H3C Technologies H3C S12500 Series Switches - Manual (Page 17)

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LACP MAD handles a multi-active collision in the following procedure:
1. Compares the number of members in each fabric.
2. Sets the fabric that has the most members to the Detect state and all other fabrics to the Recovery
state.
3. If all IRF fabrics have the same number of members, compares the member IDs of their masters.
4. Sets the IRF fabric that has the lowest numbered master to the Detect state and all other fabrics to
the Recovery (disabled) state.
5. Shuts down all physical network ports in the Recovery-state fabrics except their physical IRF ports
and any ports you have specified with the mad exclude interface command.
In contrast, BFD MAD and ARP MAD do not compare the number of members in fabrics. They directly set
the IRF fabric that has the lowest numbered master to the Detect state, set all other fabrics to the Recovery
state, and take the same action on the network ports in Recovery-state fabrics as LACP MAD does.
To reduce the impact of IRF splits, H3C recommends that you specify the member device with the lowest
member ID as the master in a two-chassis IRF fabric.
Failure recovery
To merge two split IRF fabrics, first repair the failed IRF link and remove the IRF link failure.
If the IRF fabric in Recovery state fails before the failure is recovered, repair the failed IRF fabric and the
failed IRF link.
If the active IRF fabric fails before the failure is recovered, first enable the inactive IRF fabric to take over
the active IRF fabric and protect services from being affected. After that, recover the MAD failure.
LACP MAD
LACP MAD requires that every IRF member have a link with an intermediate device, and all these links
form a dynamic link aggregation group, as shown in Figure 7 . In addition, the intermediate device must
be an H3C device that supports extended LACP for MAD.
The IRF member devices send extended LACP data units (LACPDUs) with type length values (TLVs) that
convey the domain ID and active ID of the IRF fabric. The domain ID uniquely identifies an IRF device in
the network, and the active ID is identical to the member ID of the master device in the IRF fabric. The
intermediate device transparently forwards the extended LACPDUs received from one member device to
all the other member devices:
• If the domain IDs and the active IDs in the extended LACPDUs sent by all the member devices are
the same, the IRF fabric is integrated.
• If the extended LACPDUs convey the same domain ID but different active IDs, a split has occurred.
LACP MAD handles this situation as described in "
Collision handling ."