Transcript LIDO - itk.ilstu.edu

LIDO Telecommunications Essentials®
Part 2
Data Networking and the Internet
QoS in Converged Networks
The Internet and IP Infrastructures
1
Contents
See also Reading Materials-Forouzan Ch 22
Routing Protocols and Ch 29 Multimedia
LIDO
2
QoS in Converged Networks
LIDO
QoS in PSTN
• In traditional telephony, quality of service for each
and every phone call is guaranteed by the constant
availability of dedicated bandwidth.
• Most digitally encoded call paths on the PSTN use
the same codec, G.711, so transcoding isn’t
necessary.
• Almost no processing bottlenecks will be found on
the PSTN, and since the system isn’t generally
packet-based, there is almost never degradation in
perceived call quality as a result of congestion.
LIDO
QoS in Packet Networks
• When bandwidth availability drops, as more packets
are sent on the network, throughput slows.
• Until a certain breaking point, bandwidth availability
can be compromised while still allowing data
through; the transmission just slows down.
• Some applications tolerate congestion and slow
• throughput better than others. The more tolerance an
application has, the higher its error budget is said to
be.
LIDO
Latency
• Slowness of transmission—latency—is the enemy
of multimedia traffic
• Solution to the latency problem: technique that
allows local and end-to-end guarantees of
bandwidth and prioritization of real-time traffic
over less sensitive traffic.
• QoS protocols and standards: 802.1p, 802.1q
VLAN, DiffServ, RSVP, and MPLS.
•
LIDO
Call-quality scoring
• Mean opinion score (MOS): Listeners hear sound
samples from calls of varying quality, recorded
during different sets of network conditions.
• Everbody rates the sample’s quality on a scale of
1 to 5, with 5 being the best quality.
• G.711’s highest perceived quality score is 4.4. By
comparison, G.729A’s is only 3.6.
• See next figure:
LIDO
Don’t use G.729A across a fast Ethernet link because
the quality perceived by users will be lower than it
ought to be.
LIDO
Noise
• One of the biggest factors in perceived quality is
noise.
• Additive noise is the unwanted signals that
accompany all transmissions of sound.
Subtractive noise is an interruption or reduction of
the sound transmission, such as that caused by
packet loss.
LIDO
Noise
• Multimedia traffic, such as VoIP does introduce new
kinds of noise, broadening the traditional definition
to include everything shown in the next figure.
• While noise cannot be entirely avoided, it should be
minimized.
• One of QoS’s roles is to help us avoid situations in
which poor service at the lower layers of the network
results in additive or subtractive noise.
LIDO
Noise
LIDO
Class of Service versus Quality of Service
LIDO
Standards
LIDO
Latency, Packet Loss, and Jitter
• Latency (also called lag) is caused primarily by slow network links.
• End-to-end latency, in the case of VoIP, is the time it takes from the instant the caller
utters something until the time the receiver hears that utterance.
• Round-trip latency less than 150 ms is not immediately noticeable, but latency higher
than 150 ms is discouraged, and latency higher than 300 ms is considered
unacceptable.
• Latency has the following effects on telephony and video applications:
• Can slow down the human conversation
• Can result in caller and receiver unintentionally interrupting each other
• Can worsen another Quality-of-Service problem: echo
• Can cause synchronization delays in conference-calling applications
The best ways to beat latency are to use low-packet-interval codecs and maintain fast network
links, because QoS protocols alone cannot directly improve latency’s impact. That is, they
can’t speed up your network.
LIDO
Sources of Latency
• Framing and packetization
• • Software processing and packet loss concealment (PLC; replacing the
sound that would presumably have been produced by a packet that was
lost with sound that is predicted based on the sequence of packets
received before it and (when extensive buffering is used) after it)
• Jitter buffering
• Routing and firewall traversal
• Transcoding
• Media access and network interfacing
Minimizing latency is an important way to maximize the multimedia
(VOIP) network’s perceived quality of service.
LIDO
Cont.
• The two biggest sources of latency are
framing/packetization, which can add up to 30 ms
of latency, and routing, which can add 5–50 ms
per hop.
• Another big contributor is transcoding (See next
figure)
LIDO
Transcoding Latency in ms
LIDO
Packet Loss
• Even with Packet Loss Concealment (PLC) in
force, packet loss rates on a VoIP network should
be kept below 1%.
• A drawback of PLC is that it can increase latency.
• Experimentation with PLC-equipped codecs
should be done to determine how negative the
latency-impact PLC is in your VoIP network.
LIDO
Jitter
• It’s the variation in latency time from one packet to the next.
• It causes packets to arrive out of order, leaving gaps in the framing
sequence of the voice/video signal.
• Jitter is at its worst when voice traffic must travel through several routers
on the network.
• Different routers, especially those at ISPs, may be configured to queue
and forward different kinds of traffic in different ways.
• Others may be loadbalancing, which can contribute to jitter.
• The main goal of QoS protocols is to eliminate jitter.
• Devices called jitter buffers, in endpoints and VoIP servers, can
minimize the effect of jitter, too. But, like PLC measures, they do so by
increasing latency.
LIDO
Class of Service (COS)
• CoS systems work to prioritize traffic on a single data link.
• While QoS refers to the greater network, CoS refers to only a
single data link.
• The key difference is that CoS is a single-link approach, while
QoS is an end-to-end approach.
• Class of Service systems define per-hop behavior, so they
cannot guarantee a service
• level in terms of capacity or speed.
• Two key standards support CoS:
802.1p/ToS
DiffServ
LIDO
802.1p
• 802.1p uses a 3-bit portion of the Ethernet packet header to
classify each packet into a particular level of precedence on
the local data link.
• Type of Service (ToS) is the portion of the IP packet
header that stores the same precedence information.
• If your VoIP network will be more than 70% data-to-voice
and unlikely to reach capacity, packet prioritization
techniques like LAN-oriented 802.1p and its WAN cousin
DiffServ are adequate.
• The next table lists the suggested, generic service names.
LIDO
Suggested 802.1p classes
LIDO
Differentiated Services (DiffServ).
. When a packet reaches the edge of the network,
either from an endpoint or from a
• remote network, DiffServ tags that packet’s ToS
header based on the priority established for that
packet by policy.
• Once admitted into a DiffServ-equipped WAN,
however, all subsequent router hops must enforce
the priority set by the edge router that admitted
the packet.
LIDO
Policy servers
• Common Open Policy Service, or COPS, is a way of
storing and querying centralized
• policy information on the network.
• DiffServ can use COPS to obtain its marching orders for
how to handle traffic coming into the network.
• In a COPS scheme, a centralized server called the policy
server contains a policy record of traffic shaping and
prioritization preferences that DiffServ or another CoS/QoS
mechanism can retrieve.
• Another IETF recommendation, LDAP (Lightweight
Directory Access Protocol), can also be used as the basis of
a policy server.
LIDO
DiffServ Code Points (DSCP)
• DSCP classes are IP packet headers DiffServ
associates with different levels of importance.
• Since they’re 6 bits in length, DSCPs can be used to
define quite a wide scale of possible service levels.
Most implementations support only 3 bits, replacing
the 3 bits in IP’s ToS header.
• DSCP per-hop behaviors break down into three basic
groups, interchangeably called PHB classes, traffic
classes, or DSCP classes:
LIDO
DSCP Classes
• AF Assured Forwarding, a highly expedient
DSCP class, sometimes used to tag signaling
packets such as H.245/H.225 and SIP packets.
• EF Expedited Forwarding, the most expedient
DSCP class, used to tag packets carrying actual
sound data.
• BE Best Effort, a nonexpedient DSCP class, used
to tag non-voice packets. Many DiffServ decision
points don’t use BE.
LIDO
802.1q VLAN
•
•
•
•
•
•
LIDO
Broadcast domain per network segment means that when a packet comes across the
segment destined for a local host whose hardware (MAC) address has not yet been
resolved (ARPed) and associated with a certain switch port on the Ethernet segment, a
broadcast to all ports is done in order to find a host with the right MAC address that’s
supposed to receive the packet.
Once the port with the correct recipient is found, an ARP record is recorded in the switch
so that all future traffic destined for that MAC address can go to that port rather than
being broadcast.
One problem is that the broadcast traffic can be a waste of bandwidth.
Another problem is that, when broadcasts occur, every device on the network can receive
them, which is a potential security hazard.
802.1q VLAN (virtual LAN) is a way to separate Ethernet traffic logically, secure
Ethernet broadcast domains, organize the network by separating network protocols into
their own VLANs
Each VLAN is a logically separate broadcast domain—even if it coexists with other
VLANs on the same physical segment.
Layer 2 Switching
• With most vendors’ Ethernet equipment, to create
VLANs, each switch port is assigned a VLAN tag—a
numeric identifier that is unique within the network.
• This tag identifies the VLAN in which that port
participates. Once the tag is assigned, the device
connected to that port will receive traffic only from
the assigned VLAN and will be able to send traffic
only to the assigned VLAN.
LIDO
VLANs
LIDO
Layer 3 Switching
• Sometimes Ethernet switches can be used to groom,
inspect, or route traffic.
• Layer 3 switching accomplishes some router-like
activities: queuing, routing, and packet-inspection.
• It can be used to shape the traffic on the data link
based on each packet’s
• characteristics.
• For example, it’s possible to drop all non-voice
traffic by filtering protocol types (UDP, TCP, etc.)
and port numbers.
LIDO
Quality of Service
• Intserv (Integrated Services) is an IETF recommendation for provided dedicated
bandwidth to individual flows, or media channels, on an IP network.
• The media channels are referred to by their sockets
• RSVP (Resource Reservation Protocol) is the recommended signaling protocol
for
• Intserv.
• The purpose of RSVP is to ensure that the network has enough bandwidth to
support
• each call, before any data is passed through the media channel.
• RSVP adds decision-making points to the core network, increasing the
processing overhead requirement on core routers.
• RSVP is the perfect solution for bandwidth allocation over slower links, because
it guarantees availability for each RTP stream, rather than giving a “best effort.”
LIDO
Example: Slow Links Between Routers
LIDO
H.323
1. H.245 negotiates the codec and establishes RTP sockets that will be used on either end of
the media channel. These two sockets—the IP addresses and port numbers—together
form the session ID that RSVP will use to refer to this RTPsession. RSVP calls the
session ID a flow ID.
2. The gateway router for the caller, B, sends a path message (PM) to the next hop, B, along
the way to the remote gateway router, D. This PM will continue to be forwarded from
one hop to the next in order to establish the QoS path.
3. B records the latency added as the PM reaches it, along with minimum latency, jitter
ranges the router is willing to guarantee. Then, the PM is sent to the next router along the
path, in this case, C.
4. C records the latency added as the PM reaches it, along with minimum latency, jitter
ranges the router is willing to guarantee. Then, the PM is sent to the next router along the
path, in this case, D.
5. When the PM reaches the remote gateway router, D, cumulative latency and jitter are
calculated. The result is a profile call the ADSPEC, and the portion of the RSVP header
used to accumulate QoS data during the PM is called the ADSPEC header.
LIDO
Link delays and maximum jitter readings are
recorded for each hop.
LIDO
RSVP
• When the remote gateway router reads the
ADSPEC data and makes the determination, it
can do one of two things:
• Give up, resulting in a busy tone for the caller, or
• Trigger the reserve message (RM) to set up the
traffic contracts with each router in order to
reserve bandwidth for the call.
LIDO
Reserve Messages (RM)
1. The remote gateway router (D) sends the reserve
message to the previous router in the path. The
sender and receiver RTP sockets are confirmed, and a
contract is established for the timeout value in
seconds, sustained throughput, and peak throughput
required by the RTP session.
2. The previous router in the path (C) sends a similar
RM to its previous router in the path (B).
3. Router B sends router A another RM.
LIDO
RM Confirmation
1. Router A sends a reserve confirm message to router
B if it agrees to guarantee the bandwidth and timeout
values requested, or a rejection message if not.
2. Router B sends router C a similar response. If the
first response, from router A, was a rejection, then all
subsequent responses will be rejections as well.
3. Router C sends router D a similar response. If the
first or second was a rejection, then this response will
be a rejection as well.
LIDO
RSVP Service Levels
• RSVP defines three service levels in RFC 2211:
• Best Effort
A class of service that has no QoS measures whatsoever. On
Cisco routers, the fair-queuing feature is used to enable Best
Effort service.
• Controlled Load
Allows prioritization of traffic over multiple routers like DiffServ
but includes core routers in the decision-making process.
• Guaranteed
No packets will be lost, bandwidth will be constant, and delay
will be within the prescribed ranges set up in the traffic
contract.
LIDO
MPLS
•
•
•
•
•
LIDO
MPLS bears great similarity to ATM signaling but borrows heavily from RSVP. Unlike
ATM, which incurs a 25% overhead on TCP/IP traffic (called the ATM “cell tax”),
MPLS doesn’t use its own framing format, just its own labeling format.
The purpose of MPLS labels is to identify the paths and priorities associated with each
packet. The paths correspond to the media channel of the VoIP call, while the priorities
respond to the QoS level of service negotiated for those channels, just like RSVP.
But like DiffServ, MPLS can use a dumb network core. If a packet is carrying a label, all
a router has to do is send it along the labeled path, rather than making a redundant
assessment of the packet’s payload.
MPLS inserts itself partially in layer 2 and partially in layer 3 on the OSI model. Its
frame header sits between the IP header and the Ethernet header on an Ethernet network
or between the label header and the payload on an ATM network.
What’s important to know is this: MPLS resides outside the reach of the network
protocol, like 802.1p. framing protocol (Ethernet framing, for example). This makes it
invisible to the higher layers.
Multiprotocol Label Switching
• Multiprotocol Label Switching (MPLS)
– Born of Cisco’s tag switching, designed with large-scale WAN
in mind, MPLS was proposed by the Internet Engineering Task
Force (IETF) in 1997.
– Core specifications for MPLS were completed by IETF in the
fall of 2000.
– By plotting static paths through an IP network, MPLS gives
service providers the traffic engineering capability they require
while also building a natural foundation for VPNs.
• Traffic engineering allows service providers to do two
things: control quality of service (QoS) and optimize
network resource utilization.
– MPLS also has the potential to unite IP and optical switching
under one route-provisioning umbrella.
LIDO
40
How MPLS Works
• “MP” means it is multiprotocol. MPLS is an
encapsulating protocol, it can transport a multitude of
other protocols.
• “LS” indicates that the protocols being transported are
encapsulated with a label that is swapped at each hop.
– A label is a number that uniquely identifies a set of data flows
on a particular link or within a particular logical link.
– The labels are of local significance only – they must change as
packets follow a path – hence the “switching” part of MPLS.
LIDO
41
How MPLS Works
• MPLS can switch a frame from any kind of layer-2 link
to any other kind of layer-2 link without depending on
any particular control protocol.
• ATM can only switch to and from ATM and can use only
ATM signaling protocols, such as PNNI (Private
Network-to-Network Interface) and IISP (Interim
Interface Signaling Protocol).
LIDO
42
MPLS
• Since IP is a connectionless protocol, it cannot
guarantee that network resources will be available.
• Additionally, IP sends all traffic between the same
two points over the same route. During busy periods,
therefore, some routes get congested while others
remain underutilized.
– One key difference between MPLS and IP is that packets
sent between two end points can take different paths, based
on different MPLS labels.
LIDO
• Without explicit control over route assignments, the
provider has no way to steer excess traffic over less
busy routes.
43
MPLS
LIDO
• MPLS tags or adds a label to IP packets so they can
be steered over the Internet along predefined routes.
• MPLS also adds a label identifying the type of traffic,
path and destination.
• This allows routers to assign explicit paths to various
classes of traffic.
• Using explicit routes, service providers can reserve
network resources for high-priority or delay-sensitive
flows, distribute traffic to prevent network hot spots
and pre-provision backup routes for quick recover
from outages.
44
MPLS
• An MPLS network is comprised of a mesh of label
switch routers (LSRs)
– LSRs are MPLS-enabled routers and/or MPLS-enabled ATM
switches.
• As each packet enters the network, an ingress LSR
assigns it a label based on its destination, VPN
membership, type-of-service bits, etc.
• At each hop, an LSR uses the label to index a forwarding
table. The forwarding table assigns each packet a new
label, and directs the packet to an output port. To
promote scaling, labels have only local significance
• As a result, all packet with the same label follow the
same label switched path (LSPs) through the network.
LIDO
45
LIDO
Multiprotocol Label Switching
(
)
Stallings, High-Speed Networks
LIDO
47
How MPLS Works
LIDO
• With MPLS you can support all applications on an IP
network without having to run large subsets of the
network with completely different transport
mechanisms, routing protocols, and addressing plans.
• Offers the advantages of circuit-switching
technology, including bandwidth reservation and
minimized delay variations for voice and video
traffic, plus all the advantages of existing best-effort,
hop-by-hop routing.
• Allows service providers to create VPNs with the
flexibility of IP but the QoS of ATM.
48
MPLS Labels
• MPLS supports three different types of label formats.
– On ATM hardware it uses the well-defined Virtual Channel
Identifier (VCI) and Virtual Path Identifier (VPI) labels.
– On frame relay hardware, it uses a Data Link Connection
Identifier (DLCI) label.
– Elsewhere, MPLS uses a new, generic label known as a Shim,
which sits between layers 2 and 3.
• Because MPLS allows the creation of new label formats
without requiring change in routing protocols, extending
technology to new optical transport and switching should
be straightforward.
LIDO
49
MPLS Label Stacking
LIDO
• Another powerful attribute of MPLS is Label
Stacking.
• Label stacking allows LSRs (label switched router) to
insert an additional label at the front of each labeled
packet, creating an encapsulated tunnel that can be
shared by multiple LSPs (label switched paths).
• At the end of the tunnel, another LSR pops the label
stack, revealing the inner label.
• An optimization in which the next-to-last LSR peels
off the outer label is known in IETF documents as
“penultimate hop popping”.
50
MPLS Label Stacking
• ATM has only one level of stacking, virtual channels
inside of virtual paths.
• MPLS supports unlimited stacking.
– An enterprise could use label stacking to aggregate multiple
flows of its own traffic before passing it on to the access
provider
– The access provider could aggregate traffic from multiple
enterprises before handing it to a backbone provider
– The backbone provider could aggregate traffic yet again before
passing it off to a wholesale carrier.
LIDO
51
MPLS Label Stacking
• Service providers could use label stacking to
merge hundreds of thousands of LSPs into a
relatively small number of backbone tunnels
between points of presence.
• Fewer tunnels means smaller route tables, making
it easier for providers to scale the network core.
LIDO
52
MPLS Evolution
• However, the IETF and the MPLS Forum still have
issues to resolve.
– They must reconcile MPLS with DiffServ, so that type-ofservice markings can be transferred from IP headers to MPLS
labels and interpreted by LSRs in a standard manner.
– They must clarify how MPLS supports virtual private networks.
• Two models exist, one based on BGP and the other on virtual routers.
• Protocols like RSVP, OSPF, and IS-IS must be extended
to realize the full benefit of MPLS.
LIDO
53
MPLS Evolution
• Major efforts are underway to adapt the control plane of
MPLS (e.g., OSPF, IS-IS, LDP, etc) to direct the routing
of optical switches, not just LSRs (label switched
routers).
• This will allow optical switches, LSRs and regular IP
routers to recognize each other.
• The same routing system can control optical paths in the
DWDM core, LSPs (label switched paths) across the
MPLS backbone and any IP routers at the edge of the
network.
LIDO
54
MPLS Evolution
• With MPLS, service providers can simplify their
operational procedures, deliver more versatile IP
services and sign meaningful SLAs.
LIDO
55
Key Internet Developments
RTP, RTCP, RTSP (F.Ch28
Multimedia A/V, VOIP)
• RTP (Real-Time Transport Protocol) for audio,
video, etc.
• RTCP - Real-Time Control Protocol
• RTP & RTCP standardized by ITU H.225
• RTSP - Real-Time Streaming Protocol
• VOIP (SIP, H.323)
LIDO
56
Internet Pace
years to reach 50 million users worldwide
80
74
70
60
50
38
40
years
30
20
16
13
10
4
0
telephone
LIDO
radio
PC
TV
WWW
57
A Brief History of the Internet
• 1969
• 1970’s
• 1973
• 1980
• 1983
• 1990
• 1995
LIDO
ARPANET, the world’s first operational
packet-switched network, was created
ARPA renamed DARPA
Need for internetworking protocol
recognized, leading to the development of
TCP/IP
TCP/IP implemented on an experimental basis
TCP/IP required to participate on the
Internet
ARPANET officially dissolved
Internet commercialized
58
The Internet and Regulation
• Originally, the Internet had no regulation, no
monopoly, and no universal service mandate.
• The lack of regulation brings up many interesting
questions.
• While it is a wonderful topic of discussion, there are
no concrete answers yet.
• The Cato Institute, www.cato.org/tech offers many
papers and studies on the regulatory issues
surrounding the Internet.
LIDO
59
The Internet Society (ISOC)
• The Internet Society is a nonprofit,
nongovernmental, international organization that
focuses on Internet standards, education, and
policy issues.
– Board of Trustees (BOT)
– Internet Architecture Board (IAB)
– Internet Engineering Task Force (IETF)
– Internet Research Task Force (IRTF)
– Internet Engineering Steering Group
– Internet Research Steering Group
LIDO
60
IANA and ICANN
• The Internet Assigned Numbers Authority (IANA)
oversees IP address allocation, the Domain Name
System (DNS), root zone management, and other
numerical assignments, such as protocol and port
numbers.
• IANA is currently operated by the Internet
Corporation for Assigned Names and Numbers
(ICANN) under a contract with the U.S. Department
of Commerce, which also provides ongoing
oversight function.
LIDO
61
Number Resource Organization (NRO)
• The registration of IP addresses around the world is delegated to
five Regional Internet Registries (RIRs)
– American Registry for Internet Numbers (ARIN)
• North America
– Asia-Pacific Network Information Centre (APNIC)
• Asia-Pacific region
– Reseaux IP European Network Coordination Center (RIPE NCC)
• Europe, Central Asia, and the Middle East
– Latin American and Caribbean Internet Addresses Registry
(LACNIC)
• Latin America and the Caribbean
– African Network Information Centre (AfrNIC)
62
LIDO
• Africa
NRO, RIR, IANA and ICANN
• IP addresses, both IPv4 and IPv6, as well as
autonomous system (AS) numbers are managed and
sold by the RIRs, each operating in different regions of
the world.
• IANA delegates large groups of IP addresses to the
various RIRs, which then reallocate smaller groups of
addresses in their regions to ISPs and other
organizations.
• The NRO has entered into an agreement with ICANN
to establish an organization, referred to as the Address
Supporting Organization (ASO) to deal with the
coordination of global IP addressing policies within the
63
LIDO ICANN framework.
Basic IP Routing
Computer
Routing
Table
Router
Router
Virtual
Circuit
(VC)
Virtual Circuit
(VC)
LAN
Router
Input
Ports
Routing
Table
Output
Ports
Routers examine the
destination address in
the IP header, check
the destination against
Packets queued up
a routing table, compute
Packets can be
for subsequent
the next hop, and send
lost due to congestion.
transmission.
packet to next hop.
Introduces latency Causes packet loss
LIDO
TCP requests
retransmission
UDP does not
64
Transmission Control Protocol (TCP)
Layer 7
APPLICATION
Network applications present data to TCP.
Layer 6
PRESENTATION
Layer 5
SESSION
TCP is responsible for virtual circuit setup,
acknowledgements, flow control, and
retransmission of lost or damaged data.
Layer 4
TRANSPORT
Layer 3
NETWORK
Layer 2
DATA LINK
Layer 1
LIDO
PHYSICAL
TCP breaks the data into pieces,
numbering each piece so that receipt can be
verified and the data can be put back in the
proper order. Provides end-to-end
connection-oriented, reliable virtual circuit
service.
TCP uses a system of port numbers to ensure
That data reaches the right application. Port numbers
range from 1 to 65,535. Used by firewalls and IP
addresses to control the flow of information. 65
User Data Protocol (UDP)
Layer 7
APPLICATION
Layer 6
PRESENTATION
Layer 5
SESSION
UDP provides end-to-end connectionless,
unreliable datagram service.
TRANSPORT
UDP does provide provide for error
correction or sequenced packet delivery
Layer 3
NETWORK
UDP does not request retransmissions,
minimizing delay, but often reducing quality
Layer 2
DATA LINK
Layer 1
PHYSICAL
Layer 4
LIDO
URP is well suited for query response
applications. It is also used for
multicasting, VoIP, streaming media
and multimedia applications.
66
Stream Control Transport Protocol
(SCTP)
Layer 7
APPLICATION
Layer 6
PRESENTATION
Layer 5
SESSION
Layer 4
TRANSPORT
SCTP , a layer 4 protocol, is designed to
overcome the limitations of TCP with respect
to the transport of signaling messages and VoIP
network.
Originally intended for the transport of telephony
Signaling protocols over IP.
Supports multistreaming and multihoming.
Layer 3
Layer 2
Layer 1
LIDO
NETWORK
DATA LINK
PHYSICAL
SCTP can apply per-stream, in-order delivery to the
destination application.
Other applications benefiting from SCTP include
multimedia Web browsing, video over IP, and IPTV.
67
Datagram Congestion Control Protocol
(DCCP)
Layer 7
APPLICATION
Layer 6
PRESENTATION
Layer 5
SESSION
Layer 4
TRANSPORT
Layer 3
NETWORK
Layer 2
DATA LINK
Layer 1
PHYSICAL
LIDO
DCCP , layer 4 protocol, designed to address
the growing range of voice, video and multimedia
application being introduced on the Internet
and IP networks.
DCCP provides congestion
control for unreliable data flows.
Features include unreliable transport with
Acknowledgements, realiable handshake
and negotiation of the features, and support
for TCP-like or TCP-friendly rate control for
congestion control.
68
Internet Control Message Protocol
(ICMP)
Layer 7
APPLICATION
Layer 6
PRESENTATION
Layer 5
SESSION
Layer 4
TRANSPORT
Layer 3
NETWORK
Layer 2
DATA LINK
Layer 1
PHYSICAL
LIDO
ICMP provides error handling and control
functions. It is a required protocol tightly
integrated with IP.
ICMP messages, delivered in IP packets, are
used for out-of-band messages related to
network operation or mis-operation.
ICMP functions include announcing network
error, announcing network congestion,
assisting in troubleshooting, and announcing
timeouts.
Since ICMP uses IP, ICMP packet delivery
is unreliable.
69
Internet Group Management Protocol
(IGMP)
Layer 7
APPLICATION
Layer 6
PRESENTATION
Layer 5
SESSION
Layer 4
TRANSPORT
Layer 3
NETWORK
Layer 2
DATA LINK
Layer 1
PHYSICAL
LIDO
IGMP allows Internet hosts to participate in
multicasting.
This standard describes the basics of
multicasting IP traffic, including the format of
multicast IP addresses, multicast Ethernet
encapsulation, and the concept of a host group.
A host group is the set of hosts interested in
traffic for a particular multicast address.
IGMP allows a router to determine which host
groups have members on a given network
segment.
IGMP does not address the exchange of
multicast packets between routers.
70
ARP/RARP
Layer 7
APPLICATION
Layer 6
PRESENTATION
Layer 5
SESSION
Layer 4
TRANSPORT
Layer 3
NETWORK
Layer 2
DATA LINK
Layer 1
PHYSICAL
LIDO
Address Resolution Protocol (ARP)
determines the physical address of a node.
ARP is the mapping link between IP
addresses and the underlying physical
address, or Media Access Control (MAC)
address.
Reverse Address Resolution Protocol
(RARP) enables a host to discover its own IP
address by broadcasting its physical address.
71
IP Routing
LIDO
• Routing protocols allow routers to communicate
with each other
• Routers create a routing table
• Forward packets hop-by-hop to the destination
• Routers examine destination address in IP header
• Select the most efficient path to the destination
based on longest/best prefix match comparison
between destination address in the packet and the
IP router’s forwarding table
• Dynamic, scalable and robust
72
Role of Gateway Protocols
AS25367
AS45689
IGP
IGP
IGP
EGP
IGP
LIDO
IGP
IGP
73
Role of Gateway Protocols
• Gateway protocols are used within and between
Autonomous Systems (AS).
– The autonomous system number is a unique number that
essentially identifies a portion of the Internet
– Autonomous system numbers are managed and assigned
by the Regional Internet Registries (RIRs)
• Interior Gateway Protocol (IGP)
– Interior or intra-domain routing protocol inside AS
– Key protocols used today include OSPF and IS-IS
• External Gateway Protocol (EGP)
LIDO
– Exterior or inter-domain routing protocol between ASs
– Key protocol used today is BGP4
74
Routing Protocol Algorithms
Distance Vector
• Routing protocol that requires that each router simply inform
its neighbors of its routing table.
• Routers periodically flood table of vectors
• Other routers receive table, add their local costs and
calculate forwarding table
• For each network path, the receiving routers pick the
neighbor advertising the lowest cost, then add this entry into
its routing table for re-advertisement.
• Router tells ONLY it’s neighbors about ALL routes
• Examples include IP, RIP (Routing Information Protocol),
Novell IPX RIP, AppleTalk Routing Table Management
Protocol (RTMP), and Cisco Interior Gateway Routing
Protocol (IGRP).
LIDO
75
Routing Protocol Algorithms
Link State
• This type of routing protocol requires each router to
maintain at least a partial map of the network.
• When a network link changes state, a notification is
flooded throughout the network. All the routers note
the change, and recompute their routes accordingly.
• More reliable, easier to debug and less bandwidthintensive than Distance-Vector, but it is more
complex and more compute- and memoryintensive.
• Examples include OSPF, IS-IS and NLSP.
LIDO
76
Interior Gateway Protocols - OSPF
• Open Shortest Path First (OSPF) is the most
widely used interior routing protocol in large
networks.
• It is a link-state protocol, using Dijkstra’s
algorithm.
• Determines routes based on path length,
calculates the shortest-path tree, and uses
cost as its routing metric.
LIDO
77
Interior Gateway Protocols - OSPF
• An OSPF network is divided into areas.
– Backbone Area
– Stub Area (SA)
– Totally Stubby Area (TSA)
– Not-So-Stubby Area (NSSA)
LIDO
78
Interior Gateway Protocols - OSPF
• OSPF defines several types of routers.
– Area Border Router (ABR)
– Autonomous System Boundary Router (ASBR)
– Internal Router (IR)
– Backbone Router (BR)
– Designated Router (DR)
• Looks like a star topology with many areas all
attached to the backbone area.
LIDO
79
Interior Gateway Protocols - OSPF
• The basic building block of the OSPF routing
protocol for IP is the link-state advertisement
(LSA).
• LSAs provide a description of a router’s local
routing topology that is distributed to all other
routers.
• OSPF is designed to be scalable.
– LSAs are sent only to interfaces that belong to the
appropriate area.
• Makes use of both unicast and multicast.
LIDO
80
OSPF Update
• Updates have been added to OSFP under the
auspices of the IETF OSPF Working Group
• Some current working areas include
– RFC 2470 OSPFv3 for IPv6
– RFC 2370 Opaque LSA (link state
advertisement)
– Non-stop forwarding (NSF)
– Multiple address families
– Traffic Engineering, DiffServ and Optical
extensions
LIDO
81
Interior Gateway Protocols – IS-IS
• Intermediate System-to-Intermediate System (IS-IS)
was developed by the ITU around the same time as
the IETF was developing OSPF.
• Another routing protocol used to determine the best
way to forward packets through the network.
• It is a link-state protocol and uses Dijkstra’s
algorithm.
• Unlike OSPF, IS-IS does not use IP to carry the
routing information messages.
LIDO
82
Interior Gateway Protocols – IS-IS
• It also differs from OSPF in how it defines its routers
and areas.
– Level 1 router is intra-area
– Level 2 router is inter-area
– Level 1-2 router covers both
• Where OSPF networks look like star topology, IS-IS
networks look like a central spine of Level 2 routers
with branches of Level 1-2 and Level 1 routers
forming the individual areas or networks.
LIDO
83
IS-IS Update
• Updates have been added IS-IS under the
auspices of the IETF IS-IS Working Group.
• Some current working areas include
– IS-IS for IPv6
– Restart Signaling (NSF)
– Multi-Topology Routing
– Traffic Engineering, DiffServ and Optical
Extensions
LIDO
84
Exterior Gateway Protocols (EGP)
• Occurs between Autonomous Systems (AS) and is
of concern to service providers and other large or
complex networks.
• There is a single EGP to manage the global Internet
and very large private IP networks.
• It is based on Border Gateway Protocol version 4
(BPG4).
• Routers determine the path for a data packet by
calculating the number of hops between
internetwork segments.
LIDO
85
Exterior Gateway Protocols (EGP)
• Uses a path-vector protocol where routing decisions
are based on network policies or rules rather than
technical parameters as in the case of distancevector and link-state protocols.
• Used by most ISPs to enable routing with each
other.
• Considered one of the most important protocols of
the Internet.
LIDO
86
BGP Update
• BGP is being updated to support new extensions,
under the auspices of the IETF Inter-domain Routing
Working Group
• Some current working areas include
– Multi-Protocol BGP (MP-BGP), RFC 2858
– Graceful Restart (GR)
– L2VPN and L3VPN Auto-Discovery; VPLS
signaling
– BGP Tunnel Encapsulation Signaling
– soBGP (secure origin BGP); s-BGP (secure BGP)
LIDO
87
Why TCP/IP ?
Many IP Routing Protocols
AS45208
IGP/BGP
AS34628
IGP/BGP
IGP/BGP
IGP/BGP
IGP/BGP
IGP/BGP
IGP/BGP
IGP/BGP
IGP/BGP
BGP4
IGP/BGP
LIDO
88
Why TCP/IP ?
Many Transport Protocols
Transport Layer
TCP, UDP, SCTP, DCCP
Network Layer
IP
Data Link Layer
LIDO
89
Why TCP/IP ?
Many Link Layers
Network Layer
Layer
Transport
TCP, UDP, SCTP, DCCP
Network Layer
IP
Data Link Layer
Wireless Satellite
LIDO
Ethernet
IP/MPLS
ATM
Optical
90
ISP Network
Architecture
POP
Edge Routers
Intra-POP
Network
Core
Routers
Access Lines
POP
Subscribers
IP Backbone
Edge Routers
Intra-POP
Network
Access Lines
Subscribers
LIDO
91
Internet Composition
Backbone
Provider
ISP
Backbone
Provider
EP
ISP
ISP
ISP
Subscriber
ISP
Subscriber
LIDO
ISP
Cable ISP
= Exchange Point
S
S
S
Dial
ISP
DSL
ISP
S
92
ISP Peering Architecture
ISP-X
X
ISP-Z
X
X
Z
X
Z
Z
X = Routes for ISP X Customers
LIDO
Z
Z = Routes for ISP Z Customers
93
Internet Transit
Architecture
Global
Internet
X
Higher Tier ISP
Routes to
Internet
X
Local ISP X
X = Routes for ISP-X Customers
LIDO
C
C
C
C
= ISP-X Customer
94
Internet Addressing
LIDO
• A globally accepted method of identifying
computers was needed.
• IP acts as the formal addressing mechanism for all
Internet messaging.
• Each host on the Internet is assigned a unique 32bit Internet address, the IP address, which is placed
in the IP header and used to route packets to their
destination.
• IP addresses are assigned on a per-interface basis,
so a host can have several IP addresses if it has
several interfaces.
95
Internet Addressing and
Information Flow
• Three approaches to information flow
between two or more points on the Internet or
IP networks.
– Unicast
– Multicast
– Anycast
LIDO
96
Unicast
V1
V2
V3
Router
V1
V3 V2
V = Viewers
Server
V1
V2
Router
V3
– Information sent from one transmitter to one receiver
– Stream goes to single user at a time
– Each destination address identifies a single user
LIDO
V1
V2
Router
V3
97
Multicast
V
Multicast
Router
V = Viewers
V
Server
MRouter
V
– Information sent from one transmitter to multiple receivers
]
– Stream goes to multiple users at a time
MRouter
– Each destination address identifies a group of receivers
LIDO
V
V
V
98
IP Anycast
Client 1
NETWORK
Router 3
Router 5
Router 1
Router 2
Server
“A”
Router 6
Client 2
Router 4
Router 7
Server
“A”
LIDO
Server
“A”
Client 3
99
Internet Addressing
• IP addresses, both IPv4 and IPv6, as well as
autonomous system (AS) numbers are managed
and sold by several organizations, each operating
in different geographies
LIDO
– American Registry for Internet Numbers (ARIN)
• North America
– Asia-Pacific Network Information Centre (APNIC)
• Asia-Pacific region
– Reseaux IP European Network Coordination Center
(RIPE NCC)
– Latin American and Caribbean Internet Addresses
Registry (LACNIC)
– African Network Information Centre (AfrNIC)
100
Internet Addressing
• Each physical network has its own unique network
address.
• Each host has its own unique address.
• Routers or gateways have one or more addresses.
• A basic concept of IP addressing is that initial
prefixes of the IP address can be used for
generalized routing decision.
• Once a packet reaches its target network, its host
field is examined for final delivery.
LIDO
101
IPv4 32-bit Addressing
Class A
1.0.0.0-126.0.0.0
126
16,777,214
Class B
128.0.0.0-191.255.0.0
16,384
65,534
Class C
192.0.0.0-223.255.255.0
Class D
multicast
224.0.0.0-239.0.0.0
2,097,152
254
Class E
reserved
240.0.0.0-247.0.0.0
LIDO
102
IPv4 Class A Address
Internet Protocol (IP)
Address
124 . 29 . 88 . 7
Network ID
LIDO
Host ID
103
IPv4 Class B Address
Internet Protocol (IP)
Address
130 . 29 . 88 . 7
Network ID
LIDO
Host ID
104
Classless Interdomain Routing
(CIDR)
• The "classful" system of allocating IP addresses
can be very wasteful.
• In the early 1990s, the IETF began implementing
Classless Interdomain Routing (CIDR).
• Networks can be broken down into subnetworks,
and networks can be combined into supernetworks,
as long as they share a common network prefix.
• A CIDR address is still a 32-bit IP address, but it is
hierarchical rather than class based.
LIDO
105
Classless Interdomain Routing
(CIDR)
• Basically, a route is no longer an IP address,
broken down into network and host bits according
to its class. A route is now a combination of
address and mask.
• The mask indicates how many bits in the address
represent the network prefix.
• For example, the address 200.200.14.20/23 means
that the first 23 bits of the binary form of this
address represent the network. The bits remaining
represent the host.
• In decimal form, the prefix 23 would correspond to
106
the subnet mask 255.255.254.0.
LIDO
CIDR Masking Scheme Examples
LIDO
Mask as Dotted Mask as Prefix
Decimal Value
Value
255.255.255.224 /27
Number of Hosts
255.255.255.0
/24
256
255.255.224.0
/18
16,384
255.255.0.0
/16
65,536
255.248.0.0
/13
524,288
32
107
Subnetting
LIDO
• Subnetting allows you to create multiple logical
networks that exist within a single network.
• Subnetting allows single routing entries to refer
either to the larger block or to its individual
constituents.
• This permits a single, general routing entry to be
used through most of the Internet, more specific
routes only being required for routers in the
subnetted block.
• Allows division of host space into M number of
subnets, each with H number of hosts.
108
Subnet Mask
• Applying a subnet mask to an address allows you to
identify the network and node sections of an IP
address
• A subnet mask is another 32-bit binary number,
which acts like a filter when it is applied to the 32-bit
IP address.
• Class A, B, C and D addresses have a self encoded
or default subnet mask built in.
LIDO
–
–
–
–
Class A - 255.0.0.0
Class B - 255.255.0.0
Class C - 255.255.255.0
Class D – 255.255.255.255
109
Key Internet Addresses
• IP Address
– For example 152.107.102.7
• Subnet Mask
– For example, 255.255.0.0
• Default Gateway
– For example, 152.107.102.1
LIDO
110
Network Address Translation
• Network Address Translation (NAT) is another
technique used to deal with the shortage of IPv4
addresses.
• Enables a LAN to use one set of IP addresses for
internal traffic and a second set of addresses for
external traffic.
• The NAT function in the router performs the
address translations between the public and private
IP addresses.
LIDO
111
Network Address Translation
• NAT-enabled routers do not have end-to-end
connectivity, therefore they cannot take part
in some of the Internet protocols.
• Two main types of NAT – dynamic and static.
• NAT serves to make end-to-end performance
very difficult.
LIDO
112
IPv6 Addressing
• Researchers predict that we will run out of IPv4
addresses by 2009.
• IPv6 will provide 128 bit addressing, or 3.4 x 1038th
total addresses
– 340 undecillion (billion, billion, billion, billion) unique
addresses
• Addressing structure uses hexadecimal notation,
written as eight groups of four hexadecimal digits,
and colons replace the periods used in IPv4
– For example 2001:0db8:85a3:0000:1319:8a2e:0370:7344
LIDO
113
IPv6 Addressing
• IPv6 involves four address types
–
–
–
–
Unicast
Anycast
Multicast
Reserved class
• It is a natural increment to IPv4, and can be
installed as a normal software upgrade in internet
devices and is interoperable with the current IPv4.
• IPv6 is designed to run well on high performance
networks (e.g. Gigabit Ethernet, OC-12, ATM, etc.)
and at the same time still be efficient for low
114
bandwidth networks (e.g. wireless).
LIDO
IPv6
• IPv6 benefits include
– Improved routing efficiency
– Simplified administration
– Improved quality of service capabilities
– Provides improved security mechanisms
LIDO
115
IPv4-to-IPv6 Translation
IPv4 Network
IPv4 Hosts & Devices
LIDO
IPv4
Packets
IPv6
Packets
IPv6 Network
NAT-PT
Performs protocol translation and
network address translation
IPv6 Hosts & Devices
116
IPv4-to-IPv6
Dual Stack
IPv4
IPv6
Applications Applications
Sockets API
UDP/TCP v4
UDP/TCP v6
IPv4
IPv6
L2
IPv6
IPv6
IPv4
A A to B B B to C C
IPv6
IPv4
IPv4
IPv6
IPv6
D D to EE E to F F
IPv4
IPv6
A general property of a dual-stack node
is that an IPv6 socket can communicate both
with an IPv4 and IPv6 peer at the transport
layer (TCP or UDP).
L1
LIDO
All the internal plumbing and conversion
of address types is done by the dual-protocol
stack.
117
IPv4-to-IPv6 6to4 Tunneling
IPv6 Host Address
2002:C80F:F01:100::1
IPv6 address
2002:C80B:B01::/48
IPv4 address
200.15.15.1
IPv6 Site 1
IPv6 Site 1 address
2002:C80F:F01::/48
Embedded IPv4 address
(V4ADDR) for Site 1
C80F:F01=200.15.15.1
LIDO
Embedded IPv4 address
(V4ADDR) for Site 2
C80B:B01=200.11.11.1
IPv4 Backbone
6to4 Router 1
6to4 Router
IPv4
IPv6
Header Header
IPv6 Site 2
IPv6 Host B
2002:C80B:B01:100::1
When Host A sends traffic to Host B (destination 2002:C80B:B01:100::1),
it is routed via the 6to4 Router1. This router has a 6to4 tunnel configured,
with a tunnel source (200.15.15.1) but no tunnel destination.
The tunnel destination is computed on-the-fly by extracting
the embedded IPV4ADDR from the destination address (2002:C80B:B01:100::1/64),
and used to encapsulate the IPv6 packet into IPv4
118
(source 200.15.15.1, destination 200.11.11.1).
IPv6 Status
• The push to IPv6 was driven at first by a concern
that the supply of available IP addresses would
soon run out, and the addressing scheme had to be
changed to allow for more addresses
• But, especially in the United States, this shortage
has not yet been realized.
• Furthermore, CIDR (Classless Inter-Domain
Routing), NAT (Network Address Translation),
NAPT(Network Address Port Translation) and
similar technologies have helped ease the strain on
IP addresses.
LIDO
119
IPv6 Status
• Fears about imminent IP address depletion have
been somewhat exaggerated.
• Therefore, IPv6 has largely (and justifiably)
"dropped off the radar screen" of U.S. enterprises,
although it has become a strategic priority in
Europe and a pressing issue in Asia.
• However, with the U.S. government’s mandate that
the Dept of Commerce deploy IPv6 by 2008,
followed by the Department of Defense in 2010,
more attention is now being focused on the
migration to IPv6.
LIDO
120
IPv6 Status
• It is believed that the mobile market will ultimately
be the greatest pusher of IPv6.
• However, there is very little end-user (i.e.,
application) demand for IPv6 at this time.
• Therefore, infrastructure providers have no
economic incentive to build out an IPv6
infrastructure.
• The primary benefits of IPv6 at this time accrue at
the network management level, in areas such as
interdomain routing, network configuration, end-toend security and address space management.
LIDO
121
The 6bone Network
• Established in 1996 by the IETF the 6bone
network was the first experimental
environment for IPv6 research.
• More than 1,173 network in over 60 countries
were connected to the 6bone IPv6 network.
• 6bone ceased to operate in June 2006.
LIDO
122
Domain Name System (DNS)
• Distributed database system operating on
the basis of a hierarchy of names
• Provides translation between mnemonic host
names and IP addresses
• Host name takes the form of
– host.domain.top-level_domain
• www.telecomessentials.com
LIDO
123
How DNS Servers Work
Local Loop
ISP POP
Web Browser
#1
Browser sends URL to
request IP address
Local
DNS Server
T/E/J-Carrier
OC levels
Transport
#2
If local IP address,local
name server returns the
address to your computer
#3
#3
Local ISP
Using the IP address
browser contacts the site
#4
Internet
Backbon
e
#4
Website
Site send info requested
LIDO
124
How DNS Servers Work
Root Servers
Local Loop
Web Browser
ISP POP
#1 Browser sends URL
T/E/J-Carrier,
OC levels transport
#2
to request IP address
Local
DNS Server
If not on local name
server, root domain
servers are contacted.
#3
The root domain server
responds with TLD name
server containing the info
#5
#6
LIDO
#7
Name server returns
the IP address to your
computer
Using the IP address
browser contacts the site
#4
Internet
Backbon
e
TLD Name
Servers
Local name server contacts
TLD which contains the primary
and secondary name server
#5
TLD server sends info
#6
#7
Site send info requested
Local
ISP
125
Webserver
Generic Top Level Domains
(gTLDs)
• Seven generic top level domains (gTLD)
– .com commercial
– .gov government
– .mil military
– .edu education
– .net network operation
– .org non-profit organizations
– .int
international treaty organizations
• Generic domains are unrestricted--this means
anyone from anywhere can register as many .com,
.net or .org domain names as they like.
LIDO
126
DNS Administration
• The DNS was initially, until 1998, administered by
IANA (Internet Assigned Number Authority), funded
by the US Government
• Since 1993, Networks Solutions Inc (NSI) was the
sole provider of direct domain-name registration
services in the open gTLDs
• Registration authority over the ccTLDs delegated to
various bodies in each country
LIDO
127
ICANN
• Internet Corporation for Assigned Names and
Numbers (ICANN), a non-profit, international
corporation, was formed in Oct 1998.
• ICANN is assuming responsibility for a set of
technical functions previously performed under U.S.
government contract by IANA and other groups.
• Specifically, ICANN coordinates the assignment of
the following identifiers that must be globally unique
for the Internet to function:
LIDO
– Internet domain names
– IP address numbers
– protocol parameter and port numbers
128
ICANN
• ICANN governs the terms and conditions of the
gTLDs with the cooperation of the gTLD registries.
• ICANN also controls the root domain, delegating
control over each TLD to a domain name registry.
• When it comes to the ccTLDs, the government of a
given country typically controls the domain registry.
• In addition, ICANN coordinates the stable operation
of the Internet's root server system.
LIDO
129
ICANN
• ICANN is also introducing competition into the
administration of the the DNS through
– a policy for the accreditation of registrars
– a Shared Registry System for the .com, .net and
.org domains
• The Accredited Registrar Directory provides a listing
of ICANN-accredited domain name registrars that
are currently taking domain name registrations
LIDO
130
Domain Name Riches
• Tuvalu is a small Pacific country of 10,600
people
• It was assigned “.tv”as its nTLD
• Auctioned to Dot.tv for US$1 million quarterly
– adjustable for inflation – with a US$ 50
million cap over 10 years. In addition, Tuvalu
holds a 20% stake in the company.
• 4 times Tuvalu’s GDP
LIDO
131
POP Architecture Today
DSU
to Internet
T-3/E-3
OC-3,OC-12,OC-48,OC-192
analog and
BRI-ISDN
users
Access
Concentrato
r
Supports Frame Relay Access
ATM Switch T-1/E-1
supports 56/64 Kbps customers
supports T-1/E-1 customers
T-3/E-3
Access
Concentrators
Distribution Router
T-1/E-1
PRI ISDN
Access Router
NMS
Ethernet
LAN
Terminal
Server
E-mail
server
Analog
Modem
Pool
Web, Security
Domain Nameand Newsgroup
servers
Server
LIDO
28.8/33.6/5
6
Kbps users
Proxy
servers
132
Internet Challenges
• Limited bandwidth
• Increasing traffic
• Greater demands on bandwidth and performance
associated with a growing population of users –
human and machine.
• Greater use of visual, multimedia and interactive
applications.
• Bottlenecks at the ISP and NSP levels, as well as at
exchange points greatly affects performance of new
technologies like Internet telephony and multimedia
applications
LIDO
133
Redefining The Internet
• Support of real-time traffic flows required
– real-time audio/video
– live media
– streaming media
– Interactivity
• Introduction of QoS into the Internet required
• Class of Service (CoS) vs Quality of Service (QoS)
– CoS is simply a prioritization scheme
– QoS address management of specific traffic
parameters
LIDO
134
Redesigning the Internet Core
• Shift from connectionless routers to connectionoriented frame relay, ATM and MPLS networks
– separating traffic types
– prioritizing time-sensitive traffic
– reducing access costs by eliminating leased line
connections
• Moving from OC-3 to OC-12 (155 Mbps to 622
Mbps) in the backbone to capacities of OC-48 (2.5
Gbps), OC-192 (10 Gbps), and even some early
deployments of OC-768 (40 Gbps).
LIDO
135
Next Generation Internet
Infrastructure
•
•
•
•
•
•
•
•
•
High-speed real-time, multimedia network
Class of Service and Quality of service guarantees
Next generation telephony
SDH/SONET, DWDM, optical networking
Use of ATM, MPLS, GMPLS networking protocols
IPv6 protocols addressing real-time traffic requirements
Increased security
Distributed networked intelligence
Multiple broadband access alternatives
– dial-up - xDSL, cable modems, DBS, MMDS, LMDS
– dedicated - T-3/E-3, OC-3/OC-12, frame relay, ATM
LIDO
136
Service Provider Characteristics
• Varying coverage areas
– Local, regional, national, or global coverage
• Varying access options
– POTS, ISDN, ADSL, frame relay, ATM, cable modems,
satellite, wireless
• Varying services
– E-mail, FTP, Webhosting, name services, Virtual Private
Networks (VPNs), VoIP services, application hosting
• Number of hops to Internet interconnection point is
an issue
• Customer service even a bigger issue
LIDO
137
Service Provider Characteristics
• Worth remembering how easy it is to become an
ISP
– Some 10,000 worldwide
• (www.thelist.com)
• That is why there is an ISP pecking order
–
–
–
–
LIDO
Research backbones have latest technology
Top tier providers focus on business class services
Lower tier providers focus on rock bottom pricing
Large variations in capacity, performance, topology,
redundancy, connections with other operators, customer
service, and price
138
Organization of the Internet
Internet 2, Abilene Project, Geant
Interplanetary Internet
Research
Backbone
GigaPops
California NAP
PacBell
Chicago NAP
Ameritech
Wash D.C. NAP
MCI Worldcom
Network
Service
Providers
SprintLink
Cable & Wireless
Uunet
AT&T
WorldNet
New York NAP
Sprint
Qwest
(NSPs)
NAPs
IXPs,EPs
MAE East
Worldcom
LINX
London
HKIX
Hong Kong
Top-tier
ISPs
Top-tier
ISPs
SIX
Sydney
KIX
Korea
Internet
Service
Providers
(ISPs)
Top-tier
ISPs
Top-tier
ISPs
Top-tier
ISPs
Lower-tier
ISPs
LIDO
139
Interconnection & Exchange Points
LIDO
• An IXP is a public meeting point where NSPs/ISPs
exchange traffic with their counterparts.
• IXPs allow NSPs and top-tier ISPs to exchange
Internet traffic without having to send the traffic
through main transit links.
• Over 200 IXPs worldwide.
• Most IXPs are for-profit.
• IXPs have become another point of congestion.
Both losses and delays negatively impact voice,
video & multimedia applications.
140
Example of one
Of the original
Network Access Points
The Pacific Bell NAP
LIDO
141
Private Peering Agreements
ISP-X
X
ISP-Z
X
X
Z
X
Z
Z
X = Routes for ISP X Customers
LIDO
Z
Z = Routes for ISP Z Customers
142
IP Quality of Service
• See “QoS in Converged Data and Voice Networks”
• QoS is of increasing importance in all networks.
• QoS deals with the strict management of traffic
such that guarantees can be made.
• In the context of packet switching networks, QoS
basically guarantees that a packet will travel
successfully between any two points.
• Internet and IP originally structured to be best effort.
• New class of applications require QoS
• As a result, much attention is being focused on
143
LIDO
developing QoS mechanisms and protocols.
IP Quality of Service
• There is a growing requirement for QoS to meet, or
in fact exceed, expectations of end-users and
applications communicating over a packet network.
• Three main options exist to fulfilling this
requirement
– Over-provisioning
– Traffic engineering
– Fancy queuing
• This requires QoS mechanisms
LIDO
144
QoS Mechanisms
Queue Management
Example: RED
Queue Scheduling
Ex: FQ, WFQ, WRR, DRR
Classification and
Conditioning
Edge
Device
Router
LIDO
145
Queue Management
• Random Early Detection (RED)
– The main approach to queue management
– RED monitors time-based average queue length
(AvgLen) and drops arriving packets with
increasing probability as AvgLen increases
– No action is taken if the AvgLen < MinTH and all
packets are dropped if AvgLen > MaxTH.
LIDO
146
Queue Scheduling - FQ
Source
1
Edge
Device
Queue 1
1
Queue 2
Source
2
2
Queue 3
Source
3
LIDO
Classifier
3
Scheduler
147
Queue Scheduling - WFQ
Source
1
Edge
Device
Queue 1 – 50%
1
Queue 2 – 33%
Source
2
Source
3
LIDO
2
Classifier
Queue 3 – 17%
3
Scheduler
148
Queue Scheduling - WRR
Queue 1 – Priority 1
Source
1
Edge
Device
Queue 2 – Priority 2
W2
Source
2
Source
3
LIDO
W1
Classifier
Queue 3 – Priority 3 W3
Scheduler
149
Queue Scheduling - DRR
Source
1
Queue #1
Edge
Device
1500B
Source
2
LIDO
Queue #2
800B
Classifier
Source
3
-Assign Quantum to Queue Scheduler
-Initialize deficit counter to 0
-If packet size <= quantum + deficit counter,
allow packet to pass, update deficit counter
-If packet size > quantum, add quantum to
deficit counter, wait for next pass
1200B
Queue #3
Scheduler
Quantum = 1000
150
IP QoS Continuum
Cost
IntServ
DiffServ
Best-Effort
LIDO
Complexity
151
Differentiated Services Architecture
Interior Routers
Ingress edge routers
Interior (core) routers
Egress edge routers
classify, mark and police
enforce the appropriate Shape flow aggregates
flow aggregates
Per Hop Behavior (PHB)
DiffServ is a prioritization model with preferential
allocation of resources based on traffic classification
LIDO
152
Differentiated Services (DiffServ)
• There are several defined DiffServ Per-HopBehaviors
– Default, which provides for best effort
– Expedited Forwarding (EF), specified under RFC
2598
– Assured Forwarding (AF), and is specified under
RFC 2597
– Class Selectors
LIDO
153
IntServ and RSVP
Edge
Router
Application
Host
A
Core
Router
Edge
Router
PATH
PATH
RESV
RESV
User
B
1. Applications must know the characteristics of their traffic before hand and signal
the intermediate network elements to reserve the resources to meet its traffic properties.
2. The application sends a special data packet (PATH message), to the receiver in order to
reserve network resources. The packet contains the characteristics of the traffic to be sent.
3. If the resources are available, the network reserves them and sends back a positive
acknowledgement (the RESV message), reserving the path from source to destination.
4. If the resources are not available, the network returns a PATH Error message.
5. The positive or negative acknowledgements are the “Admissions Control” aspect of the
IntServ standard.
LIDO
154
Resource Reservation Protocol
• RSVP is a resource reservation setup protocol for
the Internet.
• Its major features include
– The use of ``soft state'' in the routers
– Receiver-controlled reservation requests
– Flexible control over sharing of reservations and
forwarding of subflows
– And the use of IP multicast for data distribution.
• RSVP on the public Internet is impractical,
presenting a big scalability problem.
LIDO
155
RSVP
• RSVP signaling has evolved into a general purpose
signaling protocol for IP-based networks,
applications and services.
– Classic RSVP (RFC 2205)
– MPLS Traffic Engineering - RSVP-TE, RFC 3209,
specifies “Extensions to RSVP for LSP Tunnels”
– RSVP-TE Extensions for GMPLS, RFC 3473
– RSVP-TE extensions for fast restoration, including IETF
draft “Crankback Signaling Extensions for MPLS
Signaling”.
LIDO
156
Next Generation Internet (NGi)
• The Next Generation internet (NGi) will be so
pervasive, reliable and transparent that we'll all just
take it for granted. It will be a seamless part of life-like electricity or plumbing.
• Some NGi projects underway inlcude
–
–
–
–
–
Internet2
Abilene
HOPI (Hybrid Optical Packet Infrastructure)
NLR (National LambdaRail)
MAN LAN (Manhattan Landing Exchange Point),
GÉANT2 (GN2)
– TEIN2
LIDO
157
LIDO
158
LIDO
159
Internet Enabled Devices
LIDO
160
Radio Frequency Identification
(RFID)
RFID
Tag
]]]]]]
Antenna
Reader
Computer
System
LIDO
161
Radio Frequency Identification
(RFID)
• The “Internet of Things“ – enabled by RFID
and sensor technologies.
• Today we are quickly moving into a new era
of ubiquity, where the 'users' of the Internet
will be counted in the billions and where
humans may become the minority as creators
and receivers of information.
LIDO
162
Radio Frequency Identification
(RFID)
• Internet of Things is not about tagging dumb
objects, its about making things smarter, doing
more than they were originally intended to.
• The potential benefits are great, but there could
also be negative impacts.
• Additionally, privacy concerns are huge, so privacy
and protection should become part of the design
itself of the technology, even before it makes it to
market.
LIDO
163
SIP Telephony
• The concepts behind Session Initiation
Protocol (SIP) promise to be disruptive.
• SIP represents something much more
dramatic than VoIP, addressing much more
than telephony.
• SIP means all sorts of applications that open
doors of capabilities that weren’t possible in
the TDM world.
LIDO
164
Digital Objects and Libraries
• Structured information – data surrounded by a layer
of software.
• Uninterpreted strings as “handles”
• Binding of object & controls in indexed repositories
• Digital signatures for authenticity & integrity
protection
• Codification of copyright control, terms and
conditions
• Long-term storage - 100s of years
• Storage Media Challenges
LIDO
165
What’s Next ?
Web 2.0
• Web 2.0 defines the second generation of
services on the Web.
• Includes the notion of the web as a
programming platform.
• Emphasis on the harnessing of collective
intelligence.
• Involves enriched data, including enhanced
graphics, visualization and multimedia.
• Traditional media is the enemy of Web 2.0.
LIDO
166
What’s Next ?
Web 2.0
• Shift in nature and form of content.
• Text is no longer simply data
• Radio is not the only source of audio, new
options include downloading, streaming or
podcasting.
• TV programs no longer married to TV
networks.
• Web 2.0 = digital democracy practiced by
digital utopians.
LIDO
167
What’s Next ?
The Semantic Web
• Sir Tim Berners-Lee’s latest project
• Refined indexing and searching
• Enhanced processing of structured
information
• Command and control of scientific
instruments; labeling of data
LIDO
168
LIDO Telecommunications Essentials®
The Internet and IP Infrastructures
Lili Goleniewski
The LIDO Organization, Inc.
www. telecomessentials.com
+1-415-457-1800
[email protected]
Skypes ID: lili.goleniewski
Telecom Essentials Learning Center
www.telecomessentials.com
LIDO
Copyright © 2007- The LIDO Organization, Inc.
All Rights Reserved
169