6



















R1
R2
R3
H1
H2




















R1
R2
R3
H1
H2


1.

(Routing)



H1
H5
H2
H4
H3
A
C
D
B
H6
E




H1
H5
H2
H4
H3
A
C
D
B
H6
E






AB


(
(
(
(
(
(
(
(



6.4



2
3


2. Frame RelayX.25
3. ATMAsynchronous Transfer Mode ATM53



3

2. IP







0
4
8
16
19
24
31



0
1
2
3
4
5
6
7
D
T
R
C




0
1
2
3
4
5
6
7
D
T
R
C




0
1
2
3
4
5
6
7
D
T
R
C




0
1
2
3
4
5
6
7
D
T
R
C

IP 4 ( IPv4)



0
4
8
16
19
24
31



0
1
2
3
4
5
6
7
D
T
R
C








—— 4 bit 15 ( 4 ) IP 60



0
4
8
16
19
24
31



0
1
2
3
4
5
6
7
D
T
R
C





0
4
8
16
19
24
31



0
1
2
3
4
5
6
7
D
T
R
C

65535



0
1
2
3
4
5
6
7
D
T
R
C




0
1
2
3
4
5
6
7
D
T
R
C





0
4
8
16
19
24
31



0
1
2
3
4
5
6
7
D
T
R
C




0
1
2
3
4
5
6
7
D
T
R
C





0
1
2
3
4
5
6
7
D
T
R
C




0
1
2
3
4
5
6
7
D
T
R
C




0
1
2
3
4
5
6
7
D
T
R
C









HA1
HA5
HA4
HA3
HA6
IP1 → IP2
IP1 → IP2
IP1 → IP2
IP1→IP2 IP1 IP2
IP IP
IP1 → IP2
IP1 → IP2
IP1 → IP2
IP1 → IP2
IP1 → IP2
IP1 → IP2


IP ICANN (Internet Corporation for Assigned Names and Numbers)

[RFC 950] 1985
1993
IP
::= “”
1 1 1 1 0
0
1
host-id
1 1 1 1 0
0
1
host-id
1 1 1 1 0
0
1
host-id
1 1 1 1 0
0
1
host-id
1 1 1 1 0
0
1
host-id
1 1 1 1 0
0
1
host-id
1 1 1 1 0
0
1
host-id
1 1 1 1 0
0
1
1 1 1 1 0
0
1
6.2 ABC

B 16,384 (214) 128.0 191.255 65,534
C 2,097,152 (221) 192.0.0 223.255.255 254

0

A
B
C
D
E

1.0.0.0
126.255.255.255
128.0.0.0
191.255.255.255
192.0.0.0
223.255.255.255
224.0.0.0
239.255.255.255
240.0.0.0
246.255.255.255



IP net-id (multihomed host)
IP IP


B
222.1.1.
222.1.1.1
222.1.1.2
222.1.1.3
222.1.1.4
R1
222.1.2.5
222.1.2.2
222.1.2.1
222.1.2.3
222.1.2.4
222.1.2.
222.1.6.1
222.1.5.1
222.1.5.2
222.1.6.2
222.1.4.1
222.1.4.2
222.1.3.3
222.1.3.2
222.1.3.1
R3
R2
222.1.3.
LAN3
N3
N2
222.1.4.
222.1.5.
222.1.6.
N1
LAN2
LAN1

IP IP “” IP

2

00000000000000000000000000000000
10.0.0.0-10.255.255.25510/8
172.16.0.0-172.31.255.255172.16/12)


subnet-id

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
0 0 0 0 0 0 0 0










AND
net-id
host-id
subnet-id
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
0 0 0 0 0 0 0 0
net-id
subnet-id
net-id
net-id
net-id

A




255.0.0.0

B




255.255.0.0

C




255.255.255.0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 1 1 1 1 1 1 1
0 0 0 0 0 0 0 0
host-id 0
host-id 0
VLSMVariable Length Subnet MaskingVLSM
Classless Routing ProtocolOSPFRIPv2EIGRPVLSM


VLSM CIDR (Classless Inter-Domain Routing)

CIDR
CIDR A B C IPv4
CIDR“”(network-prefix)
CIDR IP “CIDR”

128.14.32.0

(supernetting)
/20 20 1 1

10.0.0.0/10 IP 10.0.0.0 255.192.0.0
11111111 11000000 00000000 00000000
10.0.0.0/10 IP 10.0.0.0 255.192.0.0
11111111 11000000 00000000 00000000
00001010 00* * * IP


C




206.0.71.128/26
206.0.71.192/26
206.0.68.0/25
206.0.68.128/25
206.0.69.0/25
206.0.69.128/25
206.0.70.0/26
206.0.70.64/26
206.0.70.128/26
206.0.70.192/26
206.0.70.0/24
206.0.71.0/25
206.0.71.0/26
206.0.71.64/26
206.0.71.128/25
206.0.68.0/23
ISP 64 C CIDR ISP 64 1 206.0.64.0/18 ISP

IP



P81


Internet

PC2
PC1
IP:192.168.0.1
Port:3000
ARP (ARP cache) IP
A B IP ARP B IP MAC MAC

ARP
32IP
48MAC
ARPInternet

A
Y
X
B
Z
ARP
ARP
A ARP IP ARP
B A ARP A B ARP B A





ARP
1.1.1.1
1.1.1.2
Purpose: This figure explains how RARP works.
In layer 1, the host on the left needs its IP address. It sends a RARP request with its MAC address.

RARP
Layer 2 of 4:
In layer 2, the host on the right, functioning as a RARP server, maps the MAC address to an IP address.

RARP
ICMPICMPICMPIP“Ping”“Tracert”ICMP

8
16
31
4; 5.
2. ICMP
4Ping
2. Ping
Ping32B“-l Size”“ping 11.8.11.112 –l 1560”

Ping

Ping
4.Ping

Tracert

13.2.4 2tracert
Tracert
tracert [-d] [-h MaximumHops] [-j HostList] [-w Timeout] [-R] [-S SrcAddr] [-4][-6] TargetName
13.2.4 2tracert
3ARPIPPCBIPMACPCAMACMACPCBMACIP
ARPPCAPCBIPMACPCBPCAIPMACPCBPCAPCBARP
A:reply from 10.2.3.3:bytes=32 time<10 ms ttl=128
B:reply from 10.2.2.2:bytes=32 time<10 ms ttl=128
“ARP -a”PC
3A
A255.255.255.0
“ARP -d”ARPA“ping”BA“destination host unreachable”(
“ARP -a”


Bping AB“Request timed out”(“ARP -a”PC



1
1
1


(forwarding table)
“”“”













A
B


2
3
4


P12

Mbps,

LCD




NE40EMPLS VPN PE
NE5000ENE80ENE40EPEASBR
IP
NE40
NE40E

NE80ECN2
MPLSQoS































































(5)




2CPU6.15

ASIC
ASICASICASIC









2A :AaIP




routerconfig#ip router prefix mask {address | interface} [distance] [tag tag] [permanent

1 0.0.0.0
0.0.0.0/0IP
{adderss|interface}
routerconfig#ip default-network ip-network-number


3


reliability
cost


IGRPRIP
l  IGRP
l   IGRPVLSM
IGRPsplit horizonpoison reversetrigger updateholddown timer



OSPFInterior Gateway ProtocolIGPAS










0
4
16
31



0
4
16
31




0
4
16
31


(payload length)—— 16 bit IPv6 64 KB

0
4
16
31



0
4
16
31






0
4
16
31



2
3(Routing)
5 (Authentication)


    IANAIPv6
1.IPv6
IPv6

IPv4IPv6IPv6 x:x:x:x:x:x:d.d.d.d“x”IPv696“d”32“IPv4IPv6”“IPv4IPv6”
0:0:0:0:0:0:10.1.2.3::10.11.3.123
fec0:0:0:1::1234/64


1IPv4IPv6
IPv6IPv4IPv6IPv6IPv632IPv4“IPv4IPv6” ::192.168.0.1
3
IPv6 RFC 2374 IPv6 ::ffff:192.168.0.1

“FF”
“”“000T”“T”
“”“1”“2”“ ID”
8
4
4
112
11111111


ID

1Multicast Listener DiscoveryMLD
2Neighbor DiscoveryND

(2

l 80
l 
(2)
(4)