Review of Networking Technologies
Download
1 / 53

Review of Networking Technologies - PowerPoint PPT Presentation


  • 217 Views
  • Updated On :

Review of Networking Technologies Vahid Tabatabaee Fall 2007. References. Title: Internetworking with TCP/IP vol. I Principles, Protocols, and Architecture Author: Douglas E. Comer Publisher: Prentice-Hall

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Review of Networking Technologies' - ismet


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Slide1 l.jpg

Review of Networking Technologies

Vahid Tabatabaee

Fall 2007


References l.jpg
References

  • Title: Internetworking with TCP/IP vol. I Principles, Protocols, and Architecture

    Author: Douglas E. Comer

    Publisher: Prentice-Hall

  • Title: Network Processors Architectures, Protocols, and PlatformsAuthor: Panos C. LekkasPublisher: McGraw-Hill

  • Title Computer Networking: A Top-Down Approach

    Author: J.F. Kurose, K.W. Ross

    Publisher: Addison Wesley


Connection oriented communication l.jpg
Connection Oriented Communication

  • Connection oriented communication forms a dedicated connection (circuit, path) between two points.

  • E.g. Telephone systems, ATM, Frame Relay

  • Potential Advantages:

    • Easier to make it reliable (note it is not necessarily more reliable).

    • Guaranteed/reserved bandwidth.

    • Identify flows by connection identifier rather than source/destination address (tag switching)


Connection less communication l.jpg
Connection-less Communication

  • Data is segmented into packets.

  • Every packet has identification information that enables network hardware to send it to the specified destination.

  • E.g. Ethernet, Internet Protocol

  • Potential Advantages:

    • More efficient use of resources


Network hierarchy 3 layer l.jpg
Network Hierarchy (3 layer)

  • Enterprise Network

    • Typical networks in companies, universities.

    • Based on Ethernet, Fast-Ethernet, WiFi.

    • Contains one or more LAN connecting PC, printers, servers

    • They can also have faster connections based on Gigabit Ethernet to connect to server and storage subsystems.

    • Gateway and customer access routers provide connection to the rest of the world

  • Access Network (provider network)

    • Aggregate customer traffic.

    • Send the aggregated traffic through a larger pipe into the WAN.

    • We have three kind of routers here:

      • Provider Edge Router (infamous last mile connection)

      • Provider core router

    • The typical speed range OC-3 and OC-48

  • WAN

    • Interconnect provide or career networks

    • The typical speed ranges between OC-12 and OC-192



Lan man wan l.jpg
LAN/MAN/WAN

Source:

http://www.crema.unimi.it/didattica/Labsistemi/matagg/Tutorial%20Networking.htm


Slide8 l.jpg
MAN

  • MAN are large network spanning a campus or city.

  • MAN (WAN) is generally less than (over) 30-50 Km.

  • WAN spans central office facilities, while a MAN starts and ends in a central office

Source:

http://www.dbguide.net/know/know103001.jsp?mode=view&pg=1&idx=1038


4 layer network hierarchy l.jpg
4 layer Network Hierarchy

  • Core Router Requirements:

    • OC-192 wire-speed IP routing and MPLS

    • VPN

    • Traffic Engineering

  • Edge Router Requirements:

    • Aggregate multiple access network interfaces

    • Access network uplinks can be GigE OC-12

    • Reliability

      • Redundant component

      • Hot pluggable line cards

    • Multiservice Providing Platform (MSSP)

      • TDM OC-3 to OC-192

      • GigE, 10GigE LAN, 10GigE WAN

      • SAN (Fibre Channel, …)

      • IP services


Sprint logical topology l.jpg
Sprint Logical Topology

  • 18 IP routers with 36 bidirectional logical links

Source: A. Nucci, A. Sridharan, N. Taft, “The Problem of Synthetically Generating IP Traffic Matrices: Initial Recommendations”, ACM Computer Communication Review, vol. 35, no. 3, pp. 19-32 ,July 2005.


Sprint wdm technology l.jpg
Sprint WDM Technology

  • 36 OXC with 55 WDM fibers..

  • Wa = 40 OC-192 channels, Wb = 40 OC-48 channels, Wc = 40 OC-12 channels

Source: A. Nucci, A. Sridharan, N. Taft, “The Problem of Synthetically Generating IP Traffic Matrices: Initial Recommendations”, ACM Computer Communication Review, vol. 35, no. 3, pp. 19-32 ,July 2005.


Ethernet technology l.jpg
Ethernet Technology

  • Ethernet is the most popular LAN technology:

    • Shared media

    • Carrier Sense Multiple Access/ Collision Detection (CSMA/CD)

  • There are different variants of the Ethernet technology:

    • Coaxial

    • Thin wire

    • Twisted Pair (10Base-T)


10base t l.jpg
10Base-T

  • Data rate : 10Mbps

  • Broadcast, bus technology

  • Best effort delivery: Hardware provide no information to the sender that the packet is delivered

Source:

http://www.webclasses.net/Courses/Intro/6.1/demo/units/unit02/sec04b.html

  • Max. Segment length: 100m

    • Repeaters relay electrical from one cable to another. At most two bridges between any two machines.

    • Bridges learn addresses and replicate the signal if needed. They isolate Ethernet segments from each other.


Collision detection and recovery l.jpg
Collision Detection and Recovery

  • It is possible that two transmitters send data simultaneously and collision happens.

  • Each transceiver monitors the cable to see if there is a coliision.

  • When it detects collision it aborts transmission and remain idle before trying again.

  • They use a binary exponential back-off policy.


Ethernet hardware address l.jpg
Ethernet Hardware Address

  • Ethernet defines a 48-bit addressing scheme.

  • Each hardware card has a unique address assigned to it.

  • Ethernet addresses are sometimes called hardware or physical addresses.

  • Interface card receives all packets, but only send to the host that are addressed to it.

  • Three types of address:

    • Physical address of one network interface.

    • The network broadcast address (all 1s)

    • Multicast address: some interfaces can be programmed to recognize multicast addresses.


Ethernet frame format l.jpg

10101011

Alternating 0 and 1

Ethernet Frame Format

  • Ethernet frame size are between 64 and 1518 bytes (including header, data, and CRC).

  • There is also 12 byte gap between Ethernet frames.


1 gige and 10 gige l.jpg
1 GigE and 10 GigE

  • It preserves compatibility with legacy software applications developed for running on 10BaseT.

  • The technology has been proposed both for LAN and MAN/WAN.

  • The jumbo frames can be up to 9000 bytes data.

  • 10 GigE is not based on the CSMA/CD technology anymore.


Internet architecture l.jpg
Internet Architecture

  • Networks are connected by routers

  • Routers need to know about the topology of the internet beyond the networks to which they connect.

  • Routers use the destination network, not the destination host, when routing a packet.


Questions l.jpg
Questions

  • What is the exact form of Internet Addresses?

  • How Internet addresses are mapped to the Hardware addresses such as Ethernet addresses?


Host universal identifiers l.jpg
Host Universal Identifiers

  • Host Identifiers are:

    • Names: specify what an object is.

    • Addresses: Where it is.

    • Routes: How to get there.


Classes of ip addresses l.jpg
Classes of IP Addresses

  • Each host has a unique 32 bit internet address.

  • Each address is a pair of (netid, hostid).

0.0.0.0 --127.255.255.255

128.0.0.0 --191.255.255.255

192.0.0.0 --223.255.255.255

224.0.0.0 --239.255.255.255

240.0.0.0 --255.255.255.255

  • 127.0.0.1 is the loopback address in IP. (127.0.0.0 to 127.255.255.255)

  • 0.0.0.0 – 0.255.255.255 (zero addresses should not be used).

  • 255.255.255.255 broadcast to all other nodes on the LAN

  • In general zeros mean this and ones mean all.


Classless inter domain routing l.jpg
Classless Inter-Domain Routing

  • It replaces the older system based on classes

  • Most sites were too big for class C and received class B number.

  • Depletion of class B addresses (~16,000 total)

  • It looks like a normal IP address but it ends with a slash and a number following it.

  • It facilitates routing by allowing blocks of addresses to be grouped together into single routing table entries.

Source:

http://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing


An example for cidr l.jpg
An example for CIDR

  • Different CIDR prefixes are used in different locations for routing

Outside MCI network

Inside MCI network

Inside ARS network


Weaknesses in internet addressing l.jpg
Weaknesses in Internet Addressing

  • If a computer moves from one network to another, its IP address must change.

    • This is the main source of challenge for mobile IP.

  • The path used for hosts with multiple IP addresses (multi-homed hosts) depends on the address used.

  • If host B connection to network 1 fails, packets from host A that uses I3 address can not reach host B.


Address aggregation l.jpg
Address Aggregation

Source: “Computer Networking: A Top-Down Approach” by J.F. Kurose, K.W. Ross


More specific routes l.jpg
More specific routes

Source: “Computer Networking: A Top-Down Approach” by J.F. Kurose, K.W. Ross


Mapping internet address to physical address l.jpg
Mapping Internet Address to Physical Address

  • Consider two machines A and B on the same network.

  • IA, IB are internet addresses and PA, PB are physical addresses of A and B respectively.

  • A wants to send a packet to B, but it only has IB address of B.

  • Address Resolution Protocol (ARP) resolves this problem for networks with static address and broadcast capability.


Slide28 l.jpg
ARP

  • Host A has an ARP cache of recently acquired IP-to-physical address bindings.

  • If IB is not in the cache, then A broadcasts an ARP request containing IB.

  • Host B responds with an ARP reply to A that contains (IB, PB). It also adds (IA, PA) to its own cache.

  • Sender A queues all packets destined to B until it receives ARP reply.

  • Expiring timer for the binding entries in the cache.

  • Resending the request (at least once) if did not get a reply.

  • In most technologies a single type value is used for ARP frames.

    • In Ethernet type field of (0806)16 is for ARP messages.


Slide29 l.jpg
RARP

  • A machine uses Reverse Address Resolution Protocol (RARP) to get its IP address from the server at the startup.

  • The server has a list of IP addresses of the machines.

  • Machine uses its physical address to communicate on the network.


Ip packet datagram delivery l.jpg
IP Packet (Datagram) delivery

  • The maximum size of an IP datagram is 216 octets.

  • It is more efficient to carry each IP packet in a network frame (encapsulation).

  • Each technology has a different maximum frame size

    • Ethernet 1500 octets

    • FDDI 4470 octets

  • IP chooses a appropriate initial datagram size.

  • Fragmentation is the process of dividing larger packets into smaller ones to adhere to the network Maximum Transfer Unit (MTU).

  • Destination uses the Identification, Flags, and Fragment offset to reassembly the packet.


Time to live field l.jpg
Time To Live field

  • Time To Live field specifies how long a packet is allowed to be in the Internet.

  • The source sets the maximum time that the datagram should survive.

  • Each router decrement this field by one when it process the packet.

  • To take into account buffering delay, each router records arrival time and decrement the field by seconds that packet stays in the router.

  • When TTL reaches zero, the router discards the packet.


Ip routing l.jpg
IP routing

  • Direct Delivery:

    Transmission of packets from one machine across a SINGLE physical network to another.

  • Indirect Delivery:

    Destination is not connected directly to the network of the sender, hence sender should pass the packet to a router for delivery.


Direct delivery l.jpg
Direct Delivery

  • Does not involve the router.

  • Sender encapsulates the datagram in a single physical frame.

  • Binds the destination IP address to a physical hardware address using ARP (if needed).

  • How does the sender know if the destination is directly connected to the same network?


Indirect delivery l.jpg
Indirect Delivery

  • Host (sender):

    Encapsulates the datagram in a physical network frame and send it to a router attached to the network.

  • Router:

    Extracts the encapsulated datagram,

    Decides the next router to send the datagram to.

    Encapsulates the Datagram for transmission over the next network.

  • Question:

    How a router and host decide next router to send the datagram to?


Ip routing table l.jpg
IP Routing Table

  • Every host and router has a routing table

  • Routing table has information about destination and how to reach them.

  • We can not have a separate entry for every possible destination.

  • First refinement: We can have a single entry for all hosts connected to the same network and only check the netid part of the internet address.

  • Second refinement: We only need to keep the information for the next hop not the entire path for each destination.

  • All next hop routers listed in router M routing table must lie on networks to which M connects directly.


Routing table l.jpg
Routing Table

  • Longest Prefix Match:

    • Recall that in CIDR more than one table entry may match the destination address.

    • The one with largest prefix number is used for routing.

    • Routing Table Entries:

      • 192.168.0.0/16

      • 192.168.20.16/28

  • Default Routes:

    • A default route is used by a router or a server when no other known route works for a packet destination address.

    • The default route in CIDR is 0.0.0.0/0

    • Hosts and routers in an organization generally point the default route towards the router that has connection to a network service provider

Both entries match the destination

address 192.168.20.19, but the second

one with larger prefix number is used.

Source:Wikipedia


Example route selection in cisco routers l.jpg
Example: Route Selection in Cisco Routers

  • This example is based on the “Route Selection in Cisco Routers, Document ID: 8651 available at:

    http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094823.shtml


Routing table38 l.jpg
Routing Table

There are three process involved in building and maintaining the routing table:

  • Various Routing Process, which run a routing protocol such as:

    • Enhanced Interior Gateway Routing Protocol (EIGRP)

    • Border Gateway Protocol (BGP)

    • Intermediate System-to-Intermediate System (IS-IS)

    • Open Shortest Path First (OSPF)

  • The routing table, which accepts information from routing process and replies to requests from the forwarding process.

  • The forwarding process, which requests information from the routing table for packet forwarding.


Building the routing table l.jpg
Building the Routing Table

Main considerations in building the routing table:

  • Administrative Distance: This indicates how much we trust source of the route.

  • Metric: This is a measure used by the routing protocol to calculate the best path to a given destination.

  • Prefix length


Routing table entry update l.jpg
Routing Table Entry Update

Assume there are four routing process running:

  • EIGRP, OSPF, RIP, IGRP

  • All 4 process learned various routes to 192.168.24.0/24 and each has chosen its best path to that network using its internal metrics and process.

  • Each routing process attempts to install their route in the routing table.

  • The one with lowest administrative distance (EIGRP here) can install its route in the routing table

  • Other routes may be used as backup routes


Prefix lengths l.jpg
Prefix Lengths

  • Assume the three routing process have received these routes:

    • EIGRP (internal): 192.168.32.0 / 26

    • RIP: 192.168.32.0 / 24

    • OSPF: 192.168.32.0 / 19

  • ALL these routes will be installed in the routing table, since they have different prefix length.

  • Routing Table:

    ....

    D 192.168.32.0/26 via 10.1.1.1

    R 192.168.32.0/24 via 10.1.1.2

    O 192.168.32.0/19 via 10.1.1.3

    ....

A packet destined for 192.168.32.1 is forwarded to 10.1.1.1, which has the longest prefix match (26 bits verses 24 or 19 bits).

A packet destined for 192.168.32.100 is forwarded to 10.1.1.2, because it does NOT fall within 192.168.32.0/26 (192.168.32.0—192.168.32.63).

But it falls within the 192.168.32.0/24 destination (192.168.32.0-192.168.32.255)



Dynamic host configuration protocol dhcp l.jpg
Dynamic Host Configuration Protocol (DHCP)

  • The router IP addresses are typically configured manually, often remotely with a network management tool.

  • Host addresses is typically configured using the DHCP protocol.

  • DHCP can give a host the same IP address each time it connects to the network or assign a temporary IP address that will be different each time the host connects to the network

  • DHCP also provides additional information such as subnet mask, address of the first hop router (default gateway) and address of the local DNS server.

  • DHCP is also used commonly in residential access networks and in wireless LANs.


Dhcp architecture l.jpg
DHCP architecture

  • DHCP is a client-server protocol

  • Newly arriving hosts are clients

  • DHCP server has the information requested by the clients

  • Subnets may have a DHCP server

  • If there is no server in a subnet, a DHCP relay agent knows the address of a DHCP server for that network

Source:http://www.windowsitpro.com/Files/5181/Figure_02.gif


Dhcp 4 step process l.jpg
DHCP 4-step process

  • DHCP server discovery: Newly arriving host sends DHCPDISCOVER message a UDP packet to port 67. This message is broadcasted.

  • DHCP sservers respond with DHCPOFFER, which is again broadcasted. The message cotains the transaction ID, the proposed IP address, the network mask, lease time.

  • The client will choose one server offer and respond to that server with a DHCPrequest message.

  • The server responds with DHCPACK

When the renewal timer expires

When the rebinding timer expires

Source:http://www.windowsitpro.com/Files/5181/Figure_01.gif


Mobility management l.jpg
Mobility Management

  • Home Network: The permanent home of a mobile node.

  • Home Agent: The entity within the home network that performs the mobility management functions.

  • Foreign Network: The network where the mobile node is currently residing.

  • Foreign Agent: The entity in the foreign network that help the mobile node with the mobility management functions.

  • Correspondent: The entity that wants to communicate with the mobile node


Mobile network architecture l.jpg
Mobile Network Architecture

Source: “Computer Networking: A Top-Down Approach” by J.F. Kurose, K.W. Ross


Addressing na ve approach l.jpg
Addressing (Naïve Approach)

  • Foreign Network advertises to its neighbors that it has a highly specific route to the mobile node permanent IP address.

  • When mobile node leaves one foreign network and joins another the new foreign network, the new foreign agent would advertise that it has a specific route and the old one eould withdraw its routing information.

  • Drawback: Scalability; it completely destroys the hierarchical structure of IP addresses.


Addressing for mobile l.jpg
Addressing for mobile

  • Foreign agent is located at the edge of the foreign network.

  • Foreign agent creates a care-of address (COA) for the mobile node, with the network portion of the COA matching that of the foreign network.

  • Note that there are two addresses for the mobile node:

    • Permanent address

    • Foreign address

  • The foreign agent informs the home agent that the mobile node is in its network and has the given COA.


Indirect routing to a mobile node l.jpg
Indirect Routing to a Mobile Node

  • The correspondent addresses the packet to the mobile node’s permanent address.

  • The packet is first routed to the mobile node home agent.

  • The home agent forwards the packet to a mobile node in two steps:

    • The packet is first forwarded to the foreign agent using the COA

    • From the foreign agent to the mobile node.

  • Mobile node can address directly its packets to the correpondent.


Indirect forwarding l.jpg
Indirect Forwarding

Source: “Computer Networking: A Top-Down Approach” by J.F. Kurose, K.W. Ross


Encapsulation and decapsulation l.jpg
Encapsulation and Decapsulation

  • Home agent encapsulates packets

  • Foreign agent decapsulates packets

Source: “Computer Networking: A Top-Down Approach” by J.F. Kurose, K.W. Ross


Network layer functionality to support mobility l.jpg
Network Layer Functionality to Support Mobility

  • Mobile Node to Foreign Agent: The mobile node registers with the foreign agent and deregisters when it leaves the network.

  • Foreign Agent to Home Agent: Foreign agent registers the mobile node ‘s COA with the home agent. Does it need to deregister the COA when the mobile node leaves its network?

  • Home Agent Packet Encapsulation: Encapsulation and forwarding of the original packets within a packet with the COA address

  • Foreign Agent Decapsulation: Extraction of the correspondent’s original packet and forwarding of it to the mobile node.


ad