Week Seven. Attendance Announcements Current Week Information Upcoming Assignments Review midterm exam. Week Seven Topics. Private, public, and NAT addressing Static or Dynamic IP Address Assignment Hierarchical Addressing, route summarization, CIDR Domain Name Server (DNS).
What has happened to IPv4 addresses?
In 1981, IPv4 Protocol was published. In 1985, about 1/16 of the total IPv4 address space was in use. By mid-2001, about 2/3 of the total IPv4 address space was in use.
Since 2001, Internet service providers have been trying to conserve IP addresses. They have assigned only a subset of addresses to customers. Currently, the number of public IP addresses available is insufficient for assigning addresses for an entire network.
The answer to this problem is to assign private addresses within a network and to translate these private addresses to public addresses when Internet connectivity is required.
Are there public, private, or both types of addressing required?
How many end systems will need access to the public network? This includes email, file transfer, or web browsing.
How many end systems require access to visible public network(s). This includes e-commerce, such as web servers, database servers, application servers, and public servers. These end systems require globally unambiguous IP addresses.
Where will the boundaries be between private and public IP addresses and how will they be implemented?
172.16.0.0 –172.31.255.255: 172.16.0.0/12
Where does the /12 come from?
12 bits in common
10101100 . 0 . 00010000 . 00000000 . 00000000 –172.16.0.0
10101100 . 00011111 . 11111111 . 11111111 –172.31.255.255
10101100 . 000100000000000 . 00000000 –172.16.0.0/12
DHCP is a superset of the BootP protocol. This means that it uses the same protocol structure as BootP, but it has enhancements added. Both of these protocols use servers that dynamically configure clients when requested. The two major enhancements are address pools and lease time.
A method supported by classless routing protocols, such as OSPF and BGP4, based on the concept of ignoring the IP class of address, permitting route aggregation and VLSM that enable routers to combine routes in order to minimize the routing information that needs to be conveyed by the primary routers. It allows a group of IP networks to appear to other networks as a unified, larger entity. In CIDR, IP addresses and their subnet masks are written as four dotted octets, followed by a forward slash and the numbering of masking bits.
172.16.0.0 255.255.0.0 = 172.16.0.0 /16
126.96.36.199 255.255.255.0 = 188.8.131.52 /24
Note that 192.168.24.0 /22 is not a Class C network, it has a subnet mask of 255.255.252.0
Given four Class C Networks (/24):
192.168.16.0 11000000 1010100000010000 00000000
192.168.17.0 11000000 1010100000010001 00000000
192.168.18.0 11000000 1010100000010010 00000000
192.168.19.0 11000000 1010100000010011 00000000
Identify which bits all these networks have in common. 192.168.16.0 /22 can represent all these networks. The router will look at the first 22 bits of the address to make a routing decision
Importance of Hierarchical Addressing
Without summarization, every small change in the network will be propagated (spread) throughout the entire network
With summarization, small changes in the network aren’t propagated (spread) throughout the entire network
Root Level Domain
Top Level Domain and Countries
(Australia com edugov net org )
Second Level Domain
( microsoftfranklincisco )