Zte ZXR10 5900E Product Description page 37

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Support static route, RIP, OSPF and BGP access between PE and CE
3.2.6.3 MPLS TE FRR
MPLS TE fast reroute is a mechanism in MPLS TE for link protection and node protection.
When LSP link or node fails, it takes protection at the node. In this way it permits the
traffic to continue going through the tunnel of the protected link or node so that the data
transmission will not be interrupted. At the same time the head node can continue
initiating re-establishment of main path with data transmission uninfluenced.
The basic principle of MPLS TE fast reroute is to use one established LSP to protect one
or multiple LSP. The established LSP is called fast reroute LSP. The protected LSP is
called main LSP. The ultimate purpose of MPLS TE fast reroute is to use fast reroute
tunnel to bypass the tunnel or node with failure, so as to protect the main path.
The establishment of fast reroute LSP and main LSP involves every component of MPLS
TE system.
MPLS TE fast reroute is based on the implementation of RSVP TE. It follows RFC4090.
There are two ways to implement fast reroute:
One-to-one Backup: one to one backup protection: one main LSP establishes one
backup protection LSP, which is called Detour LSP.
Facility Backup: one to multiple backup protection. Multiple main LSP establish one
backup protection LSP, which is called Bypass Tunnel.
Facility is usually adopted to deploy MPLS TE FRR. The establishment of main LSP is
the same with that of common LSP. RSVP sends PATH message from the head node to
the downstream hop-by-hop, and sends RESV message from the tail node to the
upstream hop-by-hop. It distributes labels when it deals with RESV message to reserve
the resource and establish LSP. Bypass Tunnel can be established in two ways: manual
and automatic. When main LSP is not equipped with FRR attribute, Bypass Tunnel can
be manually configured to protect the physical interface of the tunnel. Its configuration is
the same with that of the common LSP except the fact that it cannot be configured with
fast reroute. That is to say, Bypass Tunnel cannot work as main LSP at the same time.
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ZXR10 5900E Product Description
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