C
HAPTER
18
| General IP Routing
Equal-cost Multipath Routing
– 505 –
manually configured in the static routing table, or equal-cost multipaths
dynamically generated by the Open Shortest Path Algorithm (OSPF). In
other words, it uses either static or OSPF entries, not both. Normal unicast
routing simply selects the path to the destination that has the lowest cost.
Multipath routing still selects the path with the lowest cost, but can forward
traffic over multiple paths if they all have the same lowest cost. ECMP is
enabled by default on the switch. If there is only one lowest cost path
toward the destination, this path will be used to forward all traffic. If there
is more than one lowest-cost path configured in the static routing table
(see
"Configuring Static Routes" on page 501
), or dynamically generated
by OSPFv2 (see
"Configuring the Open Shortest Path First Protocol (Version
), then up to 8 paths with the same lowest cost can be
used to forward traffic to the destination.
CLI R
EFERENCES
u
C
OMMAND
U
SAGE
u
ECMP only selects paths of the same protocol type. It cannot be applied
to both static paths and dynamic paths at the same time for the same
destination. If both static and dynamic paths have the same lowest
cost, the static paths have precedence over dynamic paths.
u
Each path toward the same destination with equal-cost takes up one
entry in the routing table to record routing information. In other words,
a route with 8 paths will take up 8 entries.
u
The routing table can only have up to 8 equal-cost multipaths for static
routing and 8 for dynamic routing for a common destination. However,
the system supports up to 256 total ECMP entries in ASIC for fast
switching, with any additional entries handled by software routing.
u
When there are multiple paths toward the same destination with equal-
cost, the system chooses one of these paths to forward each packet
toward the destination by applying a load-splitting algorithm.
A hash value is calculated based upon the source and destination IP
fields of each packet as an indirect index to one of the multiple paths.
Because the hash algorithm is calculated based upon the packet header
information which can identify specific traffic flows, this technique
minimizes the number of times a path is changed for individual flows.
In general, path changes for individual flows will only occur when a
path is added or removed from the multipath group.
P
ARAMETERS
These parameters are displayed in the web interface:
u
ECMP Number
– Sets the maximum number of equal-cost paths to the
same destination that can be installed in the routing table.
(Range: 1-8; Default: 4)
Содержание DG-GS4826S
Страница 2: ...DG GS4826S DG GS4850S E012011 R01 F1 2 2 0 ...
Страница 4: ......
Страница 6: ...ABOUT THIS GUIDE 6 ...
Страница 60: ...SECTION I Getting Started 60 ...
Страница 72: ...CHAPTER 1 Introduction System Defaults 72 ...
Страница 90: ...CHAPTER 2 Initial Switch Configuration Managing System Files 90 ...
Страница 92: ...SECTION II Web Configuration 92 u Unicast Routing on page 539 u Multicast Routing on page 595 ...
Страница 137: ...CHAPTER 4 Basic Management Tasks Resetting the System 137 Figure 23 Restarting the Switch Regularly ...
Страница 138: ...CHAPTER 4 Basic Management Tasks Resetting the System 138 ...
Страница 204: ...CHAPTER 6 VLAN Configuration Configuring MAC based VLANs 204 ...
Страница 212: ...CHAPTER 7 Address Table Settings Clearing the Dynamic Address Table 212 ...
Страница 238: ...CHAPTER 9 Rate Limit Configuration 238 Figure 106 Configuring Rate Limits ...
Страница 268: ...CHAPTER 12 Quality of Service Attaching a Policy Map to a Port 268 ...
Страница 368: ...CHAPTER 14 Security Measures DHCP Snooping 368 ...
Страница 422: ...CHAPTER 15 Basic Administration Protocols Remote Monitoring 422 ...
Страница 466: ...CHAPTER 16 Multicast Filtering Multicast VLAN Registration 466 Figure 273 Showing All MVR Groups Assigned to a Port ...
Страница 487: ...CHAPTER 17 IP Configuration Setting the Switch s IP Address IP Version 6 487 Figure 285 Showing Reported MTU Values ...
Страница 488: ...CHAPTER 17 IP Configuration Setting the Switch s IP Address IP Version 6 488 ...
Страница 538: ...CHAPTER 20 IP Services Forwarding UDP Service Requests 538 ...
Страница 594: ...CHAPTER 21 Unicast Routing Configuring the Open Shortest Path First Protocol Version 2 594 ...
Страница 624: ...CHAPTER 22 Multicast Routing Configuring PIMv6 for IPv6 624 ...
Страница 638: ...CHAPTER 23 Using the Command Line Interface CLI Command Groups 638 ...
Страница 712: ...CHAPTER 26 SNMP Commands 712 ...
Страница 720: ...CHAPTER 27 Remote Monitoring Commands 720 ...
Страница 776: ...CHAPTER 29 Authentication Commands Management IP Filter 776 ...
Страница 876: ...CHAPTER 34 Port Mirroring Commands Local Port Mirroring Commands 876 ...
Страница 898: ...CHAPTER 37 Address Table Commands 898 ...
Страница 998: ...CHAPTER 41 Quality of Service Commands 998 ...
Страница 1060: ...CHAPTER 42 Multicast Filtering Commands MLD Proxy Routing 1060 ...
Страница 1078: ...CHAPTER 43 LLDP Commands 1078 ...
Страница 1088: ...CHAPTER 44 Domain Name Service Commands 1088 ...
Страница 1164: ...CHAPTER 47 IP Interface Commands IPv6 to IPv4 Tunnels 1164 ...
Страница 1260: ...CHAPTER 48 IP Routing Commands Open Shortest Path First OSPFv3 1260 ...
Страница 1304: ...SECTION IV Appendices 1304 ...
Страница 1310: ...APPENDIX A Software Specifications Management Information Bases 1310 ...
Страница 1343: ...DG GS4826S DG GS4850S E012011 R02 F1 2 2 0 ...
Страница 1344: ......