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ECEN5553 Telecom Systems
Week #4
Readings:
[7] "Internet QoS: Pieces of the Puzzle"
[8a] "The End of IPv4 is Nearly Here- Really"
[8b] "What Happened to the IPv4 Address Crisis?"
Exam #1 Lecture 15, 21 September (Live)
No later than 28 September (Remote DL)
Outline 7 October 2015, Lecture 22 (Live)
No later than 14 October (Remote DL)
Outlines
Received
due 7 October (local)
14 October (remote)
6%
Multiplexing
Sharing a chunk of Bandwidth
by splitting it into channels
 Channel can carry one conversation


FDM, TDM, & StatMux
FDM
Different channels use some of
the frequency all of the time.
frequency
1
2
3
4
5
TDM
Different channels use all of
the frequency some of the time.
Fixed, predictable times.
frequency
1
2
3
1
StatMux
Different channels use all of
the frequency some of the time,
at random, as needed.
frequency
1
3
1
2
StatMux vs. TDM & FDM
uses bandwidth more efficiently for
bursty traffic
 requires more overhead
 has more variable deliveries
 requires more complex hardware

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

MULTIPLEXING
SWITCHING
StatMux
Circuit
Packet
TDM
FDM
X
X
Any Switching & Multiplexing combo possible.
Two marked are among most common today.
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

Designed for Metropolitan Area
Counter Rotating Fiber Rings
Outside Active.
Inside Hot Standby.
Designed for Metropolitan Area
Counter Rotating Fiber Rings
1
Line
Break...
Nodes 1 & 4 wrap.
One big ring.
4
FDDI Status
 Never
succeeded as a LAN
 NIC's
too expensive
 Dirt cheap now!
 Saw
use mostly as a corporate backbone
 OSU
 Was
backbone from 1989 - 1993 ish
fairly common at Internet Exchanges
 Used
to pass traffic
from ISP A to ISP B
 Now too slow
1993 OSU Stillwater Network
(15)
(21)
The Internet
VAST collection of interconnected
networks
 Key Building Block:
Routers running IP (Layer 3)
 Router link speeds range up to 100 Gbps
 Hierarchical Alpha-Numeric Names
[email protected]

AT&T 1997 Internet Backbone
UUNET 1998 Internet Backbone
AT&T 2009 Internet Backbone
Source: http://www.business.att.com/content/productbrochures/MIS_15906.pdf
Washington D.C. Area - 2000
OSU 2009 Internet Connectivity
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)
Traceroute to WWW.TULSA.COM



3 Internal OSU-Stillwater routers
4 OneNet routers (OKC? Tulsa?)
1 WiscNet router





r-equinix-isp-xe-1-0-0-2362.wiscnet.net
3 Ace Data Center routers (Hosting Service)
 tg1-2.br01.chcg.acedc.NET
 ve15.ar05.prov.acedc.net
3 Unified Layer routers (Hosting Service?)
End server (198.57.177.235) in Provo, Utah area?
(12:05 pm, 9Sept15, rtt = 53 msec, 14 routers)
ISP Routes Sometimes Roundabout
Launched 13 September 2014, 2 miles from OSU campus
 1 Scheets' home router
 4 AT&T routers
 adsl-70-233-159-254.dsl.okcyok.sbcglobal.net
 ggr3.dlstx.ip.att.net
 4 Cogent Communications routers
 Be2032.ccr22.dfw01.atlat.cogentco.com
 te0-0-2-1.rcr12.okc01.atlas.cogentco.com
 3 ONENET routers
 OKC?
 3 Oklahoma State routers
 (12:30 pm, 11Sept14, rtt = 84 msec, 15 routers)
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
Internet Service Provider Backbone
Router
Switched Network, full duplex trunks.
Access lines attach to corporate routers &
routers of other ISP's.
OSU Backbone
Router
Access lines attach to switches and other routers.
Highest internal trunk speeds currently 10 Gbps.
Moving to 40 & 100 Gbps between now & end of 2015.
ISO OSI Seven Layer Model
Layer 7
 Layer 6
 Layer 5
 Layer 4
 Layer 3
 Layer 2
 Layer 1

Application
Presentation
Session
Transport
Network
Data Link
Physical
Windows API
Windows TCP
Windows TCP
Windows IP
PC NIC
PC NIC
Internet Protocal v4 (20 Bytes)
4 Bytes
TOS
TTL
Source Address
Destination Address
Microsoft's Tracert
802.3 Ethernet Packet Format
Bytes: 7
1
6
MAC
Destination
Address
6
2
MAC
Source
Address
20
20
6-1460
4
IPv4
TCP
Data + Padding
CRC
IPv4 Header

Contains two addresses
 4B
Source Address
 4B Destination Address
 4B = 32b = 4.295 G potential addresses

Example address
 10001011

01001110 01000010 11010011
Dotted Decimal Format simplifies
 x.x.x.x
 Treat
each byte as Base2 number, write in Base10
 Above number simplifies to 139.78.66.211
IP Header

Alpha-numeric name simplifies further
 es302.ceat.okstate.edu
 Domain

Name Servers convert to numerical
All OSU Stillwater addresses are of form
 139.78.0.0

to 139.78.255.255
IP addresses & alpha-numeric names are
effectively backwards
 139.78.66.211
mapped to
es302.ceat.okstate.edu
IP vs Ethernet Addresses

Ethernet has a flat address space
 Similar
to Social Security Number
 Adjacent
 Huge
look up tables required to avoid flooding
 Need

#'s nearby or on other side of globe?
70.37 trillion entries
IP has a hierarchical address space
 Packet
delivery similar to Mail delivery
 Adjacent
 Reduces
 Don't
IP addresses frequently nearby
size of look up tables
need 4.295 billion entries
ISP Router Overload
Source:
1 October 2007
Network World
Fall 2011
Level3
BGP entries
375,550 IPv4
7,210 IPv6
Peak Traffic
8.0 Tbps IPv4
500 Mbps IPv6
ISP Router Overload

Core BGP entries as of 19 August 2014
 IPv4
about 520,400
 IPv6 about 18,300

2nd week of August
 Caused
some problems
 Some routers had 512,000 entry limit
source:
bgp.potaroo.net
Network World , 13Aug2014, "Internet outages expected to abate as routers are modified, rebooted"
ISP BGP Table
source: http://bgp.potaroo.net/index-bgp.html
TCP Header
4 Bytes
Source Port
Destination Port
Sequence Number
ACK Number
Window
Checksum