These roles define the relationships between all devices so that each device can monitor the layers under its
responsibility. Maintenance points drop all lower-level frames and forward all higher-level frames.
Figure 5-2. Maintenance Points
Customer Network
Maintenance End Points
A Maintenance End Point (MEP) is a logical entity that marks the end-point of a domain. There are two
types of MEPs defined in 802.1ag for an 802.1 bridge:
•
Up-MEP: monitors the forwarding path internal to an bridge on the customer or provider edge; on
Dell Force10 systems the internal forwarding path is effectively the switch fabric and forwarding
engine.
•
Down-MEP: monitors the forwarding path external another bridge.
Configure Up- MEPs on ingress ports, ports that send traffic towards the bridge relay. Configure
Down-MEPs on egress ports, ports that send traffic away from the bridge relay.
Figure 5-3. Up-MEP versus Down-MEP
Customer Network
towards relay
Up-MEP
Down-MEP
Service Provider Network
Ethernet Access
Operator Domain (5)
MEP
Service Provider Ethernet Access
away from relay
MPLS Core
MIP
Customer Network
MPLS Access
Operator Domain (5)
802.1ag | 81