Project(1(grading((&((midterm(review(15‐441(Computer(Networks,(Spring(2010(RecitaAon(#8(Project(1(results(• Avg:(87(• Med:(98(• STD:(27.3(• Max:(100(• Min:(0(0(5(10(15(20(25(30(35(40(45(2(Project(1(grading(rubric((1/2)(• Checkpoints(–(15(points(– Does(it(pass(the(tests(in(the(checkpoint(scripts?(• Server(core(networking(–(20(points(– Handling(connecAons,(concurrency,(etc…(• Protocol(implementaAon(–(25(points(– Does(it(implement(the(required(commands(– Some(people(had(trouble(with(WHO(and(LIST(3(Project(1(grading(rubric((2/2)(• Robustness(–(25(points(– Does(it(crash(or(segfault?(– Specific(tests:(• Client(disconnects(without(calling(quit(• Send(unknown(commands(• Send(long(command(with(more(than(512(bytes(• Style(–(15(points(– DocumentaAon,(code(structure,(command(line(opAons,(etc(4(Midterm(results((5(• Avg:(59.5(• Med:(59(• STD:(10.4(• Max:(78(• Min:(28(0(2(4(6(8(10(12(14(A(–(True(or(False( For(a(bandwidth(of(t(Hz,(noise(is(1/8th(of(the(received(signal(strength,(can(you(get(2t(bits(per(second?(X Both(Manchester(and(NRZI(can(handle(long(strings(of(1’s(and(long(strings(of(0’s( UDP(is(a(beger(choice(than(TCP(for(a(real(Ame(voice(applicaAon((X Modern(high(speed(routers(use(shared(busses(to(gain(benefits(from(staAsAcal(mulAplexing.(( Modern(high(speed(routers(use(virtual(output(queues(to(avoid(head‐of‐line(blocking.((6(A(–(Longest(prefix(match(implementaAons(7(• Binary(trie((B)(vs(Patricia(trie((P)(vs(direct(high‐radix(trie((D)(• Fewest(lookups(needed?(D(because(it(is(direct.(• Requires(backtracking?(P(because(you(can(a(take(to(big(a(leap(while(following(a(link.(• Most(memory(efficient?(P(because(you(compress(nodes(with(a(single(child.(A(–(DNS((1/2)(• A(asks(for(www.foo.com,(nothing(in(cache:(1. C(asks(L;(2. L(asks(A_root;(3. A_root(tells(L(to(ask(A_com;(4. L(asks(A_com,(A(com(tells(L(to(ask(A_foo.com;(5. L(asks(A_foo.com;((6. A_foo.com(answers(to(L;(7. L(answers(to(C.((8(A(–(DNS((2/2)(• A(asks(for(kp.foo.com,(www.foo.com(in(cache:(1. C(asks(L;(2. L(asks(A_foo.com;(3. A_foo.com(answers(to(L;(4. L(answers(to(C.(9(B(–(Ethernet((1/4)(• 8(–(Why(48(bit(addresses(if(16(would(be(enough?(• Gives(us(the(uniqueness(property,(this(means:(– no(configuraAon(necessary(for(hooking(up(a(new(node;((– separaAon(of(rouAng(from(addressing;((– a(basis(for(unique(idenAficaAon(of(files,(programs(and(other(objects(on(the(networked(hosts.(• Common(mistakes:(saying(the(addresses(need(to(be(unique(in(the(whole(world,(they(don’t.(We(were(looking(for(the(advantages(that(the(uniqueness(property(gives.((10(B(–(Ethernet((2/4)(• 9(b)(What(to(do(to(ensure(collision(detecAon(when(increasing(the(bandwidth(10(Ames?(– Increase(the(minimum(packet(size(x10(– Decrease(the(wire(length(x10(• Common((mistakes:(opAc(fiber(is(not(10x(faster,(it(won’t(solve(the(problem!(11(B(–(Ethernet((3/4)(• 9(c)(1Gbps(network.(Node(starts(sending(aker(hearing(100(bits(and(it(collides(with(you(aker(you(send(700(bits.(How(far(is(he(from(you?(12(B(–(Ethernet((4/4)(• 9(c)(conAnued(700(=(2x(+(100(((x(=(300(bits(Prop_delay((=(300/10^9(=(3(x(10^‐7(s((Dist(=(Prop_delay(*(1.8(x(10^8(=(54(m(• Common(mistakes:(no(calculaAons,(using(600(or(100(bits(instead(of(300.(((((13(C(–(BGP(RelaAonships((1/4)(14(Invalid(–(violates(valley(free(rouAng(on(the(P(to(Q(link(C(–(BGP(RelaAonships((2/4)(15(Valid!(C(–(BGP(RelaAonships((3/4)(16(Invalid(–(violates(valley(free(rouAng(on(the(Q(to(P(link,(Q(is(loosing(C(–(BGP(RelaAonships((4/4)(• 11(a)(Can(AS(Q(prevent(outbound(traffic(from(going(through(AS(R?(– Yes,(just(announce(routes(through(other(ASs(• 11(b)(Can(AS(R(simply(stop(serving(AS(R’s(costumers?(– No,(it(needs(to(announce(reachability(to(AS(R(to(its(costumers(17(D(–(Repeaters,(Bridges,(Routers(and(Tunneling((1/5)(18(Everyone(will(hear(it!(Source(Dest(Hub(Hub( Hub(Hub(D(–(Repeaters,(Bridges,(Routers(and(Tunneling((2/5)(19(A(doesn’t(forward(to(D!(Source(Dest(Hub(Switch( Hub(Hub(D(–(Repeaters,(Bridges,(Routers(and(Tunneling((3/5)(20(No(one(overhears(the(packet!(Source(Dest(Switch(Switch( Switch(Switch(D(–(Repeaters,(Bridges,(Routers(and(Tunneling((4/5)(Header&type&Source&Address&Des1na1on&address&Link‐layer(MAC‐H1(MAC‐H4(IP(IP‐H1(IP‐H4(21(13(a)(A(is(a(switch,(B,(C(and(D(are(hubs.((A(packet(is(sent(from(H1(to(H4,(what(do(the(headers(look(like(while(crossing(the(B‐A(link?(13(b)(They(are(all(routers.(Header&type&Source&Address&Des1na1on&address&Link‐layer(MAC‐B(MAC‐A(IP(IP‐H1(IP‐H4(D(–(Repeaters,(Bridges,(Routers(and(Tunneling((5/5)(Header&type&Source&Address&Des1na1on&address&Link‐layer(MAC‐B(MAC‐A(IP(IP‐B(IP‐C(IP(IP‐H1(IP‐H4(22(13(c)(A,(B,(C(and(D(are(all(routers.((There(is(an(IP‐in‐IP(tunnel(from(B(to(C.(A(packet(is(sent(from(H1(to(H4,(what(do(the(headers(look(like(while(crossing(the(B‐A(link?(ParAng(thoughts(• SAll(62.5%(of(points(up(for(grabs!(• Don’t(forget(to(submit(Project(2(CP2(today.(•
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