GigaSMART Header Addition

Required License: Header Stripping

GigaSMART operations with an Add Header selected can add VLAN tags to packets. This operation is useful in the following situations:

• Differentiating stripped packets from non-stripped packets on common IP ranges (for example,10.x.x.x; 192.168.x.x).
• Removing an arbitrary-length MPLS label stack and replacing it with a single, predictable, four-byte VLAN tag between the source address and ethertype field in the Layer 2 header. Many tools that are unable to parse the arbitrary length of an MPLS label stack can work with a predictable VLAN tag.

Keep in mind the following when configuring GigaSMART operations with an Add Header component:

Add VLAN Tag

You can combine Strip Header with VLAN add to help identify packets with stripped headers. This approach lets you remove an arbitrary-length MPLS label stack and replace it with a single, predictable, four-byte VLAN tag between the source address and ethertype field in the Layer 2 header. Many tools that are unable to parse the arbitrary length of an MPLS label stack can work with a predictable VLAN tag.

Packet Modifications for add_vlan

The Add Header operation makes the following modifications to a packet:

- TPID – 0x8100 (802.1Q VLAN) or 0x88A8 and 0x9100 (Q-in-Q). The two-byte ethertype originally present in the Ethernet header is moved past the new VLAN header to identify the original Layer 3 header.
- CFI – 0
- Priority – 0
- VLAN ID – User-provided value in the VLAN field of an Add Header GigaSMART Operation.

Refer to How to Handle Q-in-Q Packets in Maps for TPID.

CRCs Recalculated

The GigaVUE H Series node automatically recalculates and applies correct CRC checksums based on the new packet length after the header is stripped.

Viewing Statistics

Use GS Operations Statistics page to see statistics related to ongoing GigaSMART operations. Refer to View GigaSMART Statistics for more information.

Combine with Other Components

You can combine the Add Header component with other GigaSMART components in a single operation. Refer to How to Combine GigaSMART Operations for details on the combinations of GigaSMART operations. Refer to Order of GigaSMART Operations for information on the order in which components of a single GigaSMART operation are applied.

GigaSMART Engine Ports

Header addition operations can be assigned to GigaSMART groups consisting of multiple engine ports. Refer to Groups of GigaSMART Engine Ports for details.