No relevant resource is found in the selected language.

This site uses cookies. By continuing to browse the site you are agreeing to our use of cookies. Read our privacy policy>Search

Reminder

To have a better experience, please upgrade your IE browser.

upgrade

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.
Rate and give feedback :
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).
Overview of VLAN Aggregation

Overview of VLAN Aggregation

Definition

VLAN aggregation, also called super-VLAN, partitions a broadcast domain on a physical network into multiple VLANs (sub-VLANs) and aggregates them into a single logical VLAN (super-VLAN). The sub-VLANs are addressed from the same IP subnet and share a default gateway address, thereby reducing the number of IP addresses required on the network.

Purpose

VLAN technology is commonly used on packet-switched networks because it facilitates network design. For example, it can split a large broadcast domain into smaller ones, group hosts together regardless of their location, and separate hosts, resources, and traffic. However, communication between hosts in different broadcast domains typically requires a Layer 3 switch to be configured with a Layer 3 logical interface per VLAN. This wastes IP addresses because each VLAN requires a unique subnet ID, directed broadcast address, and subnet default gateway address, none of which can be assigned as a host's IP address. In addition, the IP address block allocated to a VLAN may contain more IP addresses than required. Unused IP addresses in one VLAN cannot be used in other VLANs.

Consider the following example. In Figure 5-1, VLAN 2 contains 10 hosts. The VLAN is assigned the subnet 10.1.1.0/28, which provides 16 IP addresses. Of these addresses, 10.1.1.0 is the subnet ID, 10.1.1.15 is the directed broadcast address, and 10.1.1.1 is the default gateway address. The remaining 13 IP addresses are available for the 10 hosts, leaving three wasted IP addresses that cannot be used in other VLANs.

At least three IP addresses are wasted for VLAN 2, and at least nine IP addresses are wasted for three VLANs. Although VLAN 2 requires only 10 IP addresses, the remaining 3 IP addresses cannot be used by other VLANs and are wasted. If more VLANs are added, the problem is exacerbated.

Figure 5-1  Common VLAN scenario

To solve the preceding problem, VLAN aggregation can be used. VLAN aggregation maps each sub-VLAN to a broadcast domain, associates a super-VLAN with multiple sub-VLANs, and assigns only one IP subnet to the super-VLAN. Consequently, the gateway IP address of all sub-VLANs is the IP address of the associated super-VLAN.

By sharing the gateway address, the number of subnet IDs, subnet default gateway addresses, and directed broadcast IP addresses used is reduced. The switch assigns IP addresses to hosts in sub-VLANs according to the number of hosts. This ensures that each sub-VLAN acts as an independent broadcast domain, conserves IP addresses, and implements flexible addressing.

Translation
Download
Updated: 2019-01-18

Document ID: EDOC1100038843

Views: 94656

Downloads: 67

Average rating:
This Document Applies to these Products
Related Documents
Related Version
Share
Previous Next