GigaSMART Traffic Performance Enhancement

This section explains about :

Flow Masking helps to identify flows, by selecting the portion of the packet for flow identification. The flow mask consists of an offset and a length, in bytes. Use the offset to specify the number of bytes from the beginning of the packet to the start of the mask within the packet. Use the length to specify the number of bytes, following the offset, to mask within the packet. The length identifies the traffic flow. Both the offset and the length are variable; however, the offset plus the length cannot be greater than 112 bytes. A default mask is provided with an offset of 14 bytes and a length of 28 bytes.

The GigaSMART encapsulated traffic performance is enhanced by using the feature Flow Masking.

For more information about encapsulated traffic performance, refer to GigaSMART Encapsulated Traffic Performance Enhancement.

GigaSMART Traffic Performance Enhancement does not require a separate license.

The GigaSMART traffic performance enhancement provides a method to improve GigaSMART packet processing for MPLS traffic and other traffic having Layer 2 encapsulation, such as L2GRE or VNTag. This type of traffic has a header in the packet between the MAC address and the IP address. Figure 1 shows the MPLS example.

Figure 51 MPLS Header Between MAC and IP Address in Packet

The GigaSMART processor is able to identify IP flows if there is only the MAC address and no other header in the packet before the IP address or if the only header before the IP address is VLAN. Without this enhancement, the GigaSMART processor cannot identify IP flows if there are MPLS headers or Layer 2 encapsulation other than VLAN before the IP address.

Most of theGigaSMARTfeatures require packets belonging to the same flow connection to be processed in the correct order. The processor uses the IP addresses and protocol to identify a traffic flow. When packets belonging to the same flow are identified, GigaSMART process these packets in a sequential manner. GigaSMART process all the encapsulated packets one at a time sequentially even though they belong to different traffic flows (different IP address pair).

Performance is impacted if the GigaSMART processor cannot use the IP source and destination (ipsrc, ipdst) to identify flows. This enhancement provides another method to identify flows. Using a flow mask, you select the portion of the packet for flow identification.

To access GigaSMART within GigaVUE‑FM, access a device that has been added to GigaVUE‑FM from the GigaVUE‑FM interface. GigaSMART appears in the navigation pane of the device view on supported devices. Refer to the Access GigaSMART from GigaVUE‑FM for details.

To configure the MPLS traffic performance enhancement, do the following:

1.   From the device view, select GigaSMART > GigaSMART Group > GigaSMART Groups.
2. Click New to create a new GigaSMART group or Edit to modify an existing one.
3. Go to Flow Mask under GigaSMART Parameters and select Enable.
4. Enter the offset and length in the Offset (bytes) and Length (bytes) fields.

If you do not enter any values in these fields, the default offset and length is used.

5. Click Save.

Refer to the following sections for examples:

■   Flow Masking Example 1
■   Flow Masking Example 2

In Example 1 packets are expected to have two MPLS labels before the IP header, and no VLAN tag between the MAC and MPLS headers. IP addresses will be used to identify the flows.

The offset will be the sum of the following: 14 bytes for the MAC address + 8 bytes for the MPLS headers +12 bytes offset from the beginning of the IP header = 34 bytes.

The length will be the sum of the following: 4 bytes for ipsrc + 4 bytes for ipdst = 8 bytes.

To access GigaSMART within GigaVUE‑FM, access a device that has been added to GigaVUE‑FM from the GigaVUE‑FM interface. GigaSMART appears in the navigation pane of the device view on supported devices. Refer to the Access GigaSMART from GigaVUE‑FM for details.

To configure Example 1, do the following:

1.   From the device view, select GigaSMART > GigaSMART Groups > GigaSMART Groups.
2. Click New to create a new GigaSMART Group or Edit to modify an exiting one.
3. Under GigaSMART Parameters, go to Flow Mask and select Enable.
4. Enter 34 in the Offset (bytes) field and 8 in the Length (bytes) field as shown in the following figure

5. Click Save.

In Example 2, packets are expected to have one VLAN tag and two MPLS labels before the IP header. IP addresses will be used to identify the flows.

The offset will be the sum of the following: 14 bytes for the MAC address + 4 bytes for the VLAN tag + 8 bytes for the MPLS headers +12 bytes offset from the beginning of the IP header = 38 bytes.

The length will be the sum of the following: 4 bytes for ipsrc + 4 bytes for ipdst = 8 bytes.

To access GigaSMART within GigaVUE‑FM, access a device that has been added to GigaVUE‑FM from the GigaVUE‑FM interface. GigaSMART appears in the navigation pane of the device view on supported devices. Refer to the Access GigaSMART from GigaVUE‑FM for details.

To configure Example 2, do the following:

To configure Example 1, do the following:

1.   From the device view, select GigaSMART > GS Groups > GS Groups.
2. Click New to create a new GigaSMART Group or Edit to modify an exiting one.
3. Click Enable under GS Params Flow Mask.
4. Enter 38 in the Offset (bytes) field and 8 in the Length (bytes) field as shown in the following figure.

5. Click Save.