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NE40E V800R010C10SPC500 Feature Description - Network Reliability 01

This is NE40E V800R010C10SPC500 Feature Description - Network Reliability
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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Virtual Access over NAT Inter-chassis Hot Backup for Indirect Links

Virtual Access over NAT Inter-chassis Hot Backup for Indirect Links

Service Overview

In the virtual access over NAT inter-chassis hot backup scenario shown in Figure 11-14, the AP is dual-homed to BRAS1 and BRAS2 equipped with CGN boards. There are no direct links between BRAS1 and BRAS2. A PW tunnel is established between BRAS1 and BRAS2 using VE sub-interfaces to transparently transmit VRRP packets. A PW tunnel is established between BRAS1/BRAS2 and AP as the backup tunnel, with VRRP deployed on VE sub-interfaces to negotiate the CGN master/slave relationship and the CGN service deployed to implement NAT and associate with the VSM HA backup group and network-side interfaces. The user-side PWIF interface is associated with the VSM HA status monitoring group to associate service board faults with the user-side interface status. The network-side link is deployed with the interface monitoring group, and the internal communication interface is associated with the interface monitoring group. The internal communication interface's status automatically changes based on the status of the interface bound to the interface monitoring group.

BRAS1 functions as the master BRAS, and BRAS2 as the slave BRAS. The link between the AP and BRAS1 is the master link, and the link between the AP and BRAS2 is the backup link. Upstream traffic is sent to the network side after NAT is implemented on BRAS1, and downstream traffic is sent to the user side after NAT is implemented on BRAS1 over the CR.

Figure 11-14 Virtual access over NAT hot backup

Fault-triggered Service Switching

  • Service switching triggered by a user-side link fault

    In the virtual access over NAT inter-chassis hot backup scenario shown in Figure 11-15, the user-side link between AP and BRAS1 fails. In this case, the backup link between AP and BRAS2 functions as the master link, triggering a master/backup PW link switching. The master/backup VRRP status remains unchanged. In the upstream direction, user-side traffic is switched to BRAS2 and sent to BRAS1 for NAT implementation over the network-side PW tunnel between BRAS1 and BRAS2. Then, the traffic is sent to the network side. In the downstream direction, network-side traffic is NATed on BRAS1 and sent to the BRAS2 over the RUI protection tunnel between BRAS1 and BRAS2. Then, the traffic is sent to the user side.

    Figure 11-15 Service switching triggered by a user-side link fault
  • Service switching triggered by a network-side link fault

    In the virtual access over NAT inter-chassis hot backup scenario shown in Figure 11-16, the link between BRAS1 and CR fails, resulting in a weight decrease of the monitoring group on the internal communication interface on BRAS1. This interface becomes Down. In this case, the backup link between AP and BRAS2 functions as the master link, and a master/backup PW link switching is triggered. The VRRP priority of BRAS1 is decreased, and the VRRP status of BRAS2 changes from slave to master. Traffic is NATed on BRAS2 and then sent to the network side and user side.

    Figure 11-16 Service switching triggered by a network-side link fault
  • Service switching triggered by a device fault

    In the virtual access over NAT inter-chassis hot backup scenario shown in Figure 11-17, BRAS1 becomes faulty, resulting in a disconnection of the links between BRAS1 and peripheral devices. In this case, the backup link between AP and BRAS2 functions as the master link, and a master/backup PW link switching is triggered. The priority of BRAS1 is decreased, and the VRRP status of BRAS2 changes from slave to master. Traffic is NATed on BRAS2 and then sent to the network side and user side.

    Figure 11-17 Service switching triggered by a device fault
  • Service switching triggered by a CGN board fault

    In the virtual access over NAT inter-chassis hot backup scenario shown in Figure 11-18, the VSUF on BRAS1 becomes faulty. As VRRP is associated with the service board status, the master/backup VRRP status is changed. The VRRP priority of BRAS1 is decreased, and the VRRP status of BRAS2 changes from backup to master. The HA status monitoring group associated with the PWIF interface becomes Down. Traffic is NATed on BRAS2 and then sent to the network side and user side.

    Figure 11-18 Service switching triggered by a CGN board fault
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Updated: 2019-01-03

Document ID: EDOC1100055045

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