
C
HAPTER
18
| General IP Routing
IP Routing and Switching
– 681 –
broadcast to get the destination MAC address from the destination node.
The IP packet can then be sent directly with the destination MAC address.
If the destination belongs to a different subnet on this switch, the packet
can be routed directly to the destination node. However, if the packet
belongs to a subnet not included on this switch, then the packet should be
sent to the next hop router (with the MAC address of the router itself used
as the destination MAC address, and the destination IP address of the
destination node). The router will then forward the packet to the
destination node through the correct path. The router can also use the ARP
protocol to find out the MAC address of the destination node of the next
router as necessary.
N
OTE
:
In order to perform IP switching, the switch should be recognized by
other network nodes as an IP router, either by setting it as the default
gateway or by redirection from another router via the ICMP process.
When the switch receives an IP packet addressed to its own MAC address,
the packet follows the Layer 3 routing process. The destination IP address
is checked against the Layer 3 address table. If the address is not already
there, the switch broadcasts an ARP packet to all the ports on the
destination VLAN to find out the destination MAC address. After the MAC
address is discovered, the packet is reformatted and sent out to the
destination. The reformat process includes decreasing the Time-To-Live
(TTL) field of the IP header, recalculating the IP header checksum, and
replacing the destination MAC address with either the MAC address of the
destination node or that of the next hop router.
When another packet destined to the same node arrives, the destination
MAC can be retrieved directly from the Layer 3 address table; the packet is
then reformatted and sent out the destination port. IP switching can be
done at wire-speed when the destination address entry is already in the
Layer 3 address table.
If the switch determines that a frame must be routed, the route is
calculated only during setup. Once the route has been determined, all
packets in the current flow are simply switched or forwarded across the
chosen path. This takes advantage of the high throughput and low latency
of switching by enabling the traffic to bypass the routing engine once the
path calculation has been performed.
R
OUTING
P
ATH
M
ANAGEMENT
Routing Path Management involves the determination and updating of all
the routing information required for packet forwarding, including:
◆
Handling routing protocols
◆
Updating the routing table
◆
Updating the Layer 3 switching database
Содержание ECS4110-28T
Страница 1: ...Management Guide www edge core com ECS4110 28T 28P 52T 52P 28 52 Port Gigabit Ethernet Layer 2 Switch...
Страница 2: ......
Страница 4: ......
Страница 63: ...FIGURES 63 Figure 428 Configuring VLAN Translation 1177...
Страница 64: ...FIGURES 64...
Страница 72: ...TABLES 72...
Страница 74: ...SECTION I Getting Started 74...
Страница 102: ...SECTION II Web Configuration 102 General IP Routing on page 679...
Страница 154: ...CHAPTER 4 Basic Management Tasks Resetting the System 154...
Страница 198: ...CHAPTER 5 Interface Configuration VLAN Trunking 198 Figure 65 Configuring VLAN Trunking...
Страница 272: ...CHAPTER 9 Congestion Control Automatic Traffic Control 272...
Страница 286: ...CHAPTER 10 Class of Service Layer 3 4 Priority Settings 286...
Страница 420: ...CHAPTER 13 Security Measures DHCP Snooping 420...
Страница 566: ...CHAPTER 14 Basic Administration Protocols OAM Configuration 566...
Страница 638: ...CHAPTER 15 Multicast Filtering Multicast VLAN Registration for IPv6 638...
Страница 662: ...CHAPTER 16 IP Configuration Setting the Switch s IP Address IP Version 6 662...
Страница 678: ...CHAPTER 17 IP Services Configuring the PPPoE Intermediate Agent 678...
Страница 792: ...CHAPTER 21 System Management Commands Switch Clustering 792...
Страница 822: ...CHAPTER 23 Remote Monitoring Commands 822...
Страница 888: ...CHAPTER 24 Authentication Commands PPPoE Intermediate Agent 888...
Страница 968: ...CHAPTER 25 General Security Measures Port based Traffic Segmentation 968...
Страница 994: ...CHAPTER 26 Access Control Lists ACL Information 994...
Страница 1034: ...CHAPTER 28 Link Aggregation Commands Trunk Status Display Commands 1034...
Страница 1044: ...CHAPTER 29 Power over Ethernet Commands 1044...
Страница 1084: ...CHAPTER 33 UniDirectional Link Detection Commands 1084...
Страница 1090: ...CHAPTER 34 Address Table Commands 1090...
Страница 1194: ...CHAPTER 37 VLAN Commands Configuring Voice VLANs 1194...
Страница 1388: ...CHAPTER 42 CFM Commands Delay Measure Operations 1388...
Страница 1410: ...CHAPTER 44 Domain Name Service Commands 1410...
Страница 1420: ...CHAPTER 45 DHCP Commands DHCP Relay 1420...
Страница 1472: ...CHAPTER 46 IP Routing Commands IPv4 Commands 1472...
Страница 1474: ...SECTION IV Appendices 1474...
Страница 1502: ...COMMAND LIST 1502...
Страница 1513: ......
Страница 1514: ...ECS4110 28T ECS4110 28P ECS4110 52T ECS4110 52P E072014 ST R02 150200000929A...