H3C S9500 Series Operation Manual page 7

Operation Manual – MPLS OAM
H3C S9500 Series Routing Switches
immediately. If a protection group is configured properly, the corresponding
protection switching would also be triggered.
When configuring MPLS OAM basic capability, you need to bind a reverse channel to
the LSP to be verified. A reverse channel is an LSP which has an ingress node and an
egress node contrary to the LSP to be verified. There are two types of reverse
channels:
Dedicated reverse channel: Each forward LSP has its own reverse channel. This
means is rather stable but may incur wasted resources.
Shared reverse channel: Multiple forward LSPs have a reverse channel in
common. All the LSPs transmit BDI packets through this LSP. This means
reduces wasted resources. However, the shared reverse channel may be
congested when defects are detected on multiple forward LSPs at the same time.
Configuring additional acknowledgement information for BDI packets is required in
order for the ingress node to distinguish which forward LSP has defects depending
on the BDI packets received. For example, TTSI is configured for the MPLS OAM.
As a result, a BDI packet can carry the TTSI information of the LSP to be verified,
which is useful for checking the BDI packet is necessary.
II. Protection switching
Protection switching (PS) is designed to establish the corresponding protection LSP
(secondary LSP) for the primary LSP. The primary LSP and the secondary LSP
constitute a protection group. In protection switching mode, once the primary LSP fails,
data flows can be switched to the secondary LSP rapidly, significantly improving the
reliability of networks.
In real world, you also can manually input some switching commands as required to
switch from the primary LSP to the secondary LSP, or vice versa. Manual switching and
signaling switching are prioritized. For manual switching, the switching takes effect only
when its priority is higher than the priority of the current signaling.
For PS, four modes are supported: 1:1 protection, 1+1 protection, share mesh
protection and packet 1+1 protection.
1:1 protection: Two LSPs in primary/secondary mode are available between the
ingress node and the egress node. In general, data is transported over the primary
LSP; when the ingress node detects some defect on the primary LSP through
verification mechanism (for example, OAM) and needs to run protection switching,
it switches data to the secondary LSP and keeps on transmission.
1+1 protection: Two LSPs in primary/secondary mode are available between the
ingress node and the egress node. In general, the ingress node sends the same
data packets to these two LSPs at the same time; but the egress node only
receives the data from the primary LSP. When the egress node detects some
defect on the primary LSP, it stops receiving data from the primary LSP and
switches to the secondary LSP to receive data.
Chapter 1 MPLS OAM Configuration
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