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C
HAPTER
16
| IP Configuration
Address Resolution Protocol
– 487 –
traffic passes along the path to its final destination in this way, with each
routing device mapping the destination IP address to the MAC address of
the next hop toward the recipient, until the packet is delivered to the final
destination.
If there is no entry for an IP address in the ARP cache, the switch will
broadcast an ARP request packet to all devices on the network. The ARP
request contains the following fields similar to that shown in this example:
When devices receive this request, they discard it if their address does not
match the destination IP address in the message. However, if it does
match, they write their own hardware address into the destination MAC
address field and send the message back to the source hardware address.
When the source device receives a reply, it writes the destination IP
address and corresponding MAC address into its cache, and forwards the IP
traffic on to the next hop. As long as this entry has not timed out, the
switch will be able forward traffic directly to the next hop for this
destination without having to broadcast another ARP request.
Also, if the switch receives a request for its own IP address, it will send
back a response, and also cache the MAC of the source device's IP address.
S
ETTING
THE
ARP
T
IMEOUT
Use the IP > ARP (Configure General) page to specify the timeout for ARP
cache entries.
CLI R
EFERENCES
P
ARAMETERS
These parameters are displayed:
Timeout
– Sets the aging time for dynamic entries in the ARP cache.
(Range: 300 - 86400 seconds; Default: 1200 seconds or 20 minutes)
The ARP aging timeout can only be set globally for all VLANs.
The aging time determines how long dynamic entries remain in the
cache. If the timeout is too short, the switch may tie up resources by
repeating ARP requests for addresses recently flushed from the table.
When a ARP entry expires, it is deleted from the cache and an ARP
request packet is sent to re-establish the MAC address.
Table 35: Address Resolution Protocol
destination IP address
10.1.0.19
destination MAC address ?
source IP address
10.1.0.253
source MAC address
00-00-ab-cd-00-00
Содержание DG-FS4526E
Страница 4: ...ABOUT THIS GUIDE 4...
Страница 34: ...CONTENTS 34...
Страница 50: ...TABLES 50...
Страница 52: ...SECTION I Getting Started 52...
Страница 62: ...CHAPTER 1 Introduction System Defaults 62...
Страница 80: ...CHAPTER 2 Initial Switch Configuration Managing System Files 80...
Страница 82: ...SECTION II Web Configuration 82...
Страница 100: ...CHAPTER 3 Using the Web Interface Navigating the Web Browser Interface 100...
Страница 128: ...CHAPTER 4 Basic Management Tasks Resetting the System 128...
Страница 166: ...CHAPTER 5 Interface Configuration VLAN Trunking 166...
Страница 198: ...CHAPTER 6 VLAN Configuration Configuring VLAN Mirroring 198...
Страница 516: ...CHAPTER 17 IP Services Displaying the DNS Cache 516...
Страница 562: ...CHAPTER 19 Using the Command Line Interface CLI Command Groups 562...
Страница 652: ...CHAPTER 22 SNMP Commands 652...
Страница 660: ...CHAPTER 23 Remote Monitoring Commands 660...
Страница 714: ...CHAPTER 24 Authentication Commands Management IP Filter 714...
Страница 802: ...CHAPTER 27 Interface Commands 802...
Страница 824: ...CHAPTER 29 Port Mirroring Commands RSPAN Mirroring Commands 824...
Страница 846: ...CHAPTER 32 Address Table Commands 846...
Страница 874: ...CHAPTER 33 Spanning Tree Commands 874...
Страница 886: ...CHAPTER 34 ERPS Commands 886...
Страница 928: ...CHAPTER 35 VLAN Commands Configuring Voice VLANs 928...
Страница 942: ...CHAPTER 36 Class of Service Commands Priority Commands Layer 3 and 4 942...
Страница 998: ...CHAPTER 38 Multicast Filtering Commands Multicast VLAN Registration 998...
Страница 1022: ...CHAPTER 39 LLDP Commands 1022...
Страница 1064: ...CHAPTER 40 CFM Commands 1064...
Страница 1084: ...CHAPTER 42 Domain Name Service Commands 1084...
Страница 1090: ...CHAPTER 43 DHCP Commands DHCP Client 1090...
Страница 1122: ...CHAPTER 44 IP Interface Commands IPv6 Interface 1122...
Страница 1124: ...SECTION IV Appendices 1124...
Страница 1129: ...APPENDIX A Software Specifications Management Information Bases 1129 Trap RFC 1215 UDP MIB RFC 2013...
Страница 1130: ...APPENDIX A Software Specifications Management Information Bases 1130...
Страница 1152: ...COMMAND LIST 1152...
Страница 1161: ......
Страница 1162: ...DG FS4526E 042012 HW R01...