Datenkommunikation 384.081 - SS 2007 Datenkommunikation 384.081 - SS 2007 L07 - Ethernet Evolution L07 - Ethernet Evolution The Beginning • initial idea: shared media LAN – bus structure, CSMA/CD was access method – coax cable, transmission rate up to 10 Mbit/s – half-duplex transmission (two physical wires e.g. coax) The Ethernet Evolution collision domain From 10Mbit/s to 10Gigabit/s Ethernet Technology From Bridging to L2 Ethernet Switching and VLANs © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 3 Agenda Enlarging the Network • Ethernet Evolution • VLAN • High Speed Ethernet – Introduction – Fast Ethernet – Gigabit Ethernet – 10 Gigabit Ethernet repeater as signal amplifier used to enlarge the network diameter but no network segmentation !!! still one collision domain !!! © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 2 © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 4 © 2007, D.I. Manfred Lindner © 2007, D.I. Manfred Lindner Page 07 - 1 Page 07 - 2 Datenkommunikation 384.081 - SS 2007 Datenkommunikation 384.081 - SS 2007 L07 - Ethernet Evolution L07 - Ethernet Evolution Multiport Repeater Structured Cabling (2) • demand for telephony-like point-to-point cabling represents four CU wires 2 for Tmt, 2 for Rcv using Twisted Pair wires Server Farm (e.g. 10BaseT) – based on structured cabling standard represents two FO wires – 10BaseT as new Ethernet type to support this demand e.g. 10BaseF – four physical wires (2 for tmt, 2 for rcv) • network stations are connected star-like to a 10 Base F multiport repeater – multiport repeater is called “hub” • hub simulates the bus: "CSMA/CD in a box" • only half-duplex 10 Base T – only one network station can use the network at a given Client-PCs time, all others have to wait © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 5 © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 7 Structured Cabling (1) Bridging • simple physical amplification with repeaters became insufficient Multiport Repeater, “Hub” “CSMA/CD in a box” – with repeaters all nodes share the given bandwidth – the whole network is still one collision domain – -> technology moved toward layer 2 • bridges segment a network into smaller collision domains – store and forward technology (packet switching) – the whole network is still a broadcast domain – Spanning Tree provides a unique path between each two 10 Base T devices and avoids broadcast storms © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 6 © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 8 © 2007, D.I. Manfred Lindner © 2007, D.I. Manfred Lindner Page 07 - 3 Page 07 - 4 Datenkommunikation 384.081 - SS 2007 Datenkommunikation 384.081 - SS 2007 L07 - Ethernet Evolution L07 - Ethernet Evolution Network Segmentation with Bridges Switching (2) collision domain on point-to-point link reduced to a single link collision domain on Bridge Broadcast Domain shared media (only half duplex possible) Switch Collision Domains © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 9 © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 11 Switching (1) Switching (3) • "switching" means fast transparent bridging full duplex on point-to-point links collision domain on – implemented in hardware shared media (only half – also called Layer 2 (L2) switching or Ethernet switching duplex possible) • multiport switches allow full duplex operation on point-to-point links – no need for collision detection (media access control) on a link which is shared by two devices only • network station <-> switch port • switch <-> switch • multiport switches replaces multiport repeaters – a collision free Ethernet can be built, if network consists of point-to-point links only © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 10 © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 12 © 2007, D.I. Manfred Lindner © 2007, D.I. Manfred Lindner Page 07 - 5 Page 07 - 6 Datenkommunikation 384.081 - SS 2007 Datenkommunikation 384.081 - SS 2007 L07 - Ethernet Evolution L07 - Ethernet Evolution Switching (4) Switching (6) full duplex everywhere = collision free Ethernet LAN Server 100 Mbit/s 100 Mbit/s Server 1 Gbit/s 1 Gbit/s Flow Control possible Clients Broadcast Domain 10 Mbit/s © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 13 © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 15 Switching (5) Redundant Topology L2 Switching PC3 PC6 • L2 switches can connect Ethernets with 10 represents four CU wires 2 for Tmt, 2 for Rcv Mbit/s, 100 Mbit/s or 1000 Mbit/s for example (e.g. 10BaseT) – clients using 10 Mbit/s either half duplex on shared media MAC D MAC F p1 p2 represents two FO wires or full duplex on point-to-point connection with switch e.g. 10BaseF – server uses 100 Mbit/s, full duplex, point-to-point S3 connection with switch t1 t2 – note: multiport repeater is not able to do this ! t1 Trunks t1 • L2 switch as packet switch operates with t2 t2 asynchronous TDM S1 S2 p1 p2 p1 p1 p2 – congestion can be avoided by using a new MAC based MAC A MAC B MAC E MAC C flow control (pause command) PC1 PC4 PC5 PC2 © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 14 © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 16 © 2007, D.I. Manfred Lindner © 2007, D.I. Manfred Lindner Page 07 - 7 Page 07 - 8 Datenkommunikation 384.081 - SS 2007 Datenkommunikation 384.081 - SS 2007 L07 - Ethernet Evolution L07 - Ethernet Evolution Spanning Tree Applied Agenda PC3 PC6 • Ethernet Evolution • VLAN MAC D MAC F p1 p2 • High Speed Ethernet S3 – Introduction – Fast Ethernet t1 F t2 F (Forward) – Gigabit Ethernet t1 F Trunk t1 B (Blocked) – 10 Gigabit Ethernet t2 F t2 S1 S2 p1 p2 p1 p1 p2 MAC A MAC B MAC E MAC C PC1 PC4 PC5 PC2 © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 17 © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 19 Switching Table (L2) Virtual LANs (1) Switching Table S3 pro VLAN PC3 PC6 • today's work-groups are expanding over the MAC-Addr. Port/Trunk D p1 whole campus in case of local environment MAC D MAC F F p2 p1 p2 • users of one workgroup should be kept A,B,C,E t1 separated from other workgroups S3 Switching Table S1 pro VLAN – because of security reasons they should see there MAC-Addr. Port/Trunk t1 t2 Switching Table S2 pro VLAN necessary working environment only A p1 MAC-Addr. Port/Trunk B p2 t1 t1 E p1 • end-systems of one workgroup should see D,F t1 t2 t2 C p2 C,E t2 broadcasts only from stations of same A,B,D,F t2 S1 S2 p1 p2 p1 p1 p2 workgroup MAC A MAC B MAC E MAC C • the network must be flexible – to adapt continuous location changes of the end- PC1 PC4 PC5 PC2 systems/users © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 18 © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 20 © 2007, D.I. Manfred Lindner © 2007, D.I. Manfred Lindner Page 07 - 9 Page 07 - 10 Datenkommunikation 384.081 - SS 2007 Datenkommunikation 384.081 - SS 2007 L07 - Ethernet Evolution L07 - Ethernet Evolution Virtual LANs (2) VLAN Assignment • base idea of VLAN: • a station may be assigned to a VLAN – multiplexing of several LANs via same infrastructure – port-based (switches and connection between switches) • fixed assignment port 4 -> VLAN x • today's switches got the ability to combine • most common approach several network-stations to so-called "Virtual • a station is member of one specific VLAN only LANs“ – MAC-based • MAC A -> VLAN x – separate bridging/switching table maintained for every • allows integration of older shared-media components and single VLAN automatic location change support – separate broadcast handling for every single VLAN • a station is member of one specific VLAN only • each Virtual LAN is its own broadcast domain – protocol-based – separate Spanning Tree for every single VLAN • IP-traffic, port 1 -> VLAN x • note: IEEE 802.1w specifies a method to share one Rapid • NetBEUI-traffic, port 1 -> VLAN y Spanning Tree among all VLANs • a station could be member of different VLANs © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 21 © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 23 VLAN Example Virtual Trunks - VLAN tagging VLAN A • switches must be connected via VLAN-trunks on A4 A5 A1A2 A3 which each particular VLAN-frame is "tagged" (marked) with an identifier – examples for tagging standards: • IEEE 802.10 (pre 802.1Q temporary solution) • ISL (Cisco) Table VLAN A Table VLAN A • IEEE 802.1Q Table VLAN B Table VLAN B • so switches can distinguish between several VLANs and manage their respective traffic B1 B2 B3 B4 B5 VLAN B © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 22 © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 24 © 2007, D.I. Manfred Lindner © 2007, D.I. Manfred Lindner Page 07 - 11 Page 07 - 12 Datenkommunikation 384.081 - SS 2007 Datenkommunikation 384.081 - SS 2007 L07 - Ethernet Evolution L07 - Ethernet Evolution 802.1Q VLAN Tagging 1 VLAN Operation (1) 802.3 802.2 LLC VLAN A A4 A5 802.1Q A1A2 A3 preamble DA SA length DSAP SSAP Ctrl data FCS Fields A1 -> A3 A5 -> broadcast 2 Byte 2 Byte TPID … Tag Protocol Identifier TPID TIC TCI … Tag Control Information 0x8100 trunk untagged frames 3 Bit 1 Bit 12 Bit UP CFI VID B1 -> B5 UP … User Priority note: With tagging Ethernets maximal CFI … Canonical Format Identifier frame length = 1522, minimal frame VID … VLAN Identifier B1 B2VLAN B B3 B4 B5 length = 68 © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 25 © 2007, D.I. Manfred Lindner Ethernet Evolution, v4.6 27 802.1Q VLAN Tagging 2 VLAN Operation (2) Ethernet V2 VLAN A A4 A5 802.1Q A1A2 A3 preamble DA SA type data FCS Fields 2 Byte 2 Byte A1 -> A3 tag VLAN A TPID … Tag Protocol Identifier A5 -> broadcast TPID TIC TCI … Tag Control Information A5 -> broadcast 0x8100 B1 -> B5 3 Bit 1 Bit 12 Bit UP CFI VID tag VLAN B UP … User Priority note: With tagging Ethernets maximal CFI … Canonical Format Identifier frame length = 1522, minimal frame VID … VLAN Identifier B1 B2VLAN B B3 B4 B5 length = 68 © 2007, D.I.