MPLS-Enabled Applications: Emerging Developments and New Technologies

13.5. VISIBILITY

A big part of management is about gaining visibility into the network. What exactly is visibility? The answer is different for different people. For example, for a network operations engineer, it may be the ability to see the path that traffic is taking or to determine if a site in a VPN went down, while for an engineer doing capacity planning, it may be the ability to build the traffic matrix between two PEs.

Management information bases (MIBs) play a big role in affording visibility into the network. As explained at the beginning of this chapter, MIBs are available for all the protocols and applications developed in the IETF and can be used to manage the network as described in [MPLS-NM]. MIBs can be used not just for reporting the state of a service or protocol but also for finding network-wide information that is not readily available otherwise. For example, for RSVP, the path of an LSP is known from the RRO Object, but for LDP, this information is not available from the protocol. However, using the label information from the LDP MIB, the path of the LDP LSP can be traced without the need to issue an LSP trace.

SNMP traps can be sent to indicate errors, such as an LSP being torn down. The receipt of the traps at the network management station provides not just an alarm indication to the operator but also valuable information about what failures happened at the same time, allowing correlation of events in the network and identification of the root cause of ...