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NE40E V800R010C10SPC500 Feature Description - Virtual Access 01

This is NE40E V800R010C10SPC500 Feature Description - Virtual Access
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Reliability of IP RAN Virtual Cluster Access

Reliability of IP RAN Virtual Cluster Access

PWs and LSPs Established for Virtual Cluster Access

As shown in Figure 2-15, the primary and secondary PWs are established for each AP to form PW redundancy. The LSP bound to each PW has a hot-standby LSP.
Figure 2-15 PWs and LSPs established for virtual cluster access

Fault Detection

BFD is used to detect faults for virtual cluster access. BFD has different implementation methods for the following services:
  • Ethernet services: When virtual cluster access is deployed to carry Ethernet services, BFD sessions are automatically established for virtual cluster access LSPs and PWs.
  • ATM/TDM services: When virtual cluster access is deployed to carry ATM/TDM services, BFD sessions are automatically established for virtual cluster access LSPs. You need to manually configure BFD for PW on a master. The master triggers an AP to establish BFD sessions for PWs to an RSG, implementing end-to-end BFD for PW.

Bit Error Detection

Virtual cluster access supports bit error detection for both VPs and VCs. When a VP's or VC's BER exceeds the configured switching threshold, VP or VC switching will be triggered to improve network reliability.

  • VP bit error detection: Bit error detection is enabled on the master, and VP switching thresholds are configured. An AP collects information about bit errors that occur on the inbound interfaces of the forward and backward VPs and advertises the BER information to the master. A master collects information about bit errors that occur on the inbound interface of the backward VP and stores the information locally. Therefore, a master can obtain the BER of each interface on the forward and backward VPs and use these BERs to calculate the BERs of the forward and backward VPs. The master stores the BER of the forward VP locally and uses a virtual cluster access packet to advertise the BER of the backward VP to the tail AP.
  • VC bit error detection for Ethernet services:
    • Upstream traffic (from left to right): An AP obtains the BER of the backward VP and uses it as the BER of the backward VC. If the VC is in the bit error state, the AP switches VCs based on switching rules.
    • Downstream traffic (from right to left): A master obtains the BER of the forward VP and uses it as the BER of the forward VC. If the VC is in the bit error state, the master sets the backup service attribute on the Remote-AP interface. The RSG is then notified of the state and determines whether to perform a downstream traffic switchover. If the bit error status of a VC changes from the excessive BER state to the normalized BER state, the master sets the main service attribute on the Remote-AP interface for the VC.
  • VC bit error detection for TDM services:

    An internal PW (VC) is established between the master and AP in the virtual cluster, and an external PW is established between the master and RSG. The two PWs form a multi-segment PW (PW), so that E2E BFD for MS-PW can be used.

    • Upstream traffic (from left to right): After E2E BFD for MS-PW detects a fault between the AP and RSG1, the AP switches traffic to the secondary PW, which then transmits traffic to the backup master. After the backup master transmits the traffic to RSG2 over the external PW, RSG2 forwards the traffic to RSG1 over the ICB PW. Finally, RSG1 forwards the traffic to the BSC/RNC.
    • Downstream traffic (from right to left): After E2E BFD for MS-PW detects a fault between RSG1 and the AP, RSG1 forwards traffic received from the BSC/RNC to RSG2 over the ICB PW. After RSG2 forwards the traffic to the backup master over the external PW, the backup master forwards the traffic to the AP over the internal PW. Finally, the AP forwards traffic to the BTS/NodeB

Protection Switching

When a link or node on the access ring with virtual cluster access deployed fails, traffic protection switching is triggered.

Fault Location 1: Link or node between the AP and primary master

  • Data Plane Switching

    Before switching, traffic travels along the primary LSP. After switching, traffic travels along the backup LSP. In this scenario, only LSP switching is performed. Figure 2-16 shows the LSPs before and after switching.
    Figure 2-16 LSPs before and after switching
  • Control Plane Switching

    Because the primary master does not fail, the control plane remains unchanged.

Fault Location 2: Primary master

  • Data Plane Switching

    Before switching, traffic travels along the primary LSP. After switching, traffic travels along the backup LSP. In this scenario, PW switching is performed. Figure 2-17 shows the LSPs before and after switching.
    Figure 2-17 LSPs before and after switching
  • Control Plane Switching

    The secondary master automatically becomes the new primary master, and the control plane switches to the secondary master. If the original primary master recovers, traffic switches back to the original. However, the control plane remains located on the new primary master.

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Updated: 2019-01-03

Document ID: EDOC1100055053

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