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2
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(Routing)
(Router)
(.. Ethernet)
(OSI 3)
/
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IP ()
Forwarding Process
(IP Forwarding Table)
1.
3.
-
2. ,
TTL
4.
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Routing WAN
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6/19
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/ ;
:
.
+
+
-
-
+
+
- - CPU, ,
-
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: - (shortest paths)
A
D E
C
B100
10020
20
80
80
20
20 10
10
10
10
10
10
Source
50
30
20 30
(source)
IP
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Distance Vectorvs. Link State
+Dijkstra
Bellman-Ford
=
-
;
.
:
RIP, EIGRP,BGP
:
OSPF, IS-IS,IDPR
(Distance Vector)
(Link State)
,
,
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RIP (Routing Information Protocol)
routing tables routers
route
OSPF (Open Shortest Path First)
.
BGP (Border Gateway Protocol) TCP
distance vector
keep-alive
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RIP
, routing table , router, ., RIP (link)
router RIP , (router), ( ) ,
n n,
RIP router o
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12/19
RIP
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RIP
Tr router l
t router , , , RIP
t 30 seconds
router . n,
Send routers
Receive ( +1=) , ,
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14/19
14
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;
/ LANs
LAN Internet LAN (segments)
WLAN LAN
15
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LANs:Hub ()
hub / LAN
/ hub, hub
16
IP
LLC
802.3 MAC
IP
LLC
802.3 MACHubHub
LAN
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LANs:switch ()
switch /,
, switch
(bridges)
17
h b h
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1818
Ethernet Hubs vs. EthernetSwitches
Ethernet switch: (buffering)
(collisions)
(collision domain)
Ethernet Hub buffering:
H
ighSpeed
B
ackplane
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
Output
Buffers
Input
Buffers
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
Hub Switch
LAN
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LANs:router ()
routers (Layer 3) IP
IP
19
IP networkIP network IP network
Router Router Host Host
Application
TCP
IP
Network
Access
Application
TCP
IP
Network
Access
IP protocol
Data
LinkNetwork
Access
IP
Network
AccessNetwork
Access
IP
Network
Access
Data
Link
Data
Link
IP protocol
RouterRouter HostHost
IP protocol
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