Transcript The Internet

The Internet
9.1:Introduction
9.2:IP datagrams
9.3:Fragmentation and reassembly
9.4:IP address
9.5:ARP and RARP
9.6:Routing algorithms
9.7:ICMP
9.8:QOS support
9.9:The PPP link layer protocol
9.10:IPv6
9.11:IPv6/IPv4 interoperability
9.1:Introduction
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MTU => maximum transmission unit
ARP:address resolution protocol
OSPF:open shortest path first
ICMP:internet control message protocol
IGMP:internet group management protocol
9.2:IP datagrams
• IPv4 =>IP version 4
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9.3:Fragmentation and reassembly
• If the size of a packet is greater than the
MTU => router or gateway divides the
information received in the packet into a
number of smaller blocks knows as
fragments
• Fig 9.4
9.4:IP address
• Address class
• An address with a hostid of all 0s is used to refer
to the network in the netid part rather than a host
• An address with a netid of all 0s implies the same
network as the source network/netid
• An address of all 1s means broadcast the packet
over the source network
• An address with a hostid of all 1s means broadcast
the packet over the destination network in the
netid part
• A class A address with a netid of all 1s is used for
test purposes within the protocol stack of the
source host.It is loopback address
9.4.1:Subnets
9.5:ARP and RARP
• 9.5.1: ARP
– Each host are two address :IP address and its
MAC address which, since it is assign to the
MAC integrated circuit when it is manufactured,
is known also as the physical address
– Fig 9.7
• 9.5.2: RARP
9.5.3:ARP/RARP message
formats and transmission
9.6:Routing algorithms
9.6.1:Static routing
9.6.2:Flooding
9.6.3:Distance vector routing
9.6.4:Link-state shortest-pathfirst routing
• Link-state algorithm
– Fig 9.14
• Dijkstra shortest-path-first algorithm
– Fig 9.15
– Fig 9.16
– Fig 9.17
9.6.5:Hierarchical routing
• Subnet router:this is a router that operates entirely
within a single network when subnetting is being
used
• Access gateway:this is used to connect an access
network to an interior gateway
• Interior gateway:this is a router that is used to
interconnect the networks within an autonomous
system
• Exterior gateway:this is a router that is used to
connect an autonomous system to the core
backbone network
Border gateway protocol
9.6.6:Classes inter-domain
routing
9.6.7:Tunneling
9.6.8:Broadcast routing
• Limited broadcast:this is used to send a copy of a
packet to the IP in all the hosts that are attached to
the same LAN segment or bridged LAN
• Subnet-directed broadcast:this is used to send a
copy of a packet to the IP in all the host that are
attached to the subnet specified in the destination
IP address
• Net-directed broadcast:this is used to send a copy
of a packet to the IP in all the host that are
attached to the network specified in the netid part
of the destination IP address
Reverse path forwarding
Spanning tree broadcast
9.6.9:Multicast routing
• Multicast over a LAN
Multicast over the Internet
• A router that can route packet containing a IP
multicast address is known as a multicast router
• In the cast of a network that comprises multiple
subnets interconnected by subnet routers, a single
subnet router also acts as the mrouter for the
network
• Each mrouter learns the set of multicast group
addresses of which all the hosts attached to the
networks which the mrouter serves are currently
members
• The information gathered by each mrouter is
passed on to each of the other mrouters so thst
each knows the complete list of group addresses
that each mrouter has an interest in
DVMRP
MOSPF
9.6.10:IGMP
9.7:IGMP
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Error reporting
Reachability testing
Congestion control
Route-change notification
Performance measuring
Subnet addressing
Fig 9.27
9.8:QOS support
• 9.8.1:Integrated services
• 9.8.2:Differentiated services
9.8.1:Integrated services
• Guaranteed:a specified maximum delay and
jitter and an assured level of bandwidth are
guaranteed
• Control load:the flow obtains a constant
level of service equivalent to that obtained
with the best effort service at light loads
• Best effort
• Token bucket filter:A portion of bandwidth of the
outgoing line and an amount of buffer space is
reserved for the packet flow relating to each call.
This is used to enforce these allocations so that the
guaranteed QOS requirements in terms of
bandwidth,delay and jitter are met.
• Weighted fair queuing:ensure the delay bounds for
each flow are met the guaranteed bounds
• Random early detection:when a packet arrives for
an output queue and the queue is full,instead of
discarding the packet, a packet that is already in
the queue is randomly selected for discarding
• Resource reservation protocol(Fig 9.28)
9.8.2:Differentiated services
• Individual flows are not identified and instead the
individual flows in each services class are
aggregated together
• Diffserv network the type of service field in the IP
packet header is replaced by a new field call DS
field
• DSCP:used to enable each router to determined
the traffic class to which the packet data relates
and the output queue into which the packet should
be put
– Fig 9.28 b
• PHB(per hop behavior):queue schedule procedure
relating to each queue
9.9:The PPP link layer protocol
9.10:IPv6
• A much increased address space from 32 bits to 128 bits
• Hierarchical address to reduce the size of the routing tables
associated with the routers in the core backbone network
• A simplified header to enable routers and gateways to process
and route packets faster
• The introduction of improved security and data integrity
features including authentication and encryption
• An autoconfiguration facility that enables a host to obtain an IP
address via the network without human intervention
• Header quality of service quarantees by means of the
preferential treatment by routers of the packets associated with
interactive and multimedia application relative to those relating
to traditional applications such as email and file transfers
• Support for mobile computing by the use of autoconfiguration to
obtain an IP address dynamically via network for the duration of
a call
9.10.1Datagram format
9.10.2:Address structure
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Unicast address
Multicast address
Anycast address
Fig 9.31
9.10.3:Extension headers
• Hop-by-hop options:information for the routers
visited along a path
• Routing:list of routers relating to source routing
information
• Fragment:information to enable the destination to
reassemble a fragmented message
• Authentication:information to enable the
destination to verify the identity of the source
• Encapsulating security payload:information to
enable the destination to decrypt the payload
contents
• Destination options:optional information for use
by the destination
• Fig 9.32
9.10.4:Autoconfiguration
9.11:IPv6/IPv4 interoperability
• 9.11.1:Dual protocols:dual stacks are
already widely used in networks that use
dissimilar protocol stacks,ex IPX and IP
• 9.11.2:Dual stacks and tunneling
– Fig 9.37
9.11.3:Translators