N E T W O R K S T A N D A R D S UNIT 5. Ethernet LANs & P R O T O C O L S DPW

Transcription

1 UI 5 thernet s onna arren

2 opics for this Unit thernet History ypical network components functionality versus technologies and specifications he advantages and disadvantages of thernet technology in s dvantages of using ayer 2 devices to segment s ools to roubleshoot wired s onna arren

3 Introduction to thernet onna arren

4 etwork rchitectures thernet oken ing FI (Fiber istributed ata Interface) ireless onna arren

5 hared ccess etworks hared ccess etworks assume multiple nodes on the same physical link Bus, ring and wireless structures ransmission sent by one node is received by all others o intermediate switches eed methods for moderating access (M protocols) Fairness erformance onna arren

6 Multiple ccess Methods Fixed assignment artition the channel so each node gets a slice of the bandwidth ssentially circuit switching thus inefficient xamples: M, FM, M (all used in wireless/cellular environments) ontention-based odes contends equally for bandwidth and recover from collisions such as thernet oken-based or reservation-based ake turns using the channel such as token ring onna arren

7 History thernet eveloped by Bob Metcalfe and others at Xerox in mid-1970s tandardized by Xerox,, and Intel in 1978 standards define M and physical layer connectivity I (M/ - thernet) I 802.3u- 100Mbps I 802.3z - 1,000Mbps onna arren

8 thernet tandard hysical ayer standard defines both M and physical layer details he picture below is Metcalfe s original sketch. onna arren

9 ireless thernet onna arren

10 Informal thernet ames peed Informal ame 10 Mbps thernet 100 Mbps Fast thernet Fast ther common informal names 1 Gbps Gigabit thernet Gig, 1 Gb 10 Gbps 10 Gig 10 Gb 40 Gbps 40 Gig 40 Gb 100 Gbps 100 Gig 100 Gb onna arren

11 M/ M/ - thernet s Media ccess ontrol (M) = carrier sense M = multiple access = collision detection end only if medium is idle top sending immediately if collision is detected onna arren

12 ollision omains onna arren

13 ypical thernet onna arren

14 tate iagram for M/ acket? ense arrier end o etect ollision iscard acket attempts < 16 attempts == 16 Yes Jam channel b=alcbackoff(); wait(b); attempts++; onna arren

15 ollision etection/backoff rocess onna arren

16 M lgorithm enders handle all access control eceivers simply read frames with acceptable address ddress to host ddress to broadcast ddress to multicast to which host belongs ll frames if host is in promiscuous mode onna arren

17 thernet and the I Model onna arren

18 ayered ata ncapsulation onna arren

19 thernet and the I Model onna arren

20 M aming onna arren

21 Frame ata ncapsulation ach layer of the I model can add a header and/or trailer to the message onna arren

22 ayer 2 Framing onna arren

23 thernet Frame tructure onna arren

24 thernet rrors ollision or runt - imultaneous transmission occurring before slot time has elapsed ate collision - imultaneous transmission occurring after slot time has elapsed Jabber, long frame and range errors - transmission >1504 bytes hort frame, collision fragment or runt - transmission < 64 bytes F / error - orrupted transmission lignment error - Insufficient or excessive number of bits transmitted ange error - ctual and reported number of octets in frame do not match (length field) Ghost or jabber - Unusually long reamble or Jam event onna arren

25 uplex ort onfiguration uplex must be the same on both ends of the cable Full / half mismatch won t work Full / auto negotiate auto side defaults to half - mismatch Half / auto negotiate auto defaults to half works uto negotiate / auto negotiate depends on cables (eg. GB defaults to full and 100Mbps defaults to half) onna arren

26 peed ort onfiguration ifferent speeds mismatch peed / auto will revert to lowest speed mismatch if different uto / auto each reverts to lowest speed mismatch if different onna arren

27 ypes of witching ymmetric applies the same amount of bandwidth to each active port symmetric can provide variable amounts of bandwidth to each port to do better load balancing ort based memory buffers - use memory tied to port (slower) hares memory buffers only requires a single queue so faster onna arren

28 witched thernet he advantage the backplane is able to repeat more than one frame in parallel because there is a separate backplane bus line for each node he frame is relayed onto the required output port via the port s own backplane bus line hile collisions are still possible when two concurrently arriving frames are destined for the same station, the probability is approaching zero ach parallel transmission can take place at the switch s maximum speed onna arren

29 witching onna arren

30 witch Broadcast onna arren

31 /I roubleshooting ools onna arren

32 Internet ontrol Message rotocol IM (Internet ontrol Message rotocol) - reports messages and errors regarding data delivery (eg. Used by ping) estination Unreachable (ime to ive) ource Quench - input buffers full edirect cho and cho eply onna arren

33 arp arp (ddress resolution protocol) - displays I address mapped to M addresses :\> arp -a Interface: on Interface 2 Internet ddress hysical ddress ype e0-f ca dynamic Interface - the I address the machine where arp -a was executed Interface 2 indicates that this is only one of the interfaces on this computer onna arren

34 ipconfig ipconfig - display s the computer s I configuration :\> ipconfig /all thernet adapter 100B1: escription : Intel therxpress /100B I dapter hysical ddress..... : B0-57-4B-8 H nabled : Yes I ddress : ubnet Mask : efault Gateway.... : H erver : rimary I erver.. : econdary I erver. : ease btained.: hursday, January 14, :48:50 M ease xpires.: Friday, January 15, :48:50 M onna arren

35 ping ping (acket Internet Gopher) - used to test connectivity :\> ping inging with 32 bytes of data: eply from : bytes=32time<10ms =255 eply from : bytes=32time<10ms =255 eply from : bytes=32time<10ms =255 eply from : bytes=32time<10ms =255 onna arren

36 netstat netstat - isplays protocol statistics and current /I network connections onna arren

37 tracert racert traces the route to a destination address onna arren

38 ab 5 esearching tandards omparing M and I ddresses ractice using the following /I tools rp ping ipconfig tracert netstat roubleshooting research onna arren