H3C S9500 Series Operation Manual

Also see for S9500 Series: Operation manual Operation manual Operation manual Operation manual Operating manual

Contents

Operation Manual – VLAN-QinQH3C S9500 Series Routing Switches Chapter 5 Q-in-Q Configuration5-25.1.2 Implementation of Q-in-QQ-in-Q can be implemented on S9500 series switches in the following two ways:1) Enabling VLAN VPN feature on portsWith VLAN VPN enabled, a received packet is tagged with the default VLAN tag of theport no matter whether or not the packet carries a VLAN tag. Thus, if the packet alreadycontains a tag, it will carry two tags; otherwise, the packet will carry the default VLANtag.2) Configuring traffic classification-based nested VLANsYou can implement Q-in-Q in a more flexible way by configuring trafficclassification-based nested VLANs. You can specify to perform the following operationson packets that match specified ACL rules:z Setting the outer VLAN tagsz Modifying the outer VLAN tags5.1.3 Adjusting TPID Values of Q-in-Q PacketsTag protocol identifier (TPID) is a portion of the VLAN tag field. IEEE 802.1Q specifiesthe value of TPID to be 0x8100.The structure of the Tag field of an Ethernet frame defined by IEEE 802.1Q is asfollows:DA SA Tag Frame Load FCS6 bytes 6 bytes 4 bytes 46 ~1500 bytes 4 bytesTPID User Priority CFI VLAN ID2 bytes 3 bits 1bit 12 bitsDA SA Tag Frame Load FCS4 bytesTPID User Priority CFI VLAN ID2 bytes 3 bits 1bit 12 bitsDA SA Tag Frame Load FCS6 bytes 6 bytes 4 bytes 46 ~1500 bytes 4 bytesTPID User Priority CFI VLAN ID2 bytes 3 bits 1bit 12 bitsDA SA Tag Frame Load FCS4 bytesTPID User Priority CFI VLAN ID2 bytes 3 bits 1bit 12 bitsFigure 5-3 The structure of the Tag field of an Ethernet frameBy default, a S9500 series switch uses 0x8100 as the value of the TPID field, which isdefined by IEEE 802.1Q. But S9500 series switches can also adjust the TPID values ofQ-in-Q packets. This ensures S9500 series switches are compatible with devicescoming from other vendors even through the later use other TPID values (such as0x9100 or 0x9200) in the outer tags of Q-in-Q packets.To modify the TPID values of packets, you need to set the ports connecting to the publicnetworks to be VLAN-VPN uplink ports, whose TPID value can be configured by users.After you configure a TPID value for a VLAN-VPN uplink port, the switch substitutes thenew TPID values for those VLAN-VPN uplink ports in the outer tags carried by received