IB7200 - connectivity in ICT4D

Lecture 3 DNS - domain name system

 Mapping name and ipnumbers.

 Forward: name to number

 nic.lth.se. IN A 130.235.20.3

 Reverse: number to name

 3.20.235.130.in-addr.arpa. IN PTR nic.lth.se.

DNS lookup Routing protocols

 Packets need to find way through net

 Static routing:

 Each way is added manually.

 Normally don’t use, gets messy very soon…

 Instead use dynamic routing Routing info protocol (RIP)

 Simple, early protocol.

 Distance vector. (low overhead)

 Rip v2 better.

 Never use rip v1. Avoid rip v2 Dynamic routing - OSPF

 Open Shortest Path First (OSPF)

 Used inside organisation.

 Very stable and compatible between vendors.

 Uses link state algoritm:

 All routers know the whole topology.

 Requires more computational power (no problem today) Border Gateway Protocol (BGP)

 Used between organizations (borders)

 Between autonomous systems (AS)

 Each AS has a number 0-65000

 Can decide “policy routing” like not allowing traffic from some AS.

My ORG Other ORG BGP OSFP AS y AS x Summary

 Use OSPF internally + BGP externally

External AS2 External AS1 BGP BGP

OSFP Multicast

 Send to many on a network.

 Internet Group Management Protocol (IGMP).

 Adresses 224.0.0.0 to 239.255.255.255

 PIM - protocol independent multicast

 Within an organisation

 Multicast Source Discovery Protocol (MSDP)

 Between organisations IPv6

 128 bit addreses.  Written in hex.

 2001:6b0:1:1d20:214:c2ff:fe3a:5eec/64

 64 bit net + 4 bit host

 Host is normally 12 bit fill + 48 bit mac-addr

 Each “nibble” (character) is 4 bit  KTH has 2001:6b0:1::/48

 2001:06b0:0001 ie we have 2^18 networks each with 2^64 hosts… Wireless

 Local area - WiFi - WLAN 802.11*

 Metro - WIMAX 802.16

 Wide area - GPRS: GSM, UMTS-3G

 VSAT - slow expensive but necesary in some places.

 Satellite telephony - slow, expensive 802.11*

 802.11b

 2.4Ghz, 11mbps, typical 5 mps, ~100 m  802.11g

 2.4 Ghz, 54mbps, typical 20 mbps  802.11a

 5.3 Ghz, 54mbps, typical 20 mbps  802.11n (draft)

 2.4 GHz or 5 GHz, 540 Mbit/s, 200 Mbit/s ~50 meters (~165 ft) Wireless in campus design.

 Used for point to point  Today 802.11 works well.  Up to 40 km. Normally shorter.  Use redundant links.  Directional antennas for longer distances.  Sometimes a point-to-multipoint Wireless links

Layer3 switch

Backup wlan Long distance links AIR-ANT3338 antenna guide + overview

 http://www.cisco.com/en/US/products/hw/wireless/ps 469/products_data_sheet09186a008008883b.html

 http://forskningsnett.uninett.no/wlan/radio.html Wimax for backhaul

Wimax WLAN subscriber AP

Wimax center Wimax WLAN subscriber AP

Wimax WLAN subscriber AP ADSL and tunneling.

 Sometimes you can get ADSL to a campus. Then you can use VPN-boxes like openWRT.

 Adsl operator vpn Internet

Central VPN vpn router

vpn Cisco 1841 + HWIC-3G-GSM

 Wireless Wan High-Speed WAN Interface Linksys 3G

 WRT54G3G Open source:

 Linux bridges, routers and firewalls

 Vyatta - supports open software router “Xorp”.

 OpenWrt – linux access points (see later) Linux

 Iptables – filter on IP-level – advanced.  Ebtables – filter on briding level.  Swedish router ”bifrost”  ”Captive portal” for network login. Wireless nets.

 OpenWrt

 Linux based.

 Free software for wireless access points

 Linkssys, Asus, Netgear etc. Chapter 5. IP Chapter 1. Networking Objectives Section 5.1. IP-Addressing Basics Section 1.1. Business Requirements Section 5.2. IP-Address Classes Section 1.2. OSI Protocol Stack Model Section 5.3. ARP and ICMP Section 1.3. Routing Versus Bridging Section 5.4. Network Address Translation Section 5.5. Multiple Subnet Broadcast Section 5.6. General IP Design Strategies Section 5.7. DNS and DHCP Chapter 6. IP Dynamic Routing Section 6.1. Static Routing Section 1.4. Top-Down Design Philosophy Section 6.2. Types of Dynamic Routing Protocols Chapter 2. Elements of Reliability Section 6.3. RIP Section 2.1. Defining Reliability Section 6.4. IGRP and EIGRP Section 2.2. Redundancy Section 6.5. OSPF Section 2.3. Failure Modes Section 6.6. BGP Chapter 3. Design Types Chapter 8. Elements of Efficiency Section 3.1. Basic Topologies Section 8.1. Using Equipment Features Effectively Section 3.2. Reliability Mechanisms Section 8.2. Hop Counts Section 3.3. VLANs Section 8.3. MTU Throughout the Network Section 3.4. Toward Larger Topologies Section 8.4. Bottlenecks and Congestion Section 3.5. Hierarchical Design Section 8.5. Filtering Section 3.6. Implementing Reliability Section 8.6. Quality of Service and Traffic Shaping Section 3.7. Large-Scale LAN Topologies Chapter 9. Network Management Chapter 4. Local Area Network Technologies Section 9.1. Network-Management Components Section 4.1. Selecting Appropriate LAN Technology Section 9.2. Designing a Manageable Network Section 4.2. Ethernet and Fast Ethernet Section 9.3. SNMP Section 4.4. Gigabit and 10 Gigabit Ethernet Section 9.4. Management Problems Section 4.5. ATM Chapter 10. Special Topics Section 4.7. Wireless Section 10.1. IP Multicast Networks Section 4.8. Firewalls and Gateways Section 10.2. IPv6 Section 4.9. Structured Cabling Section 10.3. Security