2 networking
0 likes88 views
IPv4 and IPv6 are protocols that assign numeric addresses to devices to enable communication and routing of information across the internet. DNS is a hierarchical system that maps human-friendly domain names to these numeric IP addresses. It uses caching and time-to-live values to improve efficiency. Local networks can be merged using bridges, which expose internal addresses, or NAT, which hides internal addresses behind a single external address.
![[WSO2Con EU 2017] Jump to the Next Curve with DevOps](https://cdn.slidesharecdn.com/ss_thumbnails/jumptothenextcurvewithdevopschamithedited-171107085752-thumbnail.jpg?width=560&fit=bounds)
Ad
More Related Content
What's hot (20)
Similar to 2 networking (20)
Ad
More from Len Bass (20)
Ad
Recently uploaded (20)
![Get & Download Wondershare Filmora Crack Latest [2025]](https://cdn.slidesharecdn.com/ss_thumbnails/revolutionizingresidentialwi-fi-250422112639-60fb726f-250429170801-59e1b240-thumbnail.jpg?width=560&fit=bounds)
![Pixologic ZBrush Crack Plus Activation Key [Latest 2025] New Version](https://cdn.slidesharecdn.com/ss_thumbnails/fashionevolution2-250322112409-f76abaa7-250428124909-b51264ff-250504160528-fc2bb1c5-thumbnail.jpg?width=560&fit=bounds)
2 networking
- 1. DOSE: Deployment and Operation for Software Engineers Networking
- 2. © Len Bass 2019 2 • IP addresses • Domain Name System/Time to Live Overview
- 3. © Len Bass 2019 3 • An IP (Internet Protocol) address is a numerical label that identifies a “device” on the internet. • IPv4 is 32 bits long and gives a four number sequence - xxx.xxx.xxx.xxx • 32 bits is insufficient and so IPv6 was created in 1995 and it has 128 bits. IPv4 and IPv6
- 4. © Len Bass 2019 4 Adoption • For legacy reasons, IPv6 has had a very slow adoption. IPv4 numbers have been exhausted. This is causing more conversion to IPv6. June 8, 2011 was designated as world IPv6 day where top websites and internet providers provided a 24 hour test of IPv6 infrastructure. This test was successful.
- 5. © Len Bass 2019 5 Percentage of Users that access Google over IPv6.
- 6. © Len Bass 2019 6 Assigning IP addresses • Every “device” on the internet includes virtual machines in a cloud or in an application such as VirtualBox. • Every VM or container gets an IP address when it is created. This IP address can be • Private and not seen outside of the cloud or the application.. • Public and directly addressable from outside of the cloud. • Conventional IP addresses • 127.0.0.1 – local host – current physical machine. • 192.xx.xx.xx – private network.
- 7. © Len Bass 2019 7 IP message format • An IP message has a header and a payload. The header includes • IP address of the source • IP address of the destination
- 8. © Len Bass 2019 8 Internet Protocol packet structure (V4)
- 9. © Len Bass 2019 9 Internet Protocol packet structure (V6)
- 10. © Len Bass 2019 10 Private • Private IP addresses: • When IPA sends message to IPB, i.e., IPA+payload -> IPB , a gateway can make it look like the message comes from the gateway. i.e. IPgateway+payload -> IPB • In this case the gateway must maintain a table so that it can manage the response from IPB
- 11. © Len Bass 2019 11 Public IP addresses • The VM manager is given a range of IP addresses that it can assign to VM instances. • An assignment only lasts as long as the instance does, then it can be re-assigned. • Messages from the instances come from the assigned IP address and recipient can respond directly to instance. • The VM manager is, typically, your ISP
- 12. © Len Bass 2019 12 Merging two local networks • Bridge – appears externally to be one network. Each machine’s IP address is available from outside of the bridged network. Typically used on bare metal hypervisors and container runtime engines. • NAT (Network Address Translation) – externally there exists only one IP address. The NAT modifies the source on outgoing messages and the destination on incoming messages to route the messages. Typically used on hosted hypervisors.
- 13. © Len Bass 2019 13 Overview • IP addresses • Domain Name System/Time to Live
- 14. © Len Bass 2019 14 Domain Name System(DNS) • Client sends URL to DNS • DNS takes as input a URL and returns an IP address • Client uses IP address to send message to a site DNS serverWebsite.com 123.45.67.89 123.45.67.89
- 15. © Len Bass 2019 15 Complications • In reality, messages being transmitted from one computer to another is more complicated. • The picture showed a single DNS server. • There are multiple DNS servers • There is a hierarchy of DNS servers. • The picture showed a single line from client to server. • There is a network for routers to transmit messages • Shares load
- 16. © Len Bass 2019 16 DNS Hierarchy • Consider URL www.mse.isr.cmu.edu • If one server held all DNS -> IP mappings, it would both get overloaded and hold over 200 million mappings. • DNS is arranged as a hierarchy.
- 17. © Len Bass 2019 17 Finding www.mse.isr.cmu.edu • Begin with “root server”. There are ~13 root servers with known IP addresses. These are built into the router. (https://www.iana.org/domains/root/servers) • Access root server to get IP address of the .edu DNS • The .edu DNS has the IP of the .cmu.edu DNS and so forth. • Eventually you get to a DNS server that is under local control • This allows MSE to change the IP of the various local DNSs without changing anything up the hierarchy.
- 18. © Len Bass 2019 18 Time to Live • Clients do not access a DNS server for every request. It would generate too much internet traffic. • Associated with each DNS entry is a Time To Live (TTL). • This is also called a “Refresh Interval” in the DNS resource record called Start of Authority (SOA). • The client or the ISP caches the IP addresses associated with DNS entries and these entries are valid for the TTL. • This is distinct from the TTL listed in the IPV4 packet header.
- 19. © Len Bass 2019 19 TTL manipulation • The value of the TTL depends where in the hierarchy the record exists. • High in the hierarchy (authorative servers), TTLs are set to 24 hours since the likelihood of there being a change is low. • Records under local control can have their TTLs set low (~minutes) • We will see applications of small TTL settings when we discuss switching between different development environments.
- 20. © Len Bass 2019 20 Client (browser) perspective on DNS, URL, and TTL • Client gets ip addresses of edu from root • TTL is 24 hours • Client gets ip addresses of cmu from one of edu • TTL is 24 hours • Client gets ip addresses of mse from one of cmu • TTL is 12 hours • Client gets ip address of www from mse • TTL is 5 minutes
- 21. © Len Bass 2019 21 Summary • IP addresses tells network how to route a message to get it to a particular computer. • Merging two local networks can be done with a bridge or with a NAT • Domain Name System translates URLs into IP addresses