The number is arbitrary it has nothing to do with the VLANs that will be processed by this particular Service Instance The "ethernet" keyword is always used. We only need to enable VLAN tag processing and let the Service Instance figure out what to do with the frame. Because of this we do not want to allow any globally configured VLANs across this trunk interface. Furthermore Service Instance interfaces do not do any MAC learning (except through a bridge-domain VLAN interface, which is discussed later). VLAN tags received on Service Instance interfaces have no direct relationship to VLANs configured on the switch. These lines tell the interface that we need to process 802.1q tags as a trunk interface should, however we will not actually pass any VLANs through this interface. Now, let's break down each piece of this configuration. Xconnect 192.168.1.1 33 encapsulation mpls Let's take a look at a sample EVC configuration. Within the EVC we define what action we wish to do with that frame. For example we could allocate VLAN 10 to different customers on every switchport and forward each customer's traffic across different MPLS Pseudowires, but never actually configure VLAN 10 globally! How It Works (Ingress)Īs an 802.1q tagged frame enters an interface that has been configured with an EVC we will determine which EVC it is classified into based on the tags on the frame. Now, with EVCs we can separate these concepts the VLAN tag is used for classification and the Service Instance defines the forwarding action. Traditionally the VLAN tag defined both classification (which VLAN) and forwarding (which CAM table to do a MAC lookup in). Enter EVCsĮthernet Virtual Circuits (EVCs) allow us to leverage existing 802.1q VLAN tags in a brand new way. In modern provider and cloud environments there is a need to scale beyond these limitations.
Adtran show mac address table for mac#
Furthermore switches have a finite amount of CAM space for MAC Learning limiting the number of hosts we can support. Since the 802.1q VLAN tag is only 12-bits wide we can only configure a maximum of 4096 VLANs. The challenge with this is that it requires us to use finite resources, perhaps without reason. To do this we require the switch to do two things:
The switch needs to determine which MAC Address table to look in for a forwarding decision.
On traditional switches whenever we have a trunk interface we use the VLAN tag to demultiplex the VLANs.
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