lan ip technologies
DESCRIPTION
Summary of LAN technologies used in the industryTRANSCRIPT
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LAN Technologies
Router
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802.3 802.5 802.11 ISO9314
CSMA/CDMAC
Token RingMAC
WLANMAC
FDDIMAC
Logical Link Control (LLC)802.2
Phy
Dat
a Li
nkProtocols of the network layer
802.4
Token BusMAC
IEEE Layer 2 protocols
MAC … Media Access Control
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SIEMENSNIXDORF SIEMENSNIXDORF SIEMENSNIXDORF SIEMENSNIXDORF
Ethernet FrameHeader contains MAC Addresses
Ethernet FrameHeader contains MAC Addresses
DA=4
1 432
Oh!My address.
I‘ll read the packet
Oh!My address.
I‘ll read the packet
Nothing to do with me.Not my
MAC address
Nothing to do with me.Not my
MAC address
Data transmission within an Ethernet LAN
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Ethernet Frame (native frame)
General overhead:The Ethernet frame consists of a preamble with 8 bytes, the minimum frame size of 64 bytes and an interframe gap with 12 bytes. The following diagram is an example:
Preamble SDDestination
AddressSource Address
Type DataFrameCheck
Sequence
7 Bytes 1 Byte 6 Bytes 6 Bytes 2 Bytesvariable length46 to 1500 Bytes
64 Byte ≤ frame size ≤ 1518 Byte
4 bytes
Ethernet - FrameEthernet - Frame
InterframeGap
12 bytes
Result:84 byte for a minimal frame – 1538 byte for maximal frame length Preamble, Start delimiter (SD) and interframe gap are negligible for long packets, but a significant contribution in case of short packet length (e.g. around 100 bytes for VoIP)
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Ethernet Frames and MAC Addressing
Destination MAC
SourceMAC
TypeField
Checksum
Data of Layers 3 to 7
6 Bytes 6 Bytes 2 By 4 Bytes
The Type Field: specifies, which Layer 3 Protocol is contained
The Checksum (CRC) secures both addresses, type field and data
up to 1500 Bytes
Ethernet Frame
MAC-Address : (Media Access Control)Address on Layer 2 most commonly used on Ethernet, 6 Bytes long,linked to Hardware, worldwide unique
MAC-Broadcast addresses all stations on a LAN (Address = ff:ff:ff:ff:ff:ff)
MAC-Multicast addresses all stations with a particular propertye.g. all switches supporting a particular protocol
Data Link
Network
Transport
Session
Presentation
Application
Physical
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Ethernet Switching 1/2
11 22 33 44
SAT – Table or MAC-Address-Table
(SAT = Source-Address-Table)
Port Address
1
2
3
4
08:00:06:00:00:0A 08:00:06:00:00:0B 08:00:06:00:00:0C 08:00:06:00:00:0D
Src: 08:00:06:00:00:0ADst: 08:00:06:00:00:0C
Src: 08:00:06:00:00:0ADst: 08:00:06:00:00:0CSrc: 08:00:06:00:00:0CDst: 08:00:06:00:00:0A
Src: 08:00:06:00:00:0CDst: 08:00:06:00:00:0A
SAT – Table or MAC-Address-Table
(SAT = Source-Address-Table)
Port Address
1 08:00:06:00:00:0A
2
3
4
SAT – Table or MAC-Address-Table
(SAT = Source-Address-Table)
Port Address
1 08:00:06:00:00:0A
2
3 08:00:06:00:00:0C
4
SAT – Table or MAC-Address-Table
(SAT = Source-Address-Table)
Port Address
1 08:00:06:00:00:0A
2 08:00:06:00:00:0B
3 08:00:06:00:00:0C
4 08:00:06:00:00:0D
????<unknown><unknown><unknown><unknown>
flooding
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Ethernet Switching 2/2
• The Forwarding Table is learnt dynamically from the packet’s source addresses
• If the destination MAC address is not known, the packet is “flooded”, which means it is forwarded to all ports
• If the destination MAC address is known, the packet is only forwarded to the port where the address has been learnt
• Broadcast (eg ARP) and Multicast (without IGMP Snooping) messages are always flooded
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IEEE 802.3 Frame Capture
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The LLC (Logical Link Control) sublayer
Media Access Control
hardware dependent
Logical Link Control
hardware independent
NetworkNetworkNetwork
Data LinkData LinkData Link
PhysicalPhysical
LLCLLCLLC
MAC FrameMAC Frame 802.2 LLC802.2 LLC802.2 LLC Layer 3 dataLayer 3 data
MACMAC
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DSAP SSAP Control Field Data
1 Byte 1 Byte 1Byte variabel
LPDU (IEEE 802.2)
This is the address of a network layer protocol
This partcontains information
The most important SAPs: BPDU 42 Bridge Protocol Data Unit (Spanning Tree) Banyan BC Banyan Vines IBMNM F4 IBM Network Management IP 06 Internet Protocol ISO FE International Standard Organization NetBIOS F0 Network Basic I/O System Novell E0 Novell (NetWare) RPL F8 Remote Program Load SNA 04, 05 , 08, 0C Systems Network Architecture SNAP AA Sub Network Access Protocol Global FF Broadcast Null 00 IBM SAP Negotiation They are inserted into the DSAP/SSAP Octet
LPDU (LLC Protocol Data Unit)
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PreambleFrameDeli-meter
DestinationAddress
SourceAddress
Length Data Checksum
DataControlField
SSAPDSAP
Now, the service access point (SAP) defines...
... which protocol isincluded here
Protocol-ID/Organization = 0
Control FieldLLC-Type 1
SSAP0x AA
DSAP0x AA
Ether-Type(e.g. ARP 0x 806)
Data
Now, the SAP defines...
... that a SNAP header follows...
... and the header defines which protocol follows
and with SNAP:
standard encapsulation:
Ethernet Frame (IEEE 802.3, 802.2) with LLC
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L2-Switch
The switch and I can talk 100 Mbitsper second!
1 Gbps one way and 1 Gbps the other way, that sums up to 2 Gbps….
But I‘m on full duplex. The switch and I can use the full 1Gbps link capacity at the same time.
L2-Switch
Yes, that‘s called ‚California Count‘. It‘s a popular way to express switching capacities. Instead of saying you can switch 320 Gbps Full Duplex you could say you have 640 Gbps switching capacity.
Full-duplex operation is restricted to point to poi nt linksconnecting exactly two stations.
But if we talk at the same time, we‘re in trouble*. You‘re on a half duplex link.
*requires CSMA/CD
Half Duplex – Full Duplex
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Ethernet Auto -Negotiation
• Twisted-pair Auto-negotiation defines a standard to address the following:– Provide easy, plug-and-play upgrades from 10 Mbps, 100 Mbps, and 1000
Mbps as the network infrastructure is upgraded– Prevent network disruptions when connecting mixed technologies such as
10BaseT, 100BaseTX and 1000BaseT– Accommodate future PHY (transceiver) solutions– Allow manual override of auto-negotiation– Support backward compatibility with 10BaseT– Provide a parallel detection function to recognize 10BaseT and 100BaseTX
non-auto-negotiation devices– Mandatory auto-negotiation for 1000BaseT– Configure master and slave modes for the PHY
• Fiber optic Auto-negotiation– Only defined for the 1000BASE-X fiber optic media system– Used by the link partners on a Gigabit Ethernet fiber optic link to determine
which modes of operation they support in common (e.g., full-duplex, PAUSE operation)
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Virtual LAN (VLAN)Broadcast Domain Separation
VLAN1 -> Broadcast Domain
VLAN2 -> Broadcast Domain
VLAN3 -> Broadcast Domain
L2-Switch L2-Switch
Several logical networks (VLAN) share one physical media (LAN)
VLANs are used for customer separation
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10.0.0.254/24 10.0.1.254/24
IP 10.0.0.1/24GW 10.0.0.254
IP 10.0.1.1/24GW 10.0.1.254
IP 10.0.0.2/24GW 10.0.0.254
IP 10.0.1.2/24GW 10.0.1.254
Virtual LAN 1/2
11 22 33 44
08:00:06:00:00:01 08:00:06:00:00:02 08:00:06:00:00:03 08:00:06:00:00:04
SAT – Table (MAC-Address-Table)
Port Address VLAN-ID
1 08:00:06:00:00:0A 1
2 08:00:06:00:00:0B 2
3 08:00:06:00:00:0C 1
4 08:00:06:00:00:0D 2
SAT – Table (MAC-Address-Table)
Port Address VLAN-ID
1 08:00:06:00:00:0A 1
2 08:00:06:00:00:0B 2
3 08:00:06:00:00:0C 1
4 08:00:06:00:00:0D 2
5 08:00:06:00:00:10 1,2
55
08:00:06:00:00:10
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Virtual LAN 2/2
• Switch ports are logically grouped with the help of VLANs (PVID)
• Each group behaves like an individual switch
• Inter-VLAN communication is only possible with a router
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Ethernet FrameVLAN
Additional Bytes:In a VLAN-tagged frame 4 bytes are added between the Type-Field and the Data-Field
Preamble SDDest.
AddressSourceAddress
DataFrameCheck
Sequence
7 Bytes 1 B. 6 Byte. 6 Byte 2 B.46 to 1500 Bytes 4 bytes
Ethernet II – Frame (with VLAN tag)Ethernet II – Frame (with VLAN tag)
InterframeGap
12 bytes
TypeTCI
TPID (Ether type)Tag protocoll identifier
TCITag Control Information
3 1 12Defines type of 802.1q tag
2 B. 2 B.
User priority CFI (Cannonicalformat identifier)
VLAN ID(n <= 4094)
Total Ethernet Frame Size68...1522 Byte(without Preamble, SD and Interframe Gap)
TPIDTPID TCI
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Is forwarded to any port (except the receiving port)
The problem is solved by STP = Spanning Tree Protocol
Ethernet Protection Mechanisms 1/2
An incoming Ethernet packet with unknown destination…
So it‘s obvious that Loops lead to problems (a.k.a. “Broadcast storm”).
Here it‘s also „nice“ thatEthernet packets have no time to live counter
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Ethernet Protection Mechanisms 2/2
STP blocks the network at certain links
So loops are avoided
This can also be used for protection – if another link goes down, the block is released
STP Variants:- STP (tens of seconds protection switching time)- RSTP (Rapid STP, around one second): the protection links are pre-calculated by the switches: Faster, but manual configuration of switches required, some configurations required (root bridge, backup root bridge)- PV(R)STP: RSTP per VLAN- MSTP: RSTP per VLAN-Groups, scales much better than RSTP / PV(R)STP
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Other Spanning Tree Operational Modes
• Spanning Tree – 802.1D• Rapid Spanning Tree – 802.1w
- Faster than 802.1D due to better Topology Change m echanisms (reconfiguration within 1s)
• Per VLAN Spanning Tree (PVSTP)- Uses same mechanism as 802.1D but independent for each VLAN- Scalability problem (~ 128 VLANs at a time)
• Per VLAN Rapide Spanning Tree (PVRSTP)- Uses same mechanism as 802.1w but independent for each VLAN- Scalability problem (~ 128 VLANs at a time)
• Multiple Spanning Tree – 802.1s- Same recovery time as 802.1w- Allows grouping of VLANs into regions instances wit hin a region - Only one BPDU per region is necessary
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Tagged Port
in order to reduce the number of Switch-to-Switch and Switch-to -Router connections additional information (tags) for the VLAN association is inserted into the Ethernet frame.
A “tagged” port is part of several VLANs and Broadcast Domains.
12
12
ports are assigned simultaneous
frame with tag1
2