1. ECEN5553 Telecom Systems Week #4 Readings: Read [5a] "Whatever Happened to the IPv4 Address Crisis? thru [5c] "How Can the Internet Have Too Many Routes and Not Enough Addresses" Read [6] "The Cognitive Net is Coming" Exam #1: Lecture 14, 16 September (Live) No later than 23 September (Remote DL) 4 page test. Work pages will be off Fall 2015 Exam #1 Outline: Lecture 22, 5 October (Live) No later than 12 October (Remote DL)

2. Outlines Received due 5 October (local) 12 October (remote)
5 %

3. IEEE Ethernet
Mbps (1983)
Coax → Twisted Pair
Shared → Switched
Half Duplex → Full Duplex
802.3u 100 Mbps Fast Ethernet (1995)
802.3z 1 Gbps Ethernet (1998)
802.3ae 10 Gbps Ethernet (2002)
802.3ba 40 & 100 Gbps Ethernet (2010)
802.3bs 400 Gbps Ethernet (2017?)

4. Performance Issues Throughput Efficiency Shared Ethernet Efficiency
Usable BW
Efficiency
Percent of time packets are moved
Shared Ethernet Efficiency
100% under Low Load
≈ 1/(1+5*NPD) under Heavy Load

5. Low Speed Network? This configuration...PC
Server
Hub PC PC
10BaseT & Shared Hub

6. ... is as good as this one... 10BaseT & Switched HubPC
Server
Switched
Hub PC PC
10BaseT & Switched Hub
...IF traffic mostly going to/from same machine
Switched Hub better if diverse traffic flow

7. This configuration is even better.PC
Server
1 Gbps
10 Mbps
Switch
100 Mbps
10 Mbps PC PC
Server on a higher speed line.

8. Shared Ethernet Efficiency Gbps has higher NPD
1.0
0.5
0.0
NPD .1 1 10

9. High Speed Network? This configuration has horrible throughput.PC
Server
Shared
Hub PC PC
1 or 10 Gbps & Shared Hub
Under heavy load, too much time
spent recovering from collisions.

10. Ethernet (Shared) Hub Operates at OSI Level 1
‘Electric Cable’ Traffic arriving at an input is immediately copied to all other ports on a bit-by bit basis.
Used on LAN's. Pretty much obsolete.
Repeater = single input & single output hub
Not used much on Ethernet any more
Generally now only used on WAN long haul
May be different protocol than Ethernet

11. Black Box Performance...
From
Node A To
Node A
OSI Level 1
LAN Hub
Node B
Node B
Node C
Node C
Two packets simultaneously show up at input...

12. Black Box Performance...
From
Node A To
Node A
OSI Level 1
LAN Hub
Node B
Node B
Node C
Node C
... will overwrite each other, i.e. garbage out.
a.k.a. Shared Hub

13. Black Box Performance...
OSI Level
1-2 (Switch)
or 1-3 (Router)

14. Black Box Performance... Two packets simultaneously show up at input
OSI Level
1-2 (Switch)
or 1-3 (Router)
Two packets simultaneously show up at input
& need to exit on same output...

15. Black Box Performance...
OSI Level
1-2 (Switch)
or 1-3 (Router)
... one will be transmitted (when allowed by MAC),
the other momentarily buffered...

16. Black Box Performance... ... and then transmitted. OSI Level
1-2 (Switch)
or 1-3 (Router)
... and then transmitted.

17. One big collision domain.
10BaseT & Shared Hub PC
53 m PC
8 m
Hub PC PC
26 m
17 m
One big collision domain.

18. 10BaseT & Half Duplex SwitchPC
53 m PC
8 m
Switch PC PC
26 m
17 m
Four smaller collision domains.

19. Right Side to World gets
Example
If Box 1 & 2 are Level 1 Hubs
One Big Collision Domain
15 Nodes share 10 Mbps
Each node gets average of 10/15 Mbps
World
10BaseT 7
Users 7
Users
Hub 2
Hub 1
Right Side to World gets
7/15th of available BW,
on average.

20. Example If Box 1 & 2 are Level 2 Switches
Each node shares 10 Mbps with Switch
Right Hand Side is on one 10 Mbps line.
World
10BaseT 7
Users 7
Users
Sw 2
Sw 1
Right Side to World gets
_____ of available BW.
1/8th
(Was 7/15th)
Right hand side sees
increased delays.
Can be alleviated with
100 Mbps Box 1 ↔ Box 2 link.

21. Switched Hubs or Bridge
On Power Up know nothing
When a packet arrives at an input port...
Look-Up Table consulted
Source MAC address not in table?
Table Updated: MAC address & Port matched
Destination MAC address not in table?
Packet broadcast to all outputs (a.k.a. flooding)
Destination MAC address in table?
Packet shipped to proper output
Look-up Table update is dependent on packet arrivals

22. Router Operates at OSI Layers 1, 2, & 3
Capable of making complex routing decisions
‘peers into’ packets and examines Layer 3 address
Very useful on Large Networks with multiple end-to-end paths
Routers frequently exchange connectivity info with neighboring Routers
Routing Algorithms used to update Routing (Look-Up) Tables
Tables updated independently of traffic

23. Bridging versus Routing
Ethernet Bridge, Switch, or Switched Hub
Uses Layer 2 MAC Address
Unknown Destination? Flooded
Look-up Table updates are packet dependent
Router
Uses Layer 3 Internet Protocol Address
Unknown Destination? Default location
Look-up Tables updated independently of traffic
Small Network? Doesn't matter
Big Network? Floods not a good idea.

24. Ethernet Switch Uses MAC Source Address to populate Look-Up Table
Uses MAC Destination Address & Table for I/O Decision
Bytes:
Pre
SFD
Destination
Address
Source
Len
CRC
Data + Padding

25. Router Populates Look-Up table independently of traffic.
Uses Destination IP Address & Table for I/O Decision
Bytes:
MAC
Destination
Address
MAC
Source
Address
Does look at the MAC Address! Is this for me?
IPv4
TCP
Data + Padding
CRC

26. Data Network Addressing
IP Address
Global Information Source
Global Information Sink
Stays unchanged end-to-end
Exception: Network Address Translation
Ethernet Address
Local Transmitter (MAC Source)
Local Receiver (MAC Receiver)
Crossing a Router (Ethernet Boundary)?
MAC Header and Trailer swapped out
Crossing a Switch?
MAC Header and Trailer unchanged

27. Multiplexing
Sharing a chunk of Bandwidth by splitting it into channels
Channel can carry one conversation
FDM, TDM, & StatMux

28. FDM 1 2 3 4 5 time Different channels use some of
the frequency all of the time.
frequency 1 2 3 4 5
time

29. TDM 1 2 3 time 1 etc. Different channels use all of
the frequency some of the time.
Fixed, predictable times.
TDM
frequency 1 2 3
time 1
etc.

30. StatMux 1 3 1 time 2 Different channels use all of
the frequency some of the time,
at random, as needed.
frequency 1 3 1
time 2

31. StatMux vs. TDM & FDM
uses bandwidth more efficiently for bursty traffic
requires more overhead
has more variable deliveries
requires more complex hardware

32. Switching: In what manner will a user get to use a channel?
For the duration of the conversation? Circuit Switching
For a tiny, variable length, portion of the conversation? Packet Switching
Circuit vs. Packet Switching Circuit has less end-to-end delay Circuit is less complex Packet is more efficient for Bursty Traffic

33. X X StatMux TDM FDM Circuit Packet MULTIPLEXING SWITCHING
Any Switching & Multiplexing combo possible.
Two marked are among most common today.

34. LAN/MAN History: FDDI (Fiber Distributed Data Interface)
Developed in ’87 – ‘88
Covered OSI Layers 1 & 2
1st 100 Mbps Line Speed
Token Ring MAC
Guaranteed Bandwidth
Had Priorities.
Originally Dual Counter-Rotating Rings

35. Designed for Metropolitan Area Counter Rotating Fiber Rings
Outside Active.
Inside Hot Standby.

36. Designed for Metropolitan Area Counter Rotating Fiber Rings1
Line
Break...
Nodes 1 & 4 wrap.
One big ring. 4

37. FDDI Status Never succeeded as a LAN
NIC's too expensive
Saw use mostly as a corporate backbone
OSU backbone from ish
Was fairly common at Internet Exchanges
Used to pass traffic from ISP A to ISP B
Now too slow
RIP

38. 1993 OSU Stillwater Network
(15)
(21)
1993 OSU Stillwater Network

39. The Internet VAST collection of interconnected networks
Key Building Block: Routers running IP (Layer 3)
Router link speeds range up to 200 Gbps
Hierarchical Alpha-Numeric Names

40. AT&T 1997 Internet Backbone

41. UUNET 1998 Internet Backbone

42. AT&T 2009 Internet Backbone
Source:

43. Washington D.C. Area

44. OSU 2009 Internet Connectivity

45. Traceroute to WWW.CISCO.COM
3 Internal OSU-Stillwater routers
4 OneNet routers (all in OKC? Tulsa?)
3 Qwest routers dal-edge-18.inet.qwest.net
Akamai Technologies (Hosting Service)
(11:51 am, 9Sept15, rtt = 13 msec, 10 routers) (12:32 pm, 9Sept16, rtt = 13 msec, 10 routers)

46. Traceroute to WWW.TULSA.COM
3 Internal OSU-Stillwater routers
3 OneNet routers (Tulsa)
5 Cogent Communications routers
te rcr21.tul01.atlas.cogentco.com
be2706.ccr21.mci01.atlas.cogentco.com (Kansas City?)
be3035.ccr21.den01.atlas.cogentco.com
be3037.ccr21.slc01.atlas.cogentco.com
4 Unified Layer routers (Hosting Service)
prv unifiedlayer.com
End server ( ) in Provo, Utah area?
(12:43 pm, 9Sept16, rtt = 45 msec, 15 routers)

47. ISP Routes Sometimes Roundabout
Launched 13 September 2014, 2 miles from OSU campus
1 Scheets' home router
4 AT&T routers
adsl dsl.okcyok.sbcglobal.net
ggr3.dlstx.ip.att.net
4 Cogent Communications routers
Be2032.ccr22.dfw01.atlat.cogentco.com
te rcr12.okc01.atlas.cogentco.com
3 ONENET routers
OKC?
3 Oklahoma State routers
(12:30 pm, 11Sept14, rtt = 84 msec, 15 routers)

48. Fall 2007 Weird TraceRoute Seen by Student Tulsa to OSU Stillwater
Tracert launched from Tulsa, hit Atlanta Washington, D.C. Illinois Kansas City Tulsa Oklahoma City OSU Stillwater

49. Internet Service Provider Backbone
Trunks
Access Line
Router
Switched Network, full duplex trunks.
Access lines attach to corporate routers &
routers of other ISP's.