CSEE W4140Networking Laboratory

Lecture 12: Review

Jong Yul Kim04.22.2009

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?

ICANN Internet Corporation for Assigned Names and Numbers

IANA

Is run by ICANN

Provides global coordination of Domain names (manages root) IP addresses AS numbers Protocol assignments

Registry Listings from ICANN

.com 1985 Unsponsored Unrestricted (but intended for commercial registrants)

VeriSign, Inc. Registry Customer Service

VeriSign Naming Services 21345 Ridgetop CircleDulles, Virginia 20166United StatesTel : +1 703 925-6999Fax: +1 703 421-5828http://www.verisign-grs.com

.edu 1985 Sponsored United States educational institutions

EDUCAUSE Becky GrangerEDUCAUSE4772 Walnut Street, Suite 206Boulder, Colorado 80301United StatesTel: +1-303-939-0334Fax: +1-303-440-0461http://www.educause.edu/edudomain

TLD IntroducedSponsored/

UnsponsoredPurpose

Sponsor/Operator

Contact

.net 1985 Unsponsored Unrestricted (but intended for network providers, etc.)

VeriSign, Inc. Registry Customer ServiceVeriSign Naming Services21345 Ridgetop CircleDulles, Virginia 20166United StatesTel: +1 703 925-6999 Fax: +1 703 421-5828 http://www.verisign-grs.com

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

Regional Internet Registries (RIRs)

Tiered hierarchy of ISPs

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

Name AS #

AT&T 7018

Global Crossing 3549

Level 3 Communications

3356

NTT Communications 2914

Qwest 209

Sprint 1239

Tata Communications 6453

Verizon Business 701

SAVVIS 3561

TeliaSonera IC 1299

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.”

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)

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.

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

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?

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

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.

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.

Homework

No prelabs due this Friday

Lab report 9 due next week by the normal dates