Dell PowerConnect B-RX BigIron RX Series Configuration Guide v02.7.02 - Page 221

IP forwarding cache, Basic IP parameters and defaults, When parameter changes take effect

Page 221 highlights

Basic IP parameters and defaults 7 IP forwarding cache The device maintains a software cache table for fast processing of IP packets that are forwarded or generated by the CPU. The cache also contains forwarding information that is normally contained in the IP routing table. For example, the cache contains information on the physical outgoing port, priority, VLAN, and the type of cache entry. Also, cache entries have hardware information, which is useful for debugging and aging. There are two types of IP cache entries. 1. Directly connected host entries - These entries are created when the CPU receives the first packet destined to a directly connected host. Host entries are set to age out after a certain period if no traffic is seen for that entry. 2. Network entries - These entries are created when a route table entry is created in software. These entries are not subjected to aging. A route table entry is created when routes are learned by routing protocols such as OSPF or when routes are statically configured. Here is an example of an entry in the IP forwarding cache. IP Address Next Hop 1 192.168.1.11 DIRECT MAC 0000.0000.0000 Type Port Vlan Pri PU n/a 0 Each IP forwarding cache entry contains the IP address of the destination, and the IP address and MAC address of the next-hop router interface to the destination. If the destination is actually an interface configured on the device itself, as shown here, then next-hop information indicates this. The port through which the destination is reached is also listed, as well as the VLAN and Layer 4 QoS priority associated with the destination if applicable. To display the IP forwarding cache, refer to "Displaying the forwarding cache" on page 219. Basic IP parameters and defaults IP is enabled by default. The following protocols are disabled by default: • Route exchange protocols (RIP, OSPF, BGP4) • Multicast protocols (IGMP, PIM-DM, PIM-SM, DVMRP) • Router redundancy protocols (VRRPE, VRRP, FSRP) When parameter changes take effect Most IP parameters described in this chapter are dynamic. They take effect immediately, as soon as you enter the CLI command. You can verify that a dynamic change has taken effect by displaying the running configuration. To display the running configuration, enter the show running-config or write terminal command at any CLI prompt. To save a configuration change permanently so that the change remains in effect following a system reset or software reload, save the change to the startup configuration file. Enter the write memory command from the Privileged EXEC level of any configuration level of the CLI. Changes to memory allocation require you to reload the software after you save the changes to the startup configuration file. When reloading the software is required to complete a configuration change, the procedure that describes the configuration change includes a step for reloading the software. BigIron RX Series Configuration Guide 149 53-1001810-01

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  • 1,312
  • 1,313
  • 1,314
  • 1,315
  • 1,316
  • 1,317
  • 1,318
  • 1,319
  • 1,320
  • 1,321
  • 1,322
  • 1,323
  • 1,324
  • 1,325
  • 1,326
  • 1,327
  • 1,328
  • 1,329
  • 1,330
  • 1,331
  • 1,332
  • 1,333
  • 1,334
  • 1,335
  • 1,336
  • 1,337
  • 1,338
  • 1,339
  • 1,340
  • 1,341
  • 1,342
  • 1,343
  • 1,344
  • 1,345
  • 1,346
  • 1,347
  • 1,348
  • 1,349
  • 1,350
  • 1,351
  • 1,352
  • 1,353
  • 1,354
  • 1,355
  • 1,356
  • 1,357
  • 1,358
  • 1,359
  • 1,360
  • 1,361
  • 1,362
  • 1,363
  • 1,364
  • 1,365
  • 1,366
  • 1,367
  • 1,368
  • 1,369
  • 1,370
  • 1,371
  • 1,372
  • 1,373
  • 1,374
  • 1,375
  • 1,376
  • 1,377
  • 1,378
  • 1,379
  • 1,380
  • 1,381
  • 1,382
  • 1,383
  • 1,384
  • 1,385
  • 1,386
  • 1,387
  • 1,388
  • 1,389
  • 1,390
  • 1,391
  • 1,392
  • 1,393
  • 1,394
  • 1,395
  • 1,396
  • 1,397
  • 1,398
  • 1,399
  • 1,400
  • 1,401
  • 1,402
  • 1,403
  • 1,404
  • 1,405
  • 1,406
  • 1,407
  • 1,408
  • 1,409
  • 1,410
  • 1,411
  • 1,412
  • 1,413
  • 1,414
  • 1,415
  • 1,416
  • 1,417
  • 1,418
  • 1,419
  • 1,420
  • 1,421
  • 1,422
  • 1,423
  • 1,424
  • 1,425
  • 1,426
  • 1,427
  • 1,428
  • 1,429
  • 1,430
  • 1,431
  • 1,432
  • 1,433
  • 1,434
  • 1,435
  • 1,436

BigIron RX Series Configuration Guide
149
53-1001810-01
Basic IP parameters and defaults
7
IP forwarding cache
The device maintains a software cache table for fast processing of IP packets that are forwarded or
generated by the CPU. The cache also contains forwarding information that is normally contained in
the IP routing table. For example, the cache contains information on the physical outgoing port,
priority, VLAN, and the type of cache entry. Also, cache entries have hardware information, which is
useful for debugging and aging.
There are two types of IP cache entries.
1.
Directly connected host entries
These entries are created when the CPU receives the first
packet destined to a directly connected host. Host entries are set to age out after a certain
period if no traffic is seen for that entry.
2.
Network entries
– These entries are created when a route table entry is created in software.
These entries are not subjected to aging. A route table entry is created when routes are
learned by routing protocols such as OSPF or when routes are statically configured.
Here is an example of an entry in the IP forwarding cache.
Each IP forwarding cache entry contains the IP address of the destination, and the IP address and
MAC address of the next-hop router interface to the destination. If the destination is actually an
interface configured on the device itself, as shown here, then next-hop information indicates this.
The port through which the destination is reached is also listed, as well as the VLAN and Layer 4
QoS priority associated with the destination if applicable.
To display the IP forwarding cache, refer to
“Displaying the forwarding cache”
on page 219.
Basic IP parameters and defaults
IP is enabled by default.
The following protocols are disabled by default:
Route exchange protocols (RIP, OSPF, BGP4)
Multicast protocols (IGMP, PIM-DM, PIM-SM, DVMRP)
Router redundancy protocols (VRRPE, VRRP, FSRP)
When parameter changes take effect
Most IP parameters described in this chapter are dynamic. They take effect immediately, as soon
as you enter the CLI command.
You can verify that a dynamic change has taken effect by
displaying the running configuration.
To display the running configuration, enter the
show
running-config
or
write terminal
command at any CLI prompt.
To save a configuration change permanently so that the change remains in effect following a
system reset or software reload, save the change to the startup configuration file.
Enter the
write
memory
command from the Privileged EXEC level of any configuration level of the CLI.
Changes to memory allocation require you to reload the software after you save the changes to the
startup configuration file.
When reloading the software is required to complete a configuration
change, the procedure that describes the configuration change includes a step for reloading the
software.
IP Address
Next Hop
MAC
Type
Port
Vlan
Pri
1
192.168.1.11
DIRECT
0000.0000.0000
PU
n/a
0