ASIST Administração de Sistemas

Transcription

1 ASIST Administração de Sistemas Aula 1 9 de Outubro de 2006 Alexandre Bragança Bibliografia: IBM Redbook: TCP/IP Tutorial and Technical Overview, Adolfo Rodriguez, John Gatrell, John Karas, Roland Peschke

2 TCP/IP Protocol Stack ASIST - Aula1, 9/10/2006 2

3 Client/Server Model TCP is a peer-to-peer, connection-oriented protocol. There are no master/slave relationships. The applications, however, typically use a client/server model for communications. ASIST - Aula1, 9/10/2006 3

4 IP Addressing First Byte Class Network Mask "A" "B" "C" ASIST - Aula1, 9/10/2006 4

5 Subnets Subnet masks are often abbreviated using a forward slash "/" and the number of "one" bits in the mask. For example, a network with a subnet mask of can be expressed as /24 (since is 24 binary ones followed by eight binary zeros.) Therefore, a /25 subnet is a subnet with a mask of , and a /26 subnet has a mask of , etc. ASIST - Aula1, 9/10/2006 5

6 Intranets - private IP addresses Another approach to conserve the IP address space is described in RFC 1918 Address Allocation for Private Internets. This RFC relaxes the rule that IP addresses must be globally unique. It reserves part of the global address space for use in networks that do not require connectivity to the Internet. Typically these networks are administered by a single organization. Three ranges of addresses have been reserved for this purpose: : A single Class A network through : 16 contiguous Class B networks through : 256 contiguous Class C networks ASIST - Aula1, 9/10/2006 6

7 Connecting Networks Bridge interconnects LAN segments at the network interface layer level and forwards frames between them. A bridge is said to be transparent to IP. That is, when an IP host sends an IP datagram to another host on a network connected by a bridge, it sends the datagram directly to the host and the datagram "crosses" the bridge without the sending IP host being aware of it. ASIST - Aula1, 9/10/2006 7

8 Connecting Networks Router interconnects networks at the internetwork layer level and routes packets between them. The router must understand the addressing structure associated with the networking protocols it supports and take decisions on whether, or how, to forward packets. Routers are able to select the best transmission paths and optimal packet sizes. The basic routing function is implemented in the IP layer of the TCP/IP protocol stack, so any host or workstation running TCP/IP over more than one interface could, in theory and also with most of today's TCP/IP implementations, forward IP datagrams. However, dedicated routers provide much more sophisticated routing than the minimum functions implemented by IP. ASIST - Aula1, 9/10/2006 8

9 Connecting Networks Gateway interconnects networks at higher layers than bridges and routers. A gateway usually supports address mapping from one network to another, and may also provide transformation of the data between the environments to support end-to-end application connectivity. Gateways typically limit the interconnectivity of two networks to a subset of the application protocols supported on either one. ASIST - Aula1, 9/10/2006 9

10 Routing When sending data to a remote destination, a host passes datagrams to a local router. The router forwards the datagrams towards the final destination. They travel from one router to another until they reach a router connected to the destination s LAN segment. ASIST - Aula1, 9/10/

11 Trace Routing Program utilities: Traceroute (Unix) Tracert (Windows) An example: D:\WINDOWS>tracert ns.orbis.net Tracing route to ns.orbis.net [ ] over a maximum of 30 hops: 1 1 ms 1 ms 1 ms ms 61 ms 64 ms ms 62 ms 65 ms tamino.summit-ops.orbis.net [ ] 4 78 ms 77 ms 78 ms ns.orbis.net [ ] Trace complete. ASIST - Aula1, 9/10/

12 Network Simulator Packet Tracer 4.0 (Cisco Systems, Inc.) Packet Tracer 4.0 is a standalone, mediumfidelity, simulation-based learning environment for networking novices to design, configure, and troubleshoot computer networks. Demonstration ASIST - Aula1, 9/10/