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Configuration Guide - Ethernet Switching

S7700 and S9700 V200R012C00

This document describes the configuration of Ethernet services, including configuring MAC address table, link aggregation, VLANs, VLAN aggregation, MUX VLAN, VLAN termination, Voice VLAN, VLAN mapping, QinQ, GVRP, VCMP, STP/RSTP/MSTP, VBST, SEP, RRPP, ERPS, LBDT, HVRP, and Layer 2 protocol transparent transmission.
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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).
Working Process

Working Process

Through dynamic VLAN registration and aging mechanism, HVRP ages the VLANs that are not used to forward packets on an interface and saves only necessary VLANs. When a VLAN contains one or two interfaces, MAC addresses do not need to be learned. Instead, data packets are broadcast in the VLAN without affecting the bandwidth.

In Figure 21-2:
  • STP is enabled on the entire network, and the HVRP root interface and HVRP designated interfaces are calculated through STP.

  • The switches are connected through trunk interfaces. All trunk interfaces are enabled with HVRP and can forward packets of VLAN 101 through VLAN 500.

  • HVRP is disabled on STP edge interfaces.

Figure 21-2 shows HVRP networking. The HVRP working mechanism is described based on this networking.
Figure 21-2  HVRP working mechanism

SwitchA is the root bridge. Links between SwitchD and SwitchE are blocked by STP. The VLANs created on each switch include all user VLANs on the ring.

Generally, data packets of users connected to SwitchD are forwarded by the interface connecting SwitchD to SwitchB. The interface connecting SwitchD to SwitchE does not forward packets of VLAN 101 through VLAN 200 to other devices. Based on the Layer 2 forwarding principle:
  • When there are more than two interfaces on a Layer 2 switch, the switch searches the MAC address table for the outbound interface based on the destination MAC address in the packet. If no outbound interface is found, the switch broadcasts a packet to all interfaces.
  • When there are only two interfaces on a Layer 2 switch, the switch forwards the data packet through the other interface but not the receive interface. The switch does not need to search the destination MAC address or establish a MAC address entry.
Three interfaces on SwitchD belong to VLAN 101 through VLAN 200, so SwitchD must learn MAC addresses. However, the interface connecting SwitchD to SwitchE does not forward packets of VLAN 101 through VLAN 200 to other devices. HVRP deletes the interfaces that do not forward packets from VLANs so that the switch does not need to learn MAC addresses. This reduces the number of MAC addresses that the switch learns and improves stability and manageability of the switch.

VLAN Registration

Each switch periodically sends VLAN registration packets from the root interface to register VLANs of the local switch. For example, SwitchD periodically sends VLAN registration packets of VLAN 101 through VLAN 200 to other devices on the ring through the root interface. After receiving a VLAN registration packet from SwitchD, SwitchB registers VLAN 101 through VLAN 200 with the interface that receives the VLAN registration packet and forwards the packet upstream through the root interface.

SwitchB sends VLAN registration packets of local user VLAN 301 to VLAN 400 through the root interface. After receiving VLAN registration packets from SwitchB and VLAN registration packets of SwitchD forwarded by SwitchB, SwitchA registers VLANs of SwitchB and SwitchD on the interface that receives the packets. SwitchA is the root bridge, so it does not forward or generate VLAN registration packets.

The following are some important points on VLAN registration:
  • VLANs can be registered only on designated interfaces.
  • A VLAN can be registered on an interface only after the interface is manually added to the VLAN. For example, if an HVRP designated interface does not belong to VLAN 999, VLAN 999 cannot be registered on this interface even if the interface receives a registration packet of VLAN 999.

VLAN Aging

If a switch does not receive any registration packets containing a registered VLAN within a certain period of time, the VLAN is deleted from the non-root interface.

VLAN aging is implemented only on HVRP non-root interfaces. VLANs on the HVRP root interface never age out because all packets must pass through the HVRP root interface.

SwitchB is used as an example to describe VLAN aging on a switch. SwitchB is on a ring, and has a root interface, a designate interface, and a non-HVRP interface.
  • The interface connected to users is a non-HVRP interface and does not age out VLANs.
  • The interface connected to SwitchA is the HVRP root interface, so VLANs on this interface will never be aged out.
  • The interface connecting to SwitchD is an HVRP designated interface and is manually added to VLAN 101 through VLAN 500. This interface periodically receives registration packets of VLAN 101 through VLAN 200 from SwitchD. VLAN 101 through VLAN 200 are not aged out, but VLAN 201 through VLAN 500 are aged out after the aging time.

After the VLANs are aged out, VLAN 101 through VLAN 200 contain only the interface connected to SwitchA and the interface connected to SwitchD. VLAN 301 through VLAN 400 contain only the interface connected to SwitchA and the interface connected to users. Therefore, SwitchB does not need to learn MAC addresses in VLAN 101 through VLAN 500. After receiving data packets of a VLAN on an interface, SwitchB only needs to forward the packets through the other interface in the VLAN.

Sending and Maintaining Local VLAN Information

The HVRP root interface periodically sends local VLAN registration packets according to the VLAN registration timer.

When the role of a local VLAN changes, for example, the VLAN is not a local VLAN any more because the configuration is changed, the switch sends the local VLAN information through the HVRP root interface immediately.

Re-registering VLANs When the Status of an HVRP Interface Changes to Up or Down

Interface status change indicates that the status of an interface changes to Up or Down.

When the status of an HVRP interface changes to Up or Down, the aged VLANs may interrupt forwarding of Layer 2 packets on the entire network. Therefore, when a switch detects that the status of an HVRP interface changes, the switch immediately notify all the other switches on the network. The switches re-register the aged VLANs on the original interfaces.

Re-registering VLANs When the STP Role of an HVRP Interface Changes

After STP is enabled globally, each interface on a switch plays as a role, such as root interface, designated interface, and backup interface.

When the role of an HVRP interface changes, aged VLANs on the interface may interrupt the forwarding of Layer 2 packets over the entire network. Therefore, when a switch detects that the role of an HVRP interface is changed, the switch re-registers the aged VLANs on the original interface.

Updating Interfaces in a VLAN

  • The number of interfaces is updated in a VLAN each time an interface is added to or deleted from the VLAN, the VLAN is registered, or the VLAN is aged.

  • Physical interfaces that belong to the Eth-Trunk interface are counted as one interface.

Learning MAC Addresses in a VLAN

  • When a VLAN contains more than two non-aged interfaces, the switch learns MAC addresses.

  • When a VLAN contains two or fewer non-aged interfaces, the switch does not learn MAC addresses. In addition, the dynamic MAC addresses learned before are deleted.

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Updated: 2019-01-18

Document ID: EDOC1100038843

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