Operation Manual – VLAN-VPNH3C S3100 Series Ethernet Switches Chapter 3 VLAN Mapping Configuration3-1Chapter 3 VLAN Mapping ConfigurationNote:This chapter is only applicable to S3100-EI series switches.3.1 VLAN Mapping Overview3.1.1 Introduction to VLAN MappingThe VLAN mapping function can replace the private network VLAN tag of a customerpacket with a public network VLAN tag, so that the customer packet can be transmittedwithin the public network in a way conforming to the public network layout. When thepacket reaches the peer customer network, the VLAN tag of the packet is restored tothe previous private network VLAN tag. In this way, the packet is transmitted to thedestination properly.With the VLAN mapping function enabled, when the switch receives a packet taggedwith a network VLAN tag, it looks up the mapping rules configured for the matchedVLAN tag and then replaces the existing VLAN tag with the corresponding one (if thematched mapping rule exists).Figure 3-1 shows the structure of a packet tagged with a private network VLAN tag.Figure 3-1 The structure of a packet tagged with a private network VLAN tagFigure 3-2 shows the structure of a packet after VLAN tag replacement.Figure 3-2 The structure of a packet tagged with a public network VLAN tagDifferent from VLAN VPN and selective QinQ, the VLAN mapping function does notcause a packet to carry multiple VLAN tags. A packet is transmitted with only one VLANtag. Therefore, you need to make sure the private network VLAN tags can be restoredbefore customer packets enter the destination private network for customer packets tobe transmitted properly.
