Download COSC4377 TCP vs UDP – Example Statistics

10/17/2013
Lennart Johnsson
2013‐10‐17
COSC4377
COSC4377
Lecture 16
Lennart Johnsson
2013‐10‐17
COSC4377
TCP vs UDP – Example Statistics
Trace
Sample
UDP/TCP Ratio pkts bytes flows
Total IP Traffic (pkts/bytes/flows)
CAIDA‐OC48 08‐2002 0.11
0.03
0.11
(1371M/838GB/79M)
01‐2003 0.12
0.05
0.27
(463M/267GB/26M)
GigaSUNET 04‐2006 0.06
0.02
1.06
(422M/294GB/9M)
11‐2006 0.08
0.03
1.45
06‐2008 0.14
0.05
1.43
(4427M/2279GB/197M)
02‐2009 0.19
0.07
2.34
(1922M/1410GB/110M)
OptoSUNET 01‐2009 0.21
0.11
3.09
(1100M/657GB/41M)
02‐2009 0.20
0.11
2.63
CAIDA‐
OC192
http://www.caida.org/research/traffic‐analysis/tcpudpratio/
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Internet Private Addresses (IPv4)
RFC1918 IP address range
number of addresses
classful
description
largest CIDR
block (subnet host id size
mask)
24‐bit block
10.0.0.0 ‐
10.255.255.255
16,777,216
single class A network
10.0.0.0/8 (255.0.0.0)
20‐bit block
172.16.0.0 ‐
172.31.255.255
1,048,576
16 contiguous 172.16.0.0/12 class B 20 bits
(255.240.0.0)
network
192.168.0.0 ‐
16‐bit block
65,536
192.168.255.255
256 contiguous class C network
24 bits
192.168.0.0/1
6 16 bits
(255.255.0.0)
Address ranges reserved by IANA for Private Addresses
http://en.wikipedia.org/wiki/Private_network
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NAT: network address translation
rest of
Internet
local network
(e.g., home network)
10.0.0/24
10.0.0.1
10.0.0.4
10.0.0.2
138.76.29.7
10.0.0.3
all datagrams leaving local
network have same single
source NAT IP address:
138.76.29.7,different source
port numbers
Slide from Kurose & Ross, 6th Ed datagrams with source or
destination in this network
have 10.0.0/24 address for
source, destination (as usual)
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NAT: network address translation
motivation: local network uses just one IP address as far as outside world is concerned:
 range of addresses not needed from ISP: just one IP address for all devices
 can change addresses of devices in local network without notifying outside world
 can change ISP without changing addresses of devices in local network
 devices inside local net not explicitly addressable, visible by outside world (a security plus)
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Slide from Kurose & Ross, 6th Ed COSC4377
Lennart Johnsson
2013‐10‐17
NAT: network address translation
implementation: NAT router must:
 outgoing datagrams: replace (source IP address, port #) of every outgoing datagram to (NAT IP address, new port #)
. . . remote clients/servers will respond using (NAT IP address,
new port #) as destination addr
 remember (in NAT translation table) every (source IP address, port #) to (NAT IP address, new port #) translation pair
 incoming datagrams: replace (NAT IP address, new port #) in dest fields of every incoming datagram with corresponding (source IP address, port #) stored in NAT table
Slide from Kurose & Ross, 6th Ed 6
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NAT: network address translation
NAT translation table
WAN side addr
LAN side addr
2: NAT router
changes datagram
source addr from
10.0.0.1, 3345 to
138.76.29.7, 5001,
updates table
1: host 10.0.0.1
sends datagram to
128.119.40.186, 80
138.76.29.7, 5001 10.0.0.1, 3345
……
……
S: 10.0.0.1, 3345
D: 128.119.40.186, 80
10.0.0.1
1
2
S: 138.76.29.7, 5001
D: 128.119.40.186, 80
10.0.0.4
138.76.29.7
S: 128.119.40.186, 80
D: 138.76.29.7, 5001
S: 128.119.40.186, 80
D: 10.0.0.1, 3345
3
10.0.0.2
4
10.0.0.3
4: NAT router
changes datagram
dest addr from
138.76.29.7, 5001 to 10.0.0.1, 3345
3: reply arrives
dest. address:
138.76.29.7, 5001
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Slide from Kurose & Ross, 6th Ed COSC4377
Lennart Johnsson
2013‐10‐17
NAT: network address translation
16‐bit port‐number field:  60,000 simultaneous connections with a single LAN‐side address!
NAT is controversial:
 routers should only process up to layer 3
 violates end‐to‐end argument
• NAT possibility must be taken into account by app
designers, e.g., P2P applications
 address shortage should instead be solved by IPv6
Slide from Kurose & Ross, 6th Ed 8
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NAT traversal problem
• client wants to connect to server with address 10.0.0.1
– server address 10.0.0.1 local to LAN (client can’t use it as destination addr)
– only one externally visible NATed address: 138.76.29.7
10.0.0.1
client
?
10.0.0.4
138.76.29.7
• solution1: statically configure NAT to forward incoming connection requests at given port to server
NAT
router
– e.g., (123.76.29.7, port 2500) always forwarded to 10.0.0.1 port 25000
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Slide from Kurose & Ross, 6th Ed Lennart Johnsson
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COSC4377
NAT traversal problem
solution 2: Universal Plug and Play (UPnP) Internet Gateway Device (IGD) Protocol. Allows NATed host to:
 learn public IP address (138.76.29.7)
 add/remove port mappings (with lease times)
i.e., automate static NAT port map configuration
10.0.0.1
IGD
NAT
router
For more info on UPnP, IGD and Port Control Protocol (PCP) see IETF Working Grop docs
http://tools.ietf.org/html/draft‐ietf‐pcp‐upnp‐igd‐interworking‐04
Slide from Kurose & Ross, 6th Ed 10
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NAT traversal problem
solution 3: relaying (used in Skype)
 NATed client establishes connection to relay
 external client connects to relay
 relay bridges packets between to connections
2. connection to
relay initiated
by client
1. connection to
relay initiated
by NATed host
3. relaying
established
client
138.76.29.7
10.0.0.1
NAT
router
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Slide from Kurose & Ross, 6th Ed Lennart Johnsson
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COSC4377
Chapter 4: outline
4.1 introduction
4.2 virtual circuit and datagram networks
4.3 what’s inside a router
4.4 IP: Internet Protocol
–
–
–
–
datagram format
IPv4 addressing
ICMP
IPv6
Slide from Kurose & Ross, 6th Ed 4.5 routing algorithms
 link state
 distance vector
 hierarchical routing
4.6 routing in the Internet
 RIP
 OSPF
 BGP
4.7 broadcast and multicast routing
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ICMP: internet control message protocol
• used by hosts & routers to communicate network‐
level information
– error reporting: unreachable host, network, port, protocol
– echo request/reply (used by ping)
• network‐layer “above” IP:
– ICMP msgs carried in IP datagrams
• ICMP message: type, code plus first 8 bytes of IP datagram causing error
Type
0
3
3
3
3
3
3
4
Code
0
0
1
2
3
6
7
0
8
9
10
11
12
0
0
0
0
0
description
echo reply (ping)
dest. network unreachable
dest host unreachable
dest protocol unreachable
dest port unreachable
dest network unknown
dest host unknown
source quench (congestion
control - not used)
echo request (ping)
route advertisement
router discovery
TTL expired
bad IP header
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Slide from Kurose & Ross, 6th Ed COSC4377
Lennart Johnsson
2013‐10‐17
Traceroute and ICMP
 source sends series of UDP segments to dest
 first set has TTL =1
 second set has TTL=2, etc.
 unlikely port number
 when nth set of datagrams arrives to nth router:
 router discards datagrams
 and sends source ICMP messages (type 11, code 0)
 ICMP messages includes name of router & IP address
3 probes
 when ICMP messages arrives, source records RTTs
stopping criteria:
 UDP segment eventually
arrives at destination host
 destination returns ICMP
“port unreachable”
message (type 3, code 3)
 source stops
3 probes
3 probes
Slide from Kurose & Ross, 6th Ed 14
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Lennart Johnsson
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COSC4377
Chapter 4: Network Layer
• 4. 1 Introduction
• 4.2 Virtual circuit and datagram networks
• 4.3 What’s inside a router
• 4.4 IP: Internet Protocol
–
–
–
–
Datagram format
IPv4 addressing
ICMP
IPv6
• 4.5 Routing algorithms
– Link state
– Distance Vector
– Hierarchical routing
• 4.6 Routing in the Internet
– RIP
– OSPF
– BGP
• 4.7 Broadcast and multicast routing
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Slide from Kurose & Ross, 6th Ed COSC4377
Lennart Johnsson
2013‐10‐17
More than 4 billion devices already share addresses
http://www.youtube.com/watch?feature=player_embedded&v=‐Uwjt32NvVA
IPv6 is essential to the continued health and growth of the Internet and that by allowing all devices to talk to each other directly, IPv6 enables new innovative services
http://www.google.com/ipv6/index.html
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IPv6: motivation
initial motivation: 32‐bit address space soon to be completely allocated. additional motivation:
 header format helps speed processing/forwarding
 header changes to facilitate QoS IPv6 datagram format:  fixed‐length 40 byte header
 no fragmentation allowed
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Slide from Kurose & Ross, 6th Ed Lennart Johnsson
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COSC4377
IPv6 datagram format
priority: identify priority among datagrams in flow
flow Label: identify datagrams in same “flow.”
(concept of“flow” not well defined).
next header: identify upper layer protocol for data
IPv4
IPv6
32 bits
32 bits
ver
pri
ver
flow label
payload len
next hdr
source address
(128 bits)
destination address
(128 bits)
hop limit
head.
len
type of
service
16‐bit identifier
time to
live
length
flgs
upper
layer
fragment
offset
header
checksum
32 bit source IP address
32 bit destination IP address
Options (if any)
data
Slide from Kurose & Ross, 6th Ed data (variable length,,typically a TCP or UDP segment)
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The Internet Protocol ‐ History
• History of the Internet Protocol
– Internet Protocol version 4 (IPv4)
•
•
•
•
Developed for the original Internet (ARPANET) in 1978
4 billion addresses
Deployed globally & well entrenched
Allocated based on documented need
– Internet Protocol version 6 (IPv6)
• Design began in 1993 when IETF forecasts showed IPv4 depletion between 2010 and 2017
• 340 undecillion addresses
• Completed, tested, and available since 1999
• Used and managed similar to IPv4
https://www.arin.net/knowledge/v4_deplete_v6_adopt.pdf
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IPv4 and IPv5 Comparison
https://www.arin.net/knowledge/v4_deplete_v6_adopt.pdf
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Other changes from IPv4
• checksum: removed entirely to reduce processing time at each hop
• options: allowed, but outside of header, indicated by “Next Header” field
• ICMPv6: new version of ICMP
– additional message types, e.g. “Packet Too Big”
– multicast group management functions
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Slide from Kurose & Ross, 6th Ed COSC4377
Lennart Johnsson
2013‐10‐17
IPv6 addresses RFC4291
• “Full” format x:x:x:x:x:x:x:x, where the 'x's are one to four hexadecimal digits of the eight 16‐bit pieces of the address. Examples: ABCD:EF01:2345:6789:ABCD:EF01:2345:6789
2001:DB8:0:0:8:800:200C:417A 22
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IPv6 addresses RFC4291
• “Compressed” format Examples: 2001:DB8:0:0:8:800:200C:417A a unicast address
Compressed 2001:DB8::8:800:200C:417A FF01:0:0:0:0:0:0:101 a multicast address Compressed FF01::101 0:0:0:0:0:0:0:1 the loopback address Compressed ::1 0:0:0:0:0:0:0:0 the unspecified address
Compressed :: 23
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IPv6 addresses RFC4291
• Alternative format Examples: 0:0:0:0:0:0:13.1.68.3 0:0:0:0:0:FFFF:129.144.52.38 or in compressed form: ::13.1.68.3 ::FFFF:129.144.52.38 24
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IPv6 addresses RFC4291
• Prefix representation (like CIDR for IPv4) Example: 60‐bit prefix 20010DB80000CD3 (hexadecimal):
2001:0DB8:0000:CD30:0000:0000:0000:0000/60 2001:0DB8::CD30:0:0:0:0/60 2001:0DB8:0:CD30::/60 25
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Lennart Johnsson
2013‐10‐17
IPv6 – How to obtain an address?
• IPv6 defines both a stateful and stateless address auto‐
configuration mechanism. – Stateless auto‐configuration requires no manual configuration of hosts, minimal (if any) configuration of routers, and no additional servers. The stateless mechanism allows a host to generate its own addresses using a combination of locally available information and information advertised by routers. Routers advertise prefixes that identify the subnet(s) associated with a link, while hosts generate an "interface identifier" that uniquely identifies an interface on a subnet. An address is formed by combining the two. In the absence of routers, a host can only generate link‐local addresses. However, link‐local addresses are sufficient for allowing communication among nodes attached to the same link. RFC 2462, December 1998.
– In Stateful auto‐configuration (DHCPv6), hosts obtain interface addresses and/or configuration information and parameters from a server. Servers maintain a database that keeps track of which addresses have been assigned to which hosts. The stateful auto‐configuration protocol allows hosts to obtain addresses, other configuration information or both from a server. Stateless and stateful auto‐configuration complement each other. For example, a host can use stateless auto‐configuration to configure its own addresses, but use stateful auto‐configuration to obtain other information. RFC 3315, July 2003.
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Transition from IPv4 to IPv6
• not all routers can be upgraded simultaneously
– no “flag days”
– how will network operate with mixed IPv4 and IPv6 routers? • tunneling: IPv6 datagram carried as payload in IPv4 datagram among IPv4 routers
IPv4 header fields
IPv4 source, dest addr
IPv6 header fields
IPv6 source dest addr
IPv4 payload
UDP/TCP payload
IPv6 datagram
IPv4 datagram
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Slide from Kurose & Ross, 6th Ed Lennart Johnsson
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COSC4377
Tunneling
IPv4 tunnel
connecting IPv6 routers
A
B
IPv6
IPv6
A
B
C
IPv6
IPv6
IPv4
logical view:
E
F
IPv6
IPv6
D
E
F
IPv4
IPv6
IPv6
physical view:
Slide from Kurose & Ross, 6th Ed 28
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Tunneling
IPv4 tunnel
connecting IPv6 routers
A
B
IPv6
IPv6
logical view:
A
B
C
IPv6
IPv6
IPv4
E
F
IPv6
IPv6
D
E
F
IPv4
IPv6
IPv6
physical view:
flow: X
src: A
dest: F
data
A-to-B:
IPv6
src:B
dest: E
src:B
dest: E
Flow: X
Src: A
Dest: F
Flow: X
Src: A
Dest: F
data
data
B-to-C:
IPv6 inside
IPv4
B-to-C:
IPv6 inside
IPv4
flow: X
src: A
dest: F
data
E-to-F:
IPv6
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Slide from Kurose & Ross, 6th Ed COSC4377
Lennart Johnsson
2013‐10‐17
IPv6 Adoption
• Three drivers of IPv6 growth (Akamai)
– 1) Content availability. More of our customers are opting in to have their sites, content, and applications permanently available "dual‐stacked" (i.e., available over both IPv6 and IPv4). – 2) Availability of IPv6 from access network providers. Over the past year, some of the largest growth ia coming from major ISPs within the U.S., as they roll out production IPv6 support to their end‐users, including Verizon Wireless, AT&T, and Comcast. This is on top of some ISPs in Europe and Asia that have had IPv6 deployed in production for a few years, as well as a long tail of thousands of network providers, universities, and research labs around the globe. More IPv6 growth will come as these networks extend their IPv6 deployments and as other networks join them.
– 3) End‐user device support. While most recent desktop and laptop operating systems and client software supports IPv6, many home routers and gateways didn't have support until very recently. Many embedded devices and consumer electronics are also slow to gain IPv6 support, with the notable exception of many 4G LTE smart phones. This has been one of the limiting factors to users whose network providers have rolled out IPv6 capabilities, and as users upgrade devices over the next few years, this should cause a significant increase in IPv6 usage.
https://blogs.akamai.com/2012/07/a‐data‐driven‐view‐of‐ipv6‐adoption.html
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IPv6 adoption
• The U.S. Government has put in place an IPv6 mandate that requires all government agencies to have their public facing websites and email services available over IPv6 by September 30th, 2012.
• Over 1,800 U.S Government websites are expected to be on IPv6 by the mandate deadline. http://www.enterprisenetworkingplanet.com/netsp/u.s.‐government‐
paves‐the‐way‐to‐ipv6‐with‐mandate‐compliance.html
• Planning Guide/Roadmap Toward IPv6 Adoption within the U.S. Government , Strategy and Planning Committee Federal Chief Information Officers Council, http://www.ipv6forum.com/dl/presentations/USGv6Roadmap.pdf
• “while IPv6 is small today, it's imperative that the technology is rolled out now”, Akamai, September 28, 2012, http://www.enterprisenetworkingplanet.com/netsp/u.s.‐government‐paves‐the‐way‐to‐ipv6‐with‐
mandate‐compliance.html
• A 2014 IPv6 US Government mandate will require that the internal enterprise infrastructures of U.S. Government agencies are running IPv6.
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IPv6 Adoption
https://www.arin.net/
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IPv6 Adoption
https://blogs.akamai.com/2012/07/a‐data‐driven‐view‐of‐ipv6‐adoption.html
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IPv6 connectivity for Google users
IPv6 Enabled Web browsers
http://www.vyncke.org/ipv6status/compare.php?metric=p&countries=ch,ro,fr,us,gb
http://www.google.com/ipv6/statistics.html
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Percentage of ASs announcing IPv6 prefixes
http://www.ipv6actnow.org/info/statistics/
Lennart Johnsson
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IPv6 Adoption
IPv6 Launch Day
June 6, 2012
http://www.worldipv6launch.org/measurements/
http://www.worldipv6launch.org/measurements/
https://blogs.akamai.com/2012/07/
a‐data‐driven‐view‐of‐ipv6‐adoption.html
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