CSEE W4140 Networking Laboratory

1. CSEE W4140Networking Laboratory Lecture 12: Review Jong Yul Kim 04.22.2009

2. Annoucements • Visit to TelioSonera’s NY POP • Meet in front of Broadway and 116th st main gate at starting time. • Wednesday group: 1 pm • Friday group: 10 am • Can you join the Friday group?

3. ICANN • Internet Corporation for Assigned Names and Numbers

4. IANA • Is run by ICANN • Provides global coordination of • Domain names (manages root) • IP addresses • AS numbers • Protocol assignments

5. Registry Listing Registry Listings from ICANN

6. Regional Internet Registries (RIRs) • Registration and management of IP address is done by Regional Internet Registries (RIRs) • Where do RIRs get their addresses from: IANA maintains a high-level registry that distributes large blocks to RIRs • RIR are administer allocation of: • IPv4 address blocks • IPv6 address blocks • Autonomous system (AS) numbers

7. Regional Internet Registries (RIRs)

8. Tiered hierarchy of ISPs

9. Tier-1 ISPs • Tier-1 ISPs form the backbone of the Internet • Directly connected to each other for free: this is called peering. • Tier-2 ISPs and other networks connect to them for a fee: this is called transit. • International presence

10. What happens if Tier-1 ISPs fight each other? • Excerpts from “Sprint, Cogent in Peering Feud” by Karl Bode as published in dslreports.com. • “A high profile dispute with Swedish telecom operator Telia in March cut off access to vast swaths of Europe.” • “The latest fight came last night, when Cogent announced that Sprint pulled the plug on their connection with the Cogent network, impacting a significant amount of both URLs and broadband customers.”

11. Point-of-Presence (POP) • A location where ISPs interconnect with each other. • Usually houses a group of routers and switches that are shared among the ISPs. • Also known as Internet Exchange Points (IXP)

12. Routing Protocols • BGP for interdomain routing • RIP and OSPF for intradomain routing • RIP is a distance vector protocol. • Count-to-infinity is a problem. • There are ways to deal with the problem. • OSPF is a link state protocol. • All routers have the same routing information. • Unless they are divided into two-level hierarchy called areas.

13. LAN and switches • In setting up a LAN, you can use routers, hubs, and switches. • Routers vs. switches • Hubs vs. switches • Switches have nice properties. • Plug-and-play through learning algorithm • Spanning Tree Protocol to avoid loops

14. IP addressing and subnets • IP addresses • have two parts: prefix and host. (CIDR notation: 10.0.2.0/24) • Prefixes are used by routers to forward packets to the correct destination • Subnets • Are divided by routers and hosts. • Every machine in a subnet uses the same prefix. • What happens if a machine’s netmask is different from the subnet’s prefix?

15. ARP • ARP is used to find the MAC address of the machine that uses a particular IP address. • ARP is used within a subnet. • Unless a router uses proxy ARP to forward ARP requests to another subnet. • There are many other uses of ARP. • IP conflict detection • RARP for IP address configuration

16. NAT and DHCP • NAT • is an outcome of the shortage of IPv4 addresses. • But they can be used in many different applications, e.g. support migration between service providers. • NAT can be problematic for some applications. • DHCP is used to configure hosts within a subnet automatically. • Relays can be used to traverse subnets.

17. SNMP • SNMP is used for network management. • The information objects are structured as a tree. (OID reflects the tree structure.) • Four parts: MIBs, SMI, the protocol, and security.

18. Homework • No prelabs due this Friday • Lab report 9 due next week by the normal dates