H3C Technologies H3C S12500-X Series Switches - Manual (Page 20)

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An MA serves the specified VLAN or no VLAN. An MA that serves a VLAN is considered carrying VLAN
attribute. An MA that serves no VLAN is considered having no VLAN attribute. An MP can receive
packets sent by other MPs in the same MA. The level of an MA equals the level of the MD that the MA
belongs to.
Maintenance point
An MP is configured on a port and belongs to an MA. MPs include the following types: maintenance
association end points (MEPs) and maintenance association intermediate points (MIPs).
• MEP
MEPs define the boundary of the MA. Each MEP is identified by a MEP ID.
The MA to which a MEP belongs defines the VLAN of packets sent by the MEP. The level of a MEP
equals the level of the MD to which the MEP belongs. The level of packets sent by a MEP equals the
level of the MEP.
The level of a MEP determines the levels of packets that the MEP can process. A MEP forwards
packets at a higher level and processes packet of its level or lower. The processing procedure is
specific to packets in the same VLAN. Packets of different VLANs are independent.
MEPs include inward-facing MEPs and outward-facing MEPs:
{
An outward-facing MEP sends packets to its host port.
{
An inward-facing MEP does not send packets to its host port. Rather, it sends packets to other
ports on the device.
• MIP
A MIP is internal to an MA. It cannot send CFD packets actively; however, it can handle and
respond to CFD packets. By cooperating with MEPs, a MIP can perform a function similar to ping
and traceroute. A MIP forwards packets of a different level without any processing and only
processes packet of its level.
The MA to which a MIP belongs defines the VLAN of packets that the MEP can receive. The level
of a MIP is defined by its generation rule and the MD to which the MIP belongs. MIPs are
generated on each port automatically according to related MIP generation rules:
{
Default rule—If no lower-level MIP exists on an interface, a MIP is created on the current level.
A MIP can be created even if no MEP is configured on the interface.
{
Explicit rule—If no lower-level MIP exists and a lower-level MEP exists on an interface, a MIP is
created on the current level. A MIP can be created only when a lower-level MEP is created on
the interface.
If a port has no MIP, the system will check the MAs in each MD (from low to high levels), and follow
the procedure as described in
Figure 3 to create or not to create MIPs at the current level.