
376
C
HAPTER
16: IP R
OUTING
Figure 42
ARP Proxy
Internet Control
Message Protocol
(ICMP)
Because a router knows only about the next network hop, it is not aware
of problems that may be closer to the destination. Destinations may be
unreachable if:
■
Hardware is temporarily out of service.
■
You specified a nonexistent destination address.
■
The routers do not have a route to the destination network.
To help routers and hosts discover problems in packet transmission, a
mechanism called Internet Control Message Protocol (ICMP) reports
errors back to the source when routing problems occur. With ICMP, you
can determine whether a delivery failure resulted from a local or a remote
problem.
Server A
Server B
158.101.1.2
(255.255.0.0)
158.101.2.1
(255.255.0.0)
158.101.2.2
(255.255.0.0)
With Proxy ARP enabled
the MAC address of Server B
is returned to Server A because
the subnetworks are transparent
Содержание 4007
Страница 1: ...http www 3com com Switch 4007 Implementation Guide Release 3 0 5 Part No 10013673 Published May 2000 ...
Страница 36: ...36 ABOUT THIS GUIDE ...
Страница 37: ...I UNDERSTANDING YOUR SWITCH 4007 SYSTEM Chapter 1 Configuration Overview ...
Страница 38: ......
Страница 50: ...50 CHAPTER 1 CONFIGURATION OVERVIEW ...
Страница 52: ......
Страница 70: ...70 CHAPTER 3 INSTALLING MANAGEMENT MODULES ...
Страница 110: ...110 CHAPTER 4 CONFIGURING AND USING EME OPTIONS ...
Страница 130: ...130 CHAPTER 5 MANAGING THE CHASSIS POWER AND TEMPERATURE ...
Страница 222: ...222 CHAPTER 11 IP MULTICAST FILTERING WITH IGMP ...
Страница 240: ...240 CHAPTER 13 RESILIENT LINKS ...
Страница 304: ...304 CHAPTER 14 VIRTUAL LANS VLANS ...
Страница 350: ...350 CHAPTER 15 PACKET FILTERING ...
Страница 506: ...506 CHAPTER 19 OPEN SHORTEST PATH FIRST OSPF ROUTING ...
Страница 534: ...534 CHAPTER 20 IPX ROUTING ...
Страница 612: ...612 CHAPTER 22 QOS AND RSVP ...
Страница 656: ...656 CHAPTER 23 DEVICE MONITORING ...
Страница 657: ...IV REFERENCE Appendix A Technical Support Index ...
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