What is the difference between bridge domain and VLAN?
Bridge groups provide a method to group two or more ports into a single broadcast domain, where as VLAN provide a method to group many ports into a single broadcast domain or establish a number of broadcast domains (or secure groups) on a single switch.
A bridge domain is a set of logical ports that share the same flooding or broadcast characteristics. Like a virtual LAN (VLAN), a bridge domain spans one or more ports of multiple devices.
In the Cisco EVC Framework, the bridge domains are made up of one or more Layer 2 interfaces known as service instances. A service instance is the instantiation of an EVC on a given port on a given router. Service instance is associated with a bridge domain based on the configuration.
Bridge-group Groups the physical interfaces into one logical group. Interface BVI A Layer-3 that can be routed, logical interface. BDI is similar to BVI except that it runs on Cisco IOS-XE. Bridge domain Represents a Layer 2 broadcast domain.
In Junos OS Release 9.2 and later, bridge domains provide support for a Layer 2 trunk port. A Layer 2 trunk interface enables you to configure a single logical interface to represent multiple VLANs on a physical interface.
Bridging divides a single physical LAN (now called a single broadcast domain) into two or more virtual LANs, or VLANs. Each VLAN is a collection of some of the LAN nodes grouped together to form individual broadcast domains.
The simplest way to enable routing between the two VLANs to simply connect an additional port from each VLAN into a Router. The Router doesn't know that it has two connections to the same switch — nor does it need to. The Router operates like normal when routing packets between two networks.
The BD-VLAN connects different local FD-VLANs to a single bridge domain, and is used on the Broadcom ASIC to determine the Layer 2 broadcast domain. If for example two different access_enc VLANs have the same BDVlan ID it means they belong to two EPGs that are part of the same BD.
Using VLAN & Bridge
VLANs prevent traffic, including broadcasts and multicasts, from being propagated to members of other VLANs. Switches are interconnected by the Inter-Switch Link (ISL) port so that VLAN traffic can cross multiple switches. A Layer-2 switch is basically a bridge.
During fabric provisioning, the system requires a VLAN number to be used as the infrastructure VLAN. This VLAN is used for control communication as a reserved overlay VLAN between the fabric nodes (leaf, spine, and APIC controllers) to bring up the fabric. This VLAN is hard coded on the fabric nodes.
How is BD different from VLAN?
The BD-VLAN connects different local FD-VLANs to a single bridge domain, and is used on the Broadcom ASIC to determine the Layer 2 broadcast domain. If for example two different access_enc VLANs have the same BDVlan ID it means they belong to two EPGs that are part of the same BD.
Bridge Group BVI on FTD - YouTube
- Go to Administration.
- Click on Management.
- In the Working Mode section select Bridged Only.
- Click Save Settings.