MN.00273.E - 004 69
VLAN rewriting
VLAN rewriting is a feature available on radio side that allows to rewrite the VID of C-TAG of the packet
received (uplink side) or sent (downlink side) by the switch.
On uplink side (packets received on LAN interface by the switch and sent to the radio) the VID can be re-
written on the basis of the following criteria:
- LAN port + C-VID: new values of C-VID to be written into the packet can be configured on the basis
of its original C-VID and the LAN port where it has been received.
- LAN port + C-VID + priority: new values of C-VID to be written into the packet can be configured
on the basis of its original C-VID + priority and the LAN port where it has been received.
On uplink side it is possible to configure for all the LAN ports up to 64 LAN port + C-VID or LAN port + C-
VID + priority criteria.
On downlink side (packets received on radio side and sent by the switch on the LAN interface):
• the VID can be rewritten on the basis of the C-VID of the received packet. I.e., new values of C-
VID to be written into the packet can be configured on the basis of its original C_VID. It is possible
to configure up to 64 C-VID criteria in downlink, independently by the uplink configuration.
• C-VID can be removed selectively. It is possible to select the C-VID, enable the option “Removed”
and select the Output interface. In other words on downlink side it is possible to select the C-VID
to be remove and the correspondent Output LAN.
Selective QinQ based on VLAN and IEEE 802.1p priority
VLAN staking (also named QinQ) is a feature that allows an Ethernet frame to include more than one IEEE
802.1Q TAG. The scope of VLAN staking is to differentiate the traffic at different levels when the packets
must cross networks managed by different entities.
The SIAE switch radio supports the Vlan staking. Once a packet enters into the radio it is possible to add
a new IEEE 802.1Q TAG. The VID of the new TAG can be set based on different criteria:
- Ingress port of the packet
- C-VID and priority of the packet when received on the ingress port
The new TAG is added to the packet as a S-TAG. The Ethertype field of the TAG can be set either to stand-
ard values (0x88A8, 0x9100, 0x9200, 0x9300) or to any other custom values.
Packet Compression
The SIAE switch provides header packet compression. This feature allows to compress the packet header
by transmitting over the radio link proprietary labels in place of long and repetitive header field.
Multi-layer Packet Compression supports the following protocols: Ethernet, MPLS, IPv4/IPv6, UDP and RTP
and LTE S1 interface tunnelling. This latter cover the case of LTE eNodeB backhauling on S1 interface,
where the eUE traffic (either IPv4 or IPv6) is enveloped into a GTP-U tunnel. The Header compressed in
this case includes (IPv4+UDP+GTP-U of the S1 interface)+(IPv4/IPv6+UDP+RTP of the eUE traffic inserted
into the tunnel).
When enabled, the user can select which header have to be compressed considering the following maxi-
mum limits:
• the total header field size cannot exceed 124 bytes
• the total header field size after internal coding cannot exceed 118 bytes. the internal coding is re-
quired by SIAE switch in order to perform the compression task.
In Fig.24
are detailed the different header fields that can be selected with their weight in terms of header
field size and header field size after internal coding.
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