H3C Technologies H3C S12500 Series Switches - Manual (Page 39)

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{
The port stays in DOWN state even if you enable the IRF link auto-recovery function. To bring
the port up, use the undo shutdown command.
{
If the IRF fabric splits, the physical IRF ports in DOWN state change to the previous state.
Configuring MAD
The following MAD mechanisms are available for detecting multi-active collisions in different network
scenarios:
• LACP MAD
• BFD MAD
• ARP MAD.
LACP MAD handles collisions in a different way than BFD MAD and ARP MAD. To avoid conflicts, do not
use LACP MAD together with BFD MAD and ARP MAD. However, you can use BFD MAD and ARP MAD
together.
Table 1 provides a reference for you to make a MAD mechanism selection decision.
Table 1 A comparison of the MAD mechanisms
MAD
mechanism
Advantages Disadvantages Application scenario
LACP MAD
• Detection speed is fast.
• Requires no
MAD-dedicated physical
ports or interfaces.
Requires an intermediate H3C
device that supports LACP
MAD packets.
Link aggregation is used
between the IRF fabric and
its upstream or downstream
device.
For information about
LACP, see Layer 2—LAN
Switching Configuration
Guide.
BFD MAD
• Detection speed is fast.
• No intermediate device
is required.
• Intermediate device, if
used, can come from any
vendor.
• Requires MAD dedicated
physical ports and Layer 3
interfaces, which cannot
be used for transmitting
user traffic.
• If no intermediate device is
used, the IRF members
must be fully meshed.
• If an intermediate device is
used, every IRF member
must connect to the
intermediate device.
• No special requirements
for network scenarios.
• If no intermediate device
is used, this mechanism
is only suitable for IRF
fabrics that have a small
number of members that
are geographically
close to one another.
For information about BFD,
see High Availability
Configuration Guide.
ARP MAD
• No intermediate device
is required.
• Intermediate device, if
used, can come from any
vendor.
• Requires no MAD
dedicated ports.
• Detection speed is slower
than BFD MAD and LACP
MAD.
• The spanning tree feature
must be enabled.
Spanning tree-enabled
non-link aggregation IPv4
network scenario.
For information about ARP,
see Layer 3—IP Services
Configuration Guide.