3Com SuperStack 4, Configuration Manual

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90 C
HAPTER
5: N
ETWORK
P
ROTOCOL
O
PERATION
By default, this feature is enabled.
Displaying and
Debugging ARP
After the above configuration, enter the
display
command in any view to display
the running of the ARP configuration, and to verify the effect of the configuration.
Enter the
debugging
command in User View to debug ARP configuration. Enter
the
reset
command in User View to clear ARP mapping table.
Resilient ARP
Configuration
Overview of Resilient
ARP
To support resilient networking in XRN applications, redundant links are required
between the XRN fabric and other devices. But if intra-fabric connections are
broken and the original fabric is split, these redundant links may cause a situation
where the network connects to two or more layer 3 devices of the same
configuration and they run the same routing function. To eliminate this situation,
you can resort to resilient ARP mechanism, which can immediately detect if there
are layer 3 devices of the same configuration existing in the network. If yes, it will
keep only one as a Layer 3 device and turn the others in to Layer 2 devices.
A resilient ARP state machine may be in one of six states: Initialize,
LisentForL3Master, L3Master, L3Slave, L2Master and L2Slave. An L3Master state
machine regularly sends resilient ARP messages to notify other XRN fabrics that its
home fabric is in Layer 3 state.
The resilient ARP mechanism can implement state transition by sending/receiving
resilient ARP messages regularly, so as to determine if a device serves as a Layer 3
or Layer 2 device.
Resilient ARP
Configuration
Resilient ARP configuration is described in the following sections:
■
Enabling/Disabling Resilient ARP Function
■
Configuring Resilient ARP Packet-sending VLAN Interface
Enabling/Disabling Resilient ARP Function
After resilient ARP is enabled, the system can ensure there is only one Layer 3
device, and that others are Layer 2 devices.
Table 83 Displaying and Debugging ARP
Operation Command
Display the ARP mapping table
display arp
[
ip_address
| [
dynamic
|
static
] [
| {
begin
|
include
|
exclude
}
text
] ]
Display the current setting of the
dynamic ARP map aging timer
display arp timer aging
Reset the ARP mapping table
reset arp
[
dynamic
|
static
|
interface
{
interface_type interface_num
|
interface_name
}
]
Enable ARP information
debugging
debugging arp packet
Disable ARP information
debugging
undo debugging arp packet