikation, 2004, ISBN 3826650468 (in German)

  38. The End Switching Technologies