L6: Network Hardware and Software ECE 544: Computer ...

L6: Network Hardware L6: Network Hardware and Softwareand Software

ECE 544: Computer Networks IIECE 544: Computer Networks IISpring 2009Spring 2009

Seskar (at) Seskar (at) winlabwinlab (dot) (dot) rutgersrutgers (dot) edu(dot) edu

Network Hardware BasicsNetwork Hardware Basics

StandardsStandards

Availability of interoperable equipment from multiple vendors

Prevents a “Tower of Babel” situation Equipment from different vendors will interoperate if it

complies with the standard Alliances and certification bodies assure interoperability

Wi-Fi for 802.11 WiMax for 802.16

Lowers costs to consumers Both through competition and economies of scale

Promotes advancement of technology Vendors constantly strive for competitive advantage through

improved technology and features

IEEE 802 StandardsIEEE 802 StandardsMaintained by IEEE 802 LAN/MAN Standards Committee Maintained by IEEE 802 LAN/MAN Standards Committee

(LMSC):(LMSC): 802.1 Overview, Architecture, Internetworking and Management802.1 Overview, Architecture, Internetworking and Management 802.2 Logical Link Control802.2 Logical Link Control 802.3 Ethernet (CSMA/CD PHY and MAC)802.3 Ethernet (CSMA/CD PHY and MAC) 802.5 Token Ring PHY and MAC802.5 Token Ring PHY and MAC

802.11 Wireless LAN802.11 Wireless LAN 802.12 Demand Priority Access802.12 Demand Priority Access

802.15 Wireless PAN802.15 Wireless PAN 802.16 Broadband Wireless Access802.16 Broadband Wireless Access 802.17 Resilient Packet Ring802.17 Resilient Packet Ring

802.18 Radio Regulatory802.18 Radio Regulatory 802.19 Coexistence802.19 Coexistence 802.20 Mobile Broadband Wireless Access802.20 Mobile Broadband Wireless Access 802.21 Media Independent Handoff802.21 Media Independent Handoff 802.22 Wireless Regional Area Network802.22 Wireless Regional Area Network

IEEE 802 Naming ConventionsIEEE 802 Naming Conventions

Standalone documents either get no letter (IEEE Standalone documents either get no letter (IEEE 802.3) or gets a capital letter (IEEE 802.1D)802.3) or gets a capital letter (IEEE 802.1D)

Document that supplements a standalone document Document that supplements a standalone document gets a lowergets a lower--case letter (IEEE 802.11b)case letter (IEEE 802.11b)

Letters are assigned in sequential order (Letters are assigned in sequential order (a,B,C,d,ea,B,C,d,e ……) ) and uniquely identify both the Working Group Task and uniquely identify both the Working Group Task Force and the actual documentForce and the actual document

Approved standards have IEEE in front while drafts Approved standards have IEEE in front while drafts have P only designation followed by the draft have P only designation followed by the draft number (P802.1p/D9)number (P802.1p/D9)

802.1802.1

802.1B Management802.1B Management 802.1D MAC Bridges802.1D MAC Bridges 802.1E System Load Protocol802.1E System Load Protocol 802.1F Common Definitions for Management802.1F Common Definitions for Management 802.1G Remote MAC Bridging802.1G Remote MAC Bridging 802.1H Bridging of Ethernet802.1H Bridging of Ethernet 802.1Q Virtual Bridged LANs802.1Q Virtual Bridged LANs

TerminologyTerminology

PHY LayerHeader

EthernetHeader

IPHeader

TCPHeader

DataEthernetTrailer

PHY LayerTrailer

TCP Segment

Ethernet Frame

IP Packet

Fast Ethernet Symbol Stream

Source: Seifert “The switch Book”

Bridge (Switch)Bridge (Switch)FrameFrameData LinkData Link

RepeaterRepeaterSymbol StreamSymbol StreamPhysicalPhysical

Router (Switch)Router (Switch)PacketPacketNetworkNetwork

Firewall (Switch)Firewall (Switch)Segment or Segment or MessageMessage

TransportTransport

SessionSession

PresentationPresentation

GatewayGatewayApplicationApplication

InterconnInterconn. Device. DevicePDUPDU

Router Hardware HistoryRouter Hardware History

Mid 1980s (early days):Mid 1980s (early days): Shared LANs interconnected by bridgesShared LANs interconnected by bridges Two port software based routersTwo port software based routers

Late 1980s Late 1980s –– early 1990s (rapid expansion for router market)early 1990s (rapid expansion for router market) Slower than bridges but have much more functionsSlower than bridges but have much more functions ““Route when you can, bridge when you mustRoute when you can, bridge when you must””

Early Early –– mid 1990s (routers as necessary evils)mid 1990s (routers as necessary evils) Hardware based bridges (switches) with wireHardware based bridges (switches) with wire--speed performancespeed performance ““Switch when you can, route when you mustSwitch when you can, route when you must””

Late 1990sLate 1990s Hardware based routers become practicalHardware based routers become practical WireWire--speed routingspeed routing Perception that all traffic can be switchedPerception that all traffic can be switched

DevicesDevices

Repeaters/HubsRepeaters/Hubs Bridges (Layer 2 Switches?)Bridges (Layer 2 Switches?) Routers (Layer 3 Switches?)Routers (Layer 3 Switches?)

CoreCore EdgeEdge

Firewalls, Network Address Translators (Layer 4 Firewalls, Network Address Translators (Layer 4 Switches?)Switches?)

Gateways, Load Balancers (Layer 7 Switches?)Gateways, Load Balancers (Layer 7 Switches?)

Switch/Router HardwareSwitch/Router Hardware

MediaInterface

Link ProtocolController

HeaderProcessing

Port 1 (Line Card)

Port N (Line Card)

…Port 2

Switch Fabric

Processor{s}

RequirementsRequirements

Distributed Data PlaneDistributed Data Plane Packet Processing: Examine L2Packet Processing: Examine L2--L7 protocol information L7 protocol information

(Determine (Determine QoSQoS, VPN ID, policy, etc.), VPN ID, policy, etc.) Packet Forwarding: Make appropriate routing, switching, and Packet Forwarding: Make appropriate routing, switching, and

queuing decisionsqueuing decisions Performance: At least sum of external BWPerformance: At least sum of external BW

Distributed Control PlaneDistributed Control Plane Up to 10Up to 106 6 entries in various tables (forwarding addresses, entries in various tables (forwarding addresses,

routing information etc.)routing information etc.) Performance: on the order of 100 MIPSPerformance: on the order of 100 MIPS

Switch FabricSwitch Fabric

Connects inputs and outputsConnects inputs and outputs Fabric types:Fabric types:

Shared BusShared Bus –– shared backplane with or without DMA shared backplane with or without DMA (first and second generation routers) (first and second generation routers) –– arbitration problemarbitration problem

Shared MemoryShared Memory –– single common memory is shared single common memory is shared between multiple input outputs (typically used in lowbetween multiple input outputs (typically used in low--cost cost devices) devices) –– memory bandwidth problemmemory bandwidth problem

Shared InterconnectShared Interconnect (Crossbar) (Crossbar) –– switching fabric switching fabric provides parallel paths. Scheduler is centralized; routing tableprovides parallel paths. Scheduler is centralized; routing tables s are kept in the line cards (third generation routers) are kept in the line cards (third generation routers) –– multicast multicast problemproblem

QueuingQueuing

Output queuePros:

Simple algorithms Single congestion pointCons:

N inputs may send to the same output; requires N times speedup

Input queuePros:

Simple algorithms Single congestion pointCons:

Must implement flow control

Low utilization due to HoL Blocking

Modern routersModern routers

Combine input buffering with virtual output queues Combine input buffering with virtual output queues (separate input queue per output) and use output (separate input queue per output) and use output bufferingbuffering Solves blocking problemSolves blocking problem Resolves contention and simplifies schedulingResolves contention and simplifies scheduling Can achieve utilization of 1Can achieve utilization of 1 Scales to > 1 Scales to > 1 TbpsTbps

Increases complexity (as well as introduces multiple Increases complexity (as well as introduces multiple congestion points)congestion points)

Table SRAMFwd/Class

TCAMs

RTT Buffer Mem (1GB)+ pointer

SRAM

Distributed Memory Router Line Distributed Memory Router Line CardCard

InputQueuing

ReceiveFwd

Engine

ControlCPU MemControl

LinecardControl

CPU

FabricRe-Assem.

TransmitFwd

Engine

OutputQueuing

L2 Buffering Optics

ToFabric

FromFabric

Framer

RTT Buffer Mem (1GB)+ pointer

SRAM

Table SRAMFwd/Class

TCAMs

512+MB DRAM

From CISCO

Switched LANSwitched LAN

Modern switches Modern switches -- LAN Segmentation taken to the LAN Segmentation taken to the extreme (extreme (microsegmentationmicrosegmentation):): No access contentionNo access contention No collisions (fullNo collisions (full--duplex)duplex) Dedicated bandwidth for each stationDedicated bandwidth for each station No distance reduction per segmentNo distance reduction per segment

Best case capacity (nonBest case capacity (non--blocking switch)blocking switch)

n

portportDataRateCapacity

1

StoreStore--andand--forwardforwardThe frame (The frame (packet,messagepacket,message) is ) is

received completely before received completely before decision is madedecision is made

CutCut--troughtroughTable lookup and forwarding Table lookup and forwarding

decision is made as soon as decision is made as soon as ““DestinationDestination”” has been has been receivedreceived

CutCut--Trough vs. StoreTrough vs. Store--andand--ForwardForward

Absolute latency Absolute latency (not that much affected by the lookup (not that much affected by the lookup process)process)

Problem with output port availabilityProblem with output port availability CutCut--trough is generally not possible for multicast or trough is generally not possible for multicast or

unknown destination unknown destination (all output ports have to be available (all output ports have to be available simultaneously)simultaneously)

Performance RequirementsPerformance Requirements

•In general header inspection and packet forwarding require complex look-ups on a per packet basis resulting in up to 500 instructions per packet

•At 40Gbps processing requirements are > 100 MPPS

largelargesmallsmall

Time per packet [Time per packet [µµs]s]Peak packet rate Peak packet rate [[KppsKpps]]

OverheadOverheadRateRate[Mbps][Mbps]

77760.077760.019440.019440.04860.04860.01953.11953.11214.81214.8303.8303.8195.3195.319.519.5

0.010.010.050.050.210.210.510.510.820.823.293.295.125.1251.2051.20

1327.104 1327.104 [Mbps][Mbps]

331.776 331.776 [Mbps][Mbps]

82.944 82.944 [Mbps][Mbps]

38 38 [Bytes][Bytes]

20.736 20.736 [Mbps][Mbps]

6.912 6.912 [Mbps][Mbps]



0.310.311.221.224.884.8812.1412.1419.5219.5278.0978.09121.44121.441214.401214.40

39,813.12 39,813.12 9953.28 9953.28 2488.32 2488.32 1000.001000.00622.08 622.08 155.52 155.52 100.00100.0010.0010.00

OCOC--768 (40G)768 (40G)

OCOC--192 (10G)192 (10G)

OCOC--48 (2.5G)48 (2.5G)

1000Base1000Base--TT

OCOC--1212

OCOC--33

100Base100Base--TT

10Base10Base--TT

(Optical Carrier (OC-1) is SONET line with payload of 50.112 Mbps and overhead of 1,728 Mbps)

Software Based Software Based ““SwitchingSwitching””1.1. NIC receives the frame, stores it in a buffer, and signals the dNIC receives the frame, stores it in a buffer, and signals the device driver to pick it up.evice driver to pick it up.2.2. Device driver will transfer the packet to the IP stack.Device driver will transfer the packet to the IP stack.3.3. IP stack will check the header and options for correctness and tIP stack will check the header and options for correctness and then check the address; hen check the address;

local packets are passed up to higher layers (or socket abstractlocal packets are passed up to higher layers (or socket abstraction); nonion); non--local packets local packets are passed to IP forwarder.are passed to IP forwarder.

4.4. IP forwarder will decrement the TTL, and consult the routing tabIP forwarder will decrement the TTL, and consult the routing table as to where to le as to where to send the packet (lookup). Tables are constructed by a separate rsend the packet (lookup). Tables are constructed by a separate routing daemon (OSPF, outing daemon (OSPF, BGP, or RIP).BGP, or RIP).

5.5. Finally packet will be sent to appropriate device driver for delFinally packet will be sent to appropriate device driver for delivery. Device driver will ivery. Device driver will perform fragmentation if needed before actually delivering the pperform fragmentation if needed before actually delivering the packet to NIC.acket to NIC.

Things that define performance:Things that define performance: Interrupt latencyInterrupt latency Bus bandwidthBus bandwidth Speed of the CPUSpeed of the CPU Memory bandwidthMemory bandwidth

Click RouterClick Router

Linux kernel implementation based on peer-to-peer packet transfer between processing blocks.

The router is assembled from packet processing modules called elements. Configuration consist of selecting elements and connecting them into a directed graph. (e.g. IP router has sixteen elements on its forwarding path)

Supports both push and pull (queue element as a connection between opposite ports)

Maximum loss-free forwarding rate for IP routing is 357,000 64-byte packets per second (4 year old number)

Fast PathFast Path

Software based Software based ““switchingswitching”” is amendable to changes but slowis amendable to changes but slow Hardware based Hardware based ““switchingswitching”” has very high processing rate but is has very high processing rate but is

inflexibleinflexible The switching architecture is optimized for functions needed forThe switching architecture is optimized for functions needed for

majority of packets majority of packets –– FAST PATH. FAST PATH. For For unicastunicast IPIP:: Packet parsing and validationPacket parsing and validation Routing table lookupRouting table lookup ARP mappingARP mapping Update TTL and header checksumUpdate TTL and header checksum

The rest of the features are implemented in softwareThe rest of the features are implemented in software Rarely used protocol optionsRarely used protocol options Fragmentation (if ports are not the same)Fragmentation (if ports are not the same) HousekeepingHousekeeping SNMP, ICMP, Exception conditionsSNMP, ICMP, Exception conditions

Cisco 6513 SwitchCisco 6513 Switch

The 13The 13--slot chassis based switchslot chassis based switch Variety of modules:Variety of modules:

Supervisor engines Supervisor engines Ethernet modules (Fast Ethernet, Gigabit Ethernet, 10 Gigabit EtEthernet modules (Fast Ethernet, Gigabit Ethernet, 10 Gigabit Ethernet)hernet) Flex WAN modules Flex WAN modules Shared Port Adaptors/SPA Interface Processors Shared Port Adaptors/SPA Interface Processors MultiMulti--Gigabit services modules (content services ,firewall, intrusion Gigabit services modules (content services ,firewall, intrusion detection, IP detection, IP

Security [IPSec], VPN, network analysis, and Secure Sockets LayeSecurity [IPSec], VPN, network analysis, and Secure Sockets Layer [SSL] r [SSL] acceleration) acceleration)

11521152Fast Fast

202010 Gig10 Gig577577GigGig

Max Density (ports)Max Density (ports)EthernetEthernet

1,000,0001,000,000Routes supportedRoutes supported

407Packets per second [Mpps]

64KMAC addresses supported

40Bandwidth per slot [Gbps]

720Total bandwidth [Gbps]

Performance (SUP720)

Virtual LANsVirtual LANs

Allows separation of Allows separation of logicallogical and and physicalphysical connectivityconnectivity multiple logical connections are sharing single physical multiple logical connections are sharing single physical

connectionconnection

VLAN 1

VLAN 2

VLAN 3

VLAN ConceptsVLAN Concepts Tagging Tagging

ImplicitImplicit explicitexplicit

AwarenessAwareness Association rulesAssociation rules Frame distributionFrame distribution

Virtual LANs (contd.)Virtual LANs (contd.)

Groupware environmentGroupware environmentFineFine--grained BW preservationgrained BW preservation

ApplicationApplicationProtocol based access controlProtocol based access controlProtocolProtocolIP mobilityIP mobilityIP subnetIP subnetStation mobilityStation mobilityMAC addressMAC address

Software patch panelSoftware patch panelSwitch segmentationSwitch segmentationSecurity and BW preservationSecurity and BW preservation

PortPortApplicationApplicationAssociation RuleAssociation Rule

802.1Q Tagging802.1Q Tagging

Priority Priority –– 802.1p guys needed 802.1p guys needed ““homehome”” Canonical Format Indicator (CFI) Canonical Format Indicator (CFI) –– indicates indicates endianesendianes of the of the

frameframe 0 0 --> addresses are in canonical format (Little > addresses are in canonical format (Little EndianEndian) and no source ) and no source

routing information in the VLAN tagrouting information in the VLAN tag 1 1 --> addresses are in non> addresses are in non--canonical format (Big canonical format (Big EnianEnian) and tag is ) and tag is

extended with source routing informationextended with source routing information VLAN Identifier VLAN Identifier –– up to 4096 up to 4096 VLANsVLANs

0xFFF 0xFFF -- RFURFU 0x000 0x000 –– used to indicate priority without VLANused to indicate priority without VLAN

DestinationAddress

SourceAddress

VLANProtocol

ID

TagControl

InfoData FCS

6 6 2 2 0-1500 4

Length/Type

2

0x8100 Priority

CF

I=0

Bytes

Bits 16 3 1

VLAN Identifier

12

802.1Q Switch Flow802.1Q Switch Flow

Port 1(input)

Port 2(input)

Port n(input)

.

.

.

AcceptableFrame Filter

IngressRules

IngressFilter

Forward.Decision


IngressRules

IngressFilter


IngressRules

IngressFilter

Forward.Decision

Forward.Decision

.

.

.

.

.

.

Port 1(outp.)

Port 2(outp.)

Port n(outp.)

.

.

.

EgressRules

EgressFilter

EgressRules

EgressFilter

EgressRules

EgressFilter

.

.

.

SwitchingFabric

Filtering DBIngress Progress Egress

Link Aggregation (802.3ad)Link Aggregation (802.3ad)

Frame Distributor

112

2

1213

Interface 1

Interface 2

Interface 3

Interface 4

Frame Collector

1

1

2

2

1

2

13

Interface 4

Interface 3

Interface 2

Interface 1

12 1

121

32

Switch 1 Switch 2

Timeline

AggregatorTransmitQueue

AggregatorReceiverQueue

Aggregated Links

REQUIREMENTS:•Mulitple interfaces with same MAC and data rate•Mapping (distribution function to physical links)•Configuration control (Link Aggregation Sublayer)

Unify multiple connections in a single link:Increased capacityIncremental capacityHigher availability

802.3ad802.3ad

Applies only to EthernetApplies only to Ethernet Burden is on Burden is on DistributorDistributor rather than rather than CollectorCollector Link Aggregation Control Protocol (LACP)Link Aggregation Control Protocol (LACP)

Concept of Concept of ActorActor and and PartnerPartner Port modes:Port modes:

Active mode Active mode –– port emits messages on a periodic basis port emits messages on a periodic basis (fast rate = 1 sec, slow rate (fast rate = 1 sec, slow rate –– 30 sec)30 sec)

Passive mode Passive mode –– port will not speak unless spoken toport will not speak unless spoken to

Network Management and Network Management and MonitoringMonitoring

SSimple imple NNetwork etwork MManagement anagement PProtocolrotocol

SNMP SNMP –– introduced in 1988 as a protocol for introduced in 1988 as a protocol for management of IP devicesmanagement of IP devices RFC 1157 RFC 1157 -- Simple Network Management Protocol Simple Network Management Protocol

(SNMP) (SNMP) RFC 1213 RFC 1213 -- The Management Information Base II The Management Information Base II

(MIB II)(MIB II) RFC 1902 RFC 1902 -- The Structure for Management The Structure for Management

Information (SMI)Information (SMI) A simple set of operations and information that A simple set of operations and information that

enables operator to set/get state of a deviceenables operator to set/get state of a device

SNMP (contd.)SNMP (contd.)

Managers and agentsManagers and agents UDP based protocolUDP based protocol Ports 161 and 162Ports 161 and 162 CommunityCommunity SMI SMI -- Managed Object Managed Object

with attributes:with attributes: NameName Type and syntaxType and syntax EncodingEncoding

NMS Application

UDPIP

Network Access

Agent Application

UDPIP

Network Access

Request

ResponseTrap

<name> OBJECT<name> OBJECT--TYPETYPESYNTAX <SYNTAX <datatypedatatype>>ACCESS <either readACCESS <either read--only, readonly, read--write, writewrite, write--only, or notonly, or not--accessible>accessible>STATUS <either mandatory, optional or obsolete>STATUS <either mandatory, optional or obsolete>DESCRIPTIONDESCRIPTION

““Textual description of the managed objectTextual description of the managed object””::=::={ <Unique OID that defines this object> }{ <Unique OID that defines this object> }

Management Information BaseManagement Information BaseLogical grouping of managed objects as they pertain to a Logical grouping of managed objects as they pertain to a

management taskmanagement task

Example Example MIBsMIBs MIBMIB--II (RFC 1213)II (RFC 1213) ATM (RFC 2515)ATM (RFC 2515) DNS Server (RFC 1611)DNS Server (RFC 1611) 802.11MIB802.11MIB CHRMCHRM--SYS.mibSYS.mib

(private Cisco (private Cisco mibmib for for forfor general system general system variables )variables )

root

ccitt0

Iso1

joint2

org3

dod6

internet1

directory1

management2

experimental3

private4

mib-22

enterprise1

Example:MIB managed object: 1.3.6.1.2.1.1.6 (iso.org.dod.internet.management.mib-2.system.sysLocation)

SNMP OperationsSNMP Operations

Simple request/response protocol. Simple request/response protocol. SNMP Operations:SNMP Operations:

Retrieving Data:Retrieving Data: get, get, getnextgetnext, , getbulkgetbulk, , getresponsegetresponse Altering VariablesAltering Variables : set: set Receiving Unsolicited Messages:Receiving Unsolicited Messages: trap, trap, notification, notification,

inform, reportinform, report Each operation has a standard Protocol Data Unit Each operation has a standard Protocol Data Unit

(PDU) format(PDU) format Most implementations have command line operation Most implementations have command line operation

equivalentsequivalents

SNMPv2 and SNMPv3 only

Management/Monitoring ToolsManagement/Monitoring ToolsCommercial SNMP basedCommercial SNMP based

NMSNMS HPHP’’ss OpenViewOpenView

Network Node Network Node ManagerManager

Castle RockCastle Rock’’s s SNMPcSNMPcEnterprise EditionEnterprise Edition

AgentAgent HP HP OpenViewOpenView AgentAgent OS SNMP AgentOS SNMP Agent Cisco IOSCisco IOS SystemEDGESystemEDGE

Open Source SNMP basedOpen Source SNMP based NMSNMS

NagiosNagios Multi Router Traffic Multi Router Traffic

GrapherGrapher (MRTG)(MRTG) OpenNMSOpenNMS NetdiscoNetdisco

AgentAgent NetNet--SNMPSNMP

Other toolsOther tools RRDToolRRDTool GangliaGanglia

Case Study:Case Study:ORBIT NetworkORBIT Network

ROUTING

Subnet IP Range Netmask Default Gateway

VLAN Note

Internal 10.0.0.0 255.255.0.0 10.0.0.1 2 CM 10.1.0.0 255.255.0.0 10.1.0.1 3 Aruba 10.2.0.0 255.255.0.0 10.2.0.1 4 Instrumentation 10.3.0.0 255.255.0.0 10.3.0.1 5 Control 10.10.0.0 255.255.0.0 10.10.0.1 6 Data 10.15.0.0 255.255.0.0 10.15.0.1 7 Winlab 10.20.0.0 255.255.0.0 10.20.0.1 8 Winlab network mapping

GRID VLANS VLAN

ID Usage

10 Frisbee 11 EDB1 to IDB1 copy 12 13

““BigBig”” PicturePicture

Network ProgrammingNetwork Programming

Linux KernelLinux Kernel

Hardware

a11

a22

3a3

4a4

b1

b2

b3

b4

5

6

7

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Vcc1

0 0

Vcc2

a11

a22

3a3

4a4

b1

b2

b3

b4

5

6

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8GND

0

Process Management

ArchitectureDependant

Code

a11

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b1b2b3b4

5678Vcc1

0 0

Vcc2a1

1a2

23a34a4

b1b2b3b4

5678GND

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5678Vcc1

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Vcc2a1

1a2

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5678GND

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1a2

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1a2

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5678GND

0

MemoryManager

File System Types

Character Devices

NetworkSubsystem

Block devices NetworkDrivers

CPU Memory Disk Console NIC

MemoryManagement Filesystems Device

Control Networking

ConcurrencyMultitasking

VirtualMemory Files and drs TTYS Connectivity

KernelSubsystem

FeatureImplemented

SoftwareSupport

The System Call Interface

Linux Protocol Stack LayeringLinux Protocol Stack Layering

BSD sockets layer – provides standard UNIX sockets API for inter-process communication (not necessarily only across network).

INET layer – manages communication end-points for the IP based protocols (TCP and UDP).

Device driver – manages physical device.

Application routed

(BSD) Socket Interface

INET Socket Interface

TCP UDP

IP

Device Driver

Socket Address StructuresSocket Address Structures

Generic socket address structureGeneric socket address structure

Always passed by referenceAlways passed by reference Socket functions take pointer to Socket functions take pointer to

the generic socket address the generic socket address structurestructure

Protocol dependant address Protocol dependant address conversion functionsconversion functions

Linux Linux sockaddrssockaddrs don't have a don't have a length field, only a familylength field, only a family

Length AF_INET

16 bit port#

32-bitIPv4 address

Unused

sockaddr_in()IPv4

Length AF_INET6

16 bit port#

32-bitFlow label

sockaddr_in6()IPv6

16 bytes128-bit

IPv6 address

Length AF_LOCAL

sockaddr_un()Unix

Pathname(up to 1024 bytes)

24 bytes

variable

Length AF_LINK

Interface index

sockaddr_dl()Datalink

Interface nameand

link-layer address

variable

Type Name len.Addr. Len. Sel. len

struct sockaddr{uint8_t sa_len;sa_family_t sa_family;char sa_data[14];

}

struct sockaddr_in server; // IPv4…bind(sockfd, (struct sockaddr *) server, sizeof(server));

#define AF_UNSPEC 0#define AF_UNIX 1 /* Unix domain sockets */#define AF_LOCAL 1 /* POSIX name for AF_UNIX */#define AF_INET 2 /* Internet IP Protocol */#define AF_AX25 3 /* Amateur Radio AX.25 */#define AF_IPX 4 /* Novell IPX */#define AF_APPLETALK 5 /* AppleTalk DDP */#define AF_NETROM 6 /* Amateur Radio NET/ROM */#define AF_BRIDGE 7 /* Multiprotocol bridge */#define AF_ATMPVC 8 /* ATM PVCs */#define AF_X25 9 /* Reserved for X.25 project */#define AF_INET6 10 /* IP version 6 */

Support FunctionsSupport Functions

Byte Ordering FunctionsByte Ordering Functions EndiannessEndianness -- order in which integer values are stored order in which integer values are stored

as bytes in computer memory (byte order)as bytes in computer memory (byte order)

Internet protocol use bigInternet protocol use big--endian byte ordering for endian byte ordering for multibytemultibyte integers (integers (network byte ordernetwork byte order))

““ll”” –– long (32 bit), long (32 bit), ““ss”” –– short (16short (16--bit)bit) On systems with same host and network byte order On systems with same host and network byte order

these are null macrosthese are null macros

Byte Manipulating FunctionsByte Manipulating Functions

Address Conversion FunctionsAddress Conversion Functions Convert between ASCII string and network Convert between ASCII string and network

byte ordered binary valuesbyte ordered binary values

#include <strings.h>

void bzero(void *s, size_t n);void bcopy(const void *src, void *dest, size_t n);int bcmp(const void *s1, const void *s2, size_t n);

#include <netinet/in.h>#include <arpa/inet.h>

int inet_aton(const char *cp, struct in_addr *inp);char *inet_ntoa(struct in_addr in);in_addr_t inet_addr(const char *cp);

int inet_pton(int af, const char *src, void *dst);const char *inet_ntop(int af, const void *src, char *dst,

socklen_t cnt);

#include <netinet/in.h>#include <arpa/inet.h>

uint32_t htonl(uint32_t hostlong);uint16_t htons(uint16_t hostshort);uint32_t ntohl(uint32_t netlong);uint16_t ntohs(uint16_t netshort);

Big Big endianendianLittle Little endianendian

LowLow--bytebyteHighHigh--bytebyteaddraddr A+1A+1

HighHigh--bytebyteLowLow--bytebyteaddraddr AA

Socket FunctionsSocket Functions

Creates an endpoint for communication and returns a (socket) Creates an endpoint for communication and returns a (socket) descriptor.descriptor.

Functions Functions setsockoptsetsockopt and and getsockoptgetsockopt can be used to control the socket can be used to control the socket operation.operation.

Raw network protocol accessRaw network protocol accessSOCK_RAWSOCK_RAW

Reliable datagram layer that does not guarantee orderingReliable datagram layer that does not guarantee orderingSOCK_RDMSOCK_RDM

Sequenced, reliable, twoSequenced, reliable, two--way connectionway connection--based datagram based datagram layerlayer

SOCK_SEQPACKETSOCK_SEQPACKET

OboleteOboleteSOCK_PACKETSOCK_PACKET

Connectionless, unreliable fixed maximum Connectionless, unreliable fixed maximum length length datagramsdatagrams (UDP)(UDP)

SOCK_DGRAMSOCK_DGRAM

Sequenced, reliable, twoSequenced, reliable, two--way, connectionway, connection--based based byte streams (TCP)byte streams (TCP)

SOCK_STREAMSOCK_STREAM

DescriptionDescriptionTypeType

#include <sys/types.h>#include <sys/socket.h>

int socket(int domain, int type, int protocol);

IPv6 Internet protocolsIPv6 Internet protocolsPF_INET6PF_INET6

IPX IPX -- Novell protocolsNovell protocolsPF_IPXPF_IPX

Bluetooth socketsBluetooth socketsPF_BLUETOOTHPF_BLUETOOTH

Low level packet interfaceLow level packet interfacePF_PACKETPF_PACKET

AppletalkAppletalkPF_APPLETALKPF_APPLETALK

Access to raw ATM Access to raw ATM PVCsPVCsPF_ATMPVCPF_ATMPVC

Amateur radio AX.25 protocolAmateur radio AX.25 protocolPF_AX25PF_AX25

ITUITU--T X.25 / ISOT X.25 / ISO--8208 protocol8208 protocolPF_X25PF_X25

IPv4 Internet protocolsIPv4 Internet protocolsPF_INETPF_INET

Local communicationLocal communicationPF_UNIX,PF_LOCALPF_UNIX,PF_LOCAL

ProtocolProtocolFamily (domain)Family (domain)

Socket Functions (contd.)Socket Functions (contd.)

Connects the Connects the sockfdsockfd socket to the address specified by socket to the address specified by serv_addrserv_addr Clients: kernel will chose source address and ephemeral port Clients: kernel will chose source address and ephemeral port For connectionFor connection--based protocol it will attempt to connect; for based protocol it will attempt to connect; for

connectionless sets the default destination address.connectionless sets the default destination address. Return 0 on success; Return 0 on success; --1 and 1 and errnoerrno on failure.on failure.


int connect(int sockfd, const struct sockaddr *serv_addr, socklen_t addrlen);


int bind(int sockfd, const struct sockaddr *my_addr, socklen_t addrlen);

Assigns local address to the Assigns local address to the sockfdsockfd socket (also socket (also refferedreffered to as to as ““passigningpassigning a name to a socketa name to a socket””)) Used by servers to Used by servers to ““bind their well known portbind their well known port””; on clients, can be used to a ; on clients, can be used to a

specific IP address for multispecific IP address for multi--homed hosts.homed hosts. Return 0 on success; Return 0 on success; --1 and 1 and errnoerrno on failure.on failure.


Extracts the first from the queue of pending connections, createExtracts the first from the queue of pending connections, creates a s a new connected socket, and returns a new file descriptor referrinnew connected socket, and returns a new file descriptor referring to g to that socket.that socket. Only for connectionOnly for connection--based protocols; blocks until connection is availablebased protocols; blocks until connection is available addraddr is filled in with the address of the peeris filled in with the address of the peer Returns Returns socketfdsocketfd on success; on success; --1 and 1 and errnoerrno on failure.on failure.


int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);


int listen(int sockfd, int backlog);

Indicated willingness to accept incoming connections Indicated willingness to accept incoming connections backlogbacklog –– maximum queue length for established sockets waiting to be maximum queue length for established sockets waiting to be

accepted (the ones for which threeaccepted (the ones for which three--way way handhsakehandhsake has completed)has completed) Return 0 on success; Return 0 on success; --1 and 1 and errnoerrno on failure.on failure.


Closes the socket descriptor.Closes the socket descriptor. Returns Returns socketfdsocketfd on success; on success; --1 and 1 and errnoerrno on failure.on failure.


int close(int fd);


ssize_t recv(int s, void *buf, size_t len, int flags);ssize_t recvfrom(int s, void *buf, size_t len, int flags, struct sockaddr *from, socklen_t *fromlen);

ssize_t send(int s, const void *buf, size_t len, int flags);ssize_t sendto(int s, const void *buf, size_t len, int flags, const struct sockaddr *to, socklen_t tolen);

Used to receive and send data Used to receive and send data If no data, the receive call waits (unless If no data, the receive call waits (unless nonblockingnonblocking); otherwise it returns any data ); otherwise it returns any data

available, up to available, up to lenlen.. For send, socket has to be in connected state (endpoint has to bFor send, socket has to be in connected state (endpoint has to be set); error is also e set); error is also

returned for message too long to pass atomically through the undreturned for message too long to pass atomically through the underlying protocol.erlying protocol. All functions return the length of the data on success; All functions return the length of the data on success; --1 and 1 and errnoerrno on failure.on failure.

Simple TCP ClientSimple TCP Client--Server ExampleServer Example

socket()

bind()

listen()

accept()

socket()

TCP Server

TCP Client

connect()

write()

read()

read()write()

close()close()

Data (request)

Data (reply)

End-of-file notification

Conection establishment

(TCP three-way handshake

ECHO Server: ECHO Server: Client sends a line of textClient sends a line of text Server reads that line end Server reads that line end

echoes it backechoes it back Client reads the line and Client reads the line and

displays it on its displays it on its stdoutstdout

ClientClient

/*/** Simple echo client* Simple echo client*/*/

#include <#include <stdio.hstdio.h>>#include <#include <stdlib.hstdlib.h>>#include <#include <strings.hstrings.h>>#include <#include <errno.herrno.h>>#include <#include <resolv.hresolv.h>>#include <sys/#include <sys/socket.hsocket.h>>#include <#include <arpa/inet.harpa/inet.h>>

#define SERVER "127.0.0.1"#define SERVER "127.0.0.1"#define ECHO_PORT 7+1000#define ECHO_PORT 7+1000#define MAXBUF 1024#define MAXBUF 1024

intint main()main(){{

intint sockfdsockfd;;structstruct sockaddr_insockaddr_in servaddrservaddr;;char char buffer[MAXBUFbuffer[MAXBUF];];

if ( (if ( (sockfdsockfd = = socket(socket(AF_INETAF_INET, SOCK_STREAM, 0)) < 0 ), SOCK_STREAM, 0)) < 0 ){{perror("socketperror("socket"); "); exit(errnoexit(errno););

}}

/* Server address structure *//* Server address structure */bzero(&servaddrbzero(&servaddr, , sizeof(servaddrsizeof(servaddr));));servaddr.sin_familyservaddr.sin_family = AF_INET;= AF_INET;servaddr.sin_portservaddr.sin_port = = htons(ECHO_PORThtons(ECHO_PORT); // Port); // Portif ( if ( inet_atoninet_aton(SERVER(SERVER, &, &servaddr.sin_addrservaddr.sin_addr) == 0 ) // Address) == 0 ) // Address{{perror(SERVERperror(SERVER); ); exit(errnoexit(errno););

}}/* Connect to server *//* Connect to server */if ( if ( connectconnect(sockfd(sockfd, (, (structstruct sockaddrsockaddr*)&*)&servaddrservaddr, ,

sizeof(servaddrsizeof(servaddr)) != 0 ))) != 0 ){{perror("connectperror("connect"); "); exit(errnoexit(errno););

}}sprintf(buffer,"Testsprintf(buffer,"Test message");message");sendsend(sockfd(sockfd, buffer, , buffer, sizeof(buffersizeof(buffer), 0);), 0);bzero(bufferbzero(buffer, MAXBUF);, MAXBUF);recvrecv(sockfd(sockfd, buffer, , buffer, sizeof(buffersizeof(buffer), 0);), 0);printf("%sprintf("%s\\nn", buffer);", buffer);closeclose(sockfd(sockfd););return 0;return 0;

}}

ServerServerservaddr.sin_addr.s_addrservaddr.sin_addr.s_addr = INADDR_ANY; // On any interface= INADDR_ANY; // On any interfaceservaddr.sin_portservaddr.sin_port = = htons(ECHO_PORThtons(ECHO_PORT); // Our port); // Our port/* Let's bind to the port/address *//* Let's bind to the port/address */if ( if ( bind(sockfdbind(sockfd, (, (structstruct sockaddrsockaddr*)&*)&servaddrservaddr, , sizeof(servaddrsizeof(servaddr)) != 0 ))) != 0 ){{perror("bindperror("bind");");exit(errnoexit(errno););

}}

/* We are the server *//* We are the server */if ( if ( listen(sockfdlisten(sockfd, LISTENQ) != 0 ), LISTENQ) != 0 ){{perror("listenperror("listen");");exit(errnoexit(errno););

}}

for ( ; ; )for ( ; ; ){{intint clientfdclientfd;;structstruct sockaddr_insockaddr_in clientaddrclientaddr;;intint addrlenaddrlen==sizeof(clientaddrsizeof(clientaddr););

/* Accept a client connection *//* Accept a client connection */clientfdclientfd = = accept(sockfdaccept(sockfd, (, (structstruct sockaddrsockaddr*)&*)&clientaddrclientaddr, &, &addrlenaddrlen););printf("%s:%dprintf("%s:%d connectedconnected\\n", n", inet_ntoa(clientaddr.sin_addrinet_ntoa(clientaddr.sin_addr),),

ntohs(clientaddr.sin_portntohs(clientaddr.sin_port));));send(clientfdsend(clientfd, buffer, , buffer, recv(clientfdrecv(clientfd, buffer, MAXBUF, 0), 0);, buffer, MAXBUF, 0), 0);close(clientfdclose(clientfd););

}}close(sockfdclose(sockfd););return 0;return 0;

}}

/* Simple echo server. *//* Simple echo server. */#include <#include <stdio.hstdio.h>>#include <#include <stdlib.hstdlib.h>>#include <#include <strings.hstrings.h>>#include <#include <errno.herrno.h>>#include <#include <resolv.hresolv.h>>#include <sys/#include <sys/socket.hsocket.h>>#include <#include <arpa/inet.harpa/inet.h>>

#define ECHO_PORT 7 + 1000#define ECHO_PORT 7 + 1000#define MAXBUF 1024#define MAXBUF 1024#define LISTENQ 20#define LISTENQ 20

intint main(intmain(int argcargc, char *, char *argvargv[])[]){{intint sockfdsockfd;;structstruct sockaddr_insockaddr_in servaddrservaddr;;char char buffer[MAXBUFbuffer[MAXBUF];];

/*/** Create a TCP socket* Create a TCP socket*/*/if ( (if ( (sockfdsockfd = = socketsocket(AF_INET(AF_INET, SOCK_STREAM, 0)) < 0 ), SOCK_STREAM, 0)) < 0 ){{/* Show why we failed *//* Show why we failed */perror("socketperror("socket");");exit(errnoexit(errno););

}}/* Set our address and port *//* Set our address and port */bzero(&servaddrbzero(&servaddr, , sizeof(servaddrsizeof(servaddr));));servaddr.sin_familyservaddr.sin_family = AF_INET;= AF_INET;

L6: Network Hardware and Software ECE 544: Computer ...

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