Advanced Hashing

Both regular GigaStream and controlled GigaStream use advanced hashing, which lets you select the criteria on which the hash is based, such as source and destination IP address, source and destination MAC address, source and destination port, and protocol.

GigaVUE‑OS nodes distribute traffic between the ports in a GigaStream based on the hashing criteria configured using the Advanced Hash Settings page for the selected line card or chassis. GigaStream hashing is applicable for the following port types:

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Tool port

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Hybrid port

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Circuit port

To open the Advanced Hash Settings page, select Ports > Port Groups > GigaStream and click Advanced Hash Settings. (For more details, refer to Advanced Hash Settings.) On the GigaVUE nodes, GigaStream hashing is per chassis, not per line card.

The Advanced Hash Settings let you select the different packet criteria used to send matching flows to the same destination port within a GigaStream.

By default, the GigaVUE HC Series node hashes traffic based on source and destination IP addresses, IP protocol, and source and destination ports.

How to Change Advanced Hash Criteria

You can select the criteria for the advanced hash algorithm by using Advanced Hash Settings. The advanced hash method you specify is used for all GigaStream in place on the specified line card or chassis.

Advanced Hash Settings

The Advanced Hash Settings page is where criteria for the advanced hash algorithm is set. To open the page, select Ports > Port Groups > GigaStream and click Advanced Hash Settings.

The following table describes the fields in the Advanced Hashing Settings page.

Field

Description

Box

Identifies chassis to which the advanced algorithm will be applied.

Slot

Identifies the line card to which the advanced hash algorithm will apply. Each line card in certain GigaVUE HC Series nodes has its own individual advanced hash algorithm.

On GigaVUE‑HC1, GigaVUE‑HC2, and GigaVUE‑HC3, GigaStream hashing is per chassis, not per line card. For example, the slot field will only show cc1 when configuring an GigaVUE‑HC2.

Default

Sets the advanced hash algorithm to its default settings. By default, the advanced hash algorithm includes source/destination IPv4/IPv6 addresses and ports.

Custom

Clears the field from the advanced has and allows you to select specific own criteria.

All

Selects all criteria.

None

Clears all fields from the advanced hash.

IPv4

This area of the page lets you select the following criteria:

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IPv4 Source Address—Adds IPv4 source IP

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IPv4 Destination Address—Adds IPv4 destination IP

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IPv4 Protocol—Adds IPv4 protocol

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IPv4 Source Port—Adds IPv4 source port

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IPv4 Destination Port—Adds IPv4 destination port

IPv6

This area of the page lets you select the following criteria:

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IPv6 Source Address—Adds IPv6 source IP

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IPv6 Destination Address—Adds IPv6 destination IP

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IPv6 Next Header—Adds IPv6 next header field.

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IPv6 Source Port—Adds IPv6 source port

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IPv6 Destination Port—Adds IPv6 destination port

Layer2

This area of the page lets you select the following criteria:

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Source MAC Address—Adds L2 source MAC

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Destination MAC Address—Adds L2 destination MAC

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EtherType—Adds L2 ethertype field.

MPLS

This area of the page lets you select the following criteria:

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MPLS Hash—Adds MPLS labels (up to three)

GTP TEID

This area of the page lets you select the following criteria:

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GTP TEID—Adds GTP tunnel endpoint identifier

Ingress Port

This area of the page lets you select the following criteria:

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Ingress Ports—Adds ingress port

Advanced Hash Examples

The following are some different advanced hash examples. Note that the advanced hash method usually combines multiple criteria.

The example in 1 Advanced Hash with IPv4 Source and Destination Addresses sets a Custom advanced hash method for slot 3 in box ID 5 that distributes traffic based on matching IPv4 source and destination addresses.

Advanced Hash with IPv4 Source and Destination Addresses

The example in 2 sets the advanced hash for slot cc1 in box ID 2 to the Default criteria.

Advanced Hash Default Criteria

The example in 3 Advanced Hash with Source and Destination MAC Address sets a Custom advanced hash for slot 5 in box ID 5 that distributes traffic based on matching source and destination MAC addresses.

Advanced Hash with Source and Destination MAC Address

Hashing Behavior

Table 4: Hashing Behavior Based on Hash Criteria Field Combinations shows the possible hash criteria field combinations and the corresponding hashing behavior based on packet type for advanced hashing for non-MPLS packets. (Refer to Table 5: Hashing Behavior Based on Hash Criteria Field Combinations for MPLS packets.)

Table 4: Hashing Behavior Based on Hash Criteria Field Combinations

Note: No hash means that the packets will be sent to the first port in the GigaStream.

Notes and Considerations for Advanced Hashing

Refer to the following notes and considerations for advanced hashing:

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With symmetric hashing, packets with their source and destination IP addresses and Layer 4 (L4) ports interchanged will go to the same GigaStream port. It is recommended to enable source and destination IPv4 or IPv6 pairs and L4 source and destination ports.

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Symmetric hashing is enabled for all GigaStream on all GigaVUE H Series and TA Series nodes (except TA25 and TA400).

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For non-MPLS IPv4 and IPv6 packets, the hashing is fixed to the following 3-tuple: ipsrc, ipdst, and protocol or ip6src, ip6dst, and protocol. All other traffic follows the advanced hash settings.

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ASICs used in Gigamon devices do not support hashing of the IP header fields when there is a PPPOE header. Only Layer 2 (L2) fields can be used for such packets.

Advanced Hashing with MPLS

Starting in software version 5.1, GigaStream MPLS hashing adds the ability to hash on MPLS labels as well as the following IP address fields inside an MPLS tunnel: ipsrc, ipdst, ip6src, and ip6dst.

Advanced hashing with MPLS is supported on all GigaVUE H Series and TA Series nodes.

Use the Advanced Hash Settings to specify MPLS, which can detect up to three MPLS labels. Packets with one to three MPLS labels can be hashed, along with IP address fields, if present. If a packet has more than three MPLS labels, IP address fields after the third MPLS label cannot be hashed. Refer to Hashing Behavior Based on Hash Criteria Field Combinations for details of the hashing behavior.

MPLS labels will be used as part of the GigaStream hash criteria if the MPLS field is configured and the packet has EtherType 0x8847.

MPLS hashing applies to the following:

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regular GigaStream

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controlled GigaStream

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stack GigaStream

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inline tool groups

Table 5: Hashing Behavior Based on Hash Criteria Field Combinations shows the possible hash criteria field combinations and the corresponding hashing behavior based on packet type for advanced hashing with MPLS packets. (Refer to Table 4: Hashing Behavior Based on Hash Criteria Field Combinations for non-MPLS packets.)

Table 5: Hashing Behavior Based on Hash Criteria Field Combinations

Hash Criteria Fields	Packet Type	Hashing Behavior
IPv4 Source Address,IPv4 Destination Address	MAC + Label1 + Label2 + Label3 + IP + L4 + Payload	Hash on IP
Source MAC Address,Destination MAC Address	outer MAC + Label1 + Label2 + Label3 + inner MAC + IP + L4 + Payload	Hash on outer MAC
Source MAC Address,Destination MAC Address	MAC + Label1 + Label2 + Label3 + IP + L4 + Payload	Hash on MAC
MPLS Hash	MAC + Label1 + Label2 + Label3 + IP + L4 + Payload	Hash on MPLS Label1, Label2, Label3
MPLS Hash	MAC + Label1 + Label2 + IP + L4 + Payload	Hash on MPLS Label1, Label 2
MPLS Hash	MAC + Label1 + IP + L4 + Payload	Hash on MPLS Label1
MPLS Hash, EtherType, IPv4 Protocol	MAC + Label1 + Label2 + Label3 + Label4 + IP + L4 + Payload	Hash on MPLS Label1, Label2, Label3
MPLS Hash,IPv4 Source Address,IPv4 Destination Address	MAC + MPLS Label1 + IP + L4 + Payload	Hash on MPLS Label1, IPv4 Source Address, IPv4 Destination Address
MPLS Hash,IPv4 Source Address,IPv4 Destination Address	MAC + Label1 + Label2 + IP + L4 + Payload	Hash on MPLS Label1, Label2, IPv4 Source Address, IPv4 Destination Address
MPLS Hash,IPv4 Source Address,IPv4 Destination Address	MAC + Label1 + Label2 + Label3 + IP + L4 + Payload	Hash on MPLS Label1, Label2, Label3, IPv4 Source Address, IPv4 Destination Address
MPLS Hash,IPv4 Source Address,IPv4 Destination Address	MAC + Label1 + Label2 + Label3 + Label4 + IP + L4 + Payload	Hash on MPLS Label1, Label2, Label3
MPLS Hash,IPv4 Source Address,IPv4 Destination Address	MAC + MPLS Label1 + MAC + IP + L4 + Payload	Hash on MPLS Label1
MPLS Hash,IPv4 Source Address,IPv4 Destination Address	MAC + Label1 + Label2 + MAC + IP + L4 + Payload	Hash on MPLS Label1, Label2
MPLS Hash,IPv4 Source Address,IPv4 Destination Address	MAC + Label1 + Label2 + Label3 + MAC + IP + L4 + Payload	Hash on MPLS Label1, Label2, Label3
MPLS Hash,Source MAC Address,Destination MAC Address	MAC + Label1 + Label2 + Label3 + IP + L4 + Payload	Hash on MPLS Label1, Label2, Label3
MPLS Hash,IPv4 Source Port,IPv4 Destination Port	MAC + Label1 + Label2 + Label3 + Label4 + IP + L4 + Payload	Hash on MPLS Label1, Label2, Label3
IPv4 Source Port,IPv4 Destination Port	MAC + Label1 + Label2 + Label3 + IP + L4 + Payload	No Hash

NOTES:

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No hash means that the packets will be sent to the first port in the GigaStream.

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If an MPLS packet has a router alert label as one of its labels, the router alert label is skipped and the other available labels are used for hashing. For example, if a packet has four labels and the second label is the router alert, the first, third, and fourth labels are used for hashing.

Advanced Hashing with GTP TEID

Starting in software version 5.2, GigaStream GTP TEID hashing adds the ability to hash on GTP tunnel endpoint identifiers (TEIDs). GPRS Tunneling Protocol (GTP) is an IP/UDP-based protocol for mobile data.

The TEID field in a GTP header is a unique identifier for mobile subscribers and is used to multiplex different connections on the same GTP tunnel. Use GTP TEID advanced hashing to load balance GTP packets across all GigaStream ports.

Advanced hashing with GTP TEID is supported on GigaVUE H Series and TA Series nodes, with the following distinctions:

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The following nodes are supported: GigaVUE‑HC1, GigaVUE‑HC1-Plus, GigaVUE‑HC2 (with control card version 1 or 2), GigaVUE‑HC3 (with control card version 1 or 2), GigaVUE‑TA25, GigaVUE‑TA25E, GigaVUE-TA40, GigaVUE-TA100, GigaVUE‑TA200, GigaVUE‑TA200E, and GigaVUE‑TA400.

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The following nodes are not supported: GigaVUE-TA10.

Use the Advanced Hash Settings to specify the GTP TEID field. It must be specified with one of the port source and destination pairs: either IPv4 Source Port and IPv4 Destination Port for IPv4 or IPv6 Source Port and IPv6 Destination Port for IPv6.

When the GTP TEID field is configured, GTP packets will use it for hashing along with configured IP fields, instead of the Layer 4 (L4) source and destination for GTP packets. The hashing for all non-GTP packets will be based on L4 source and destination port.

GTP TEID hashing is supported only for GTP-User packets, version 1 (V1), with L4 source and destination port 2152. The hashing functionality works only for non-fragmented packets.

Refer to Hashing Behavior Based on Hash Criteria Fields: GTP TEID for details of the hashing behavior.

GTP TEID hashing applies to the following:

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regular GigaStream

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controlled GigaStream

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stack GigaStream (except GigaVUE‑HC2 and GigaVUE‑HC3)

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inline tool groups

Note: GTP TEID hashing is not supported for stack GigaStream on GigaVUE‑HC2 and GigaVUE‑HC3 in this software version due to the 3-tuple limitation listed in Notes and Considerations for Advanced Hashing.

Table 6: Hashing Behavior Based on Hash Criteria Fields: GTP TEID shows the possible hash criteria field combinations and the corresponding hashing behavior based on packet type for advanced hashing with GTP packets.

Table 6: Hashing Behavior Based on Hash Criteria Fields: GTP TEID

Hash Criteria Fields	Packet Type	Hashing Behavior
IPv4 Source Address,IPv4 Destination Address,IPv4 Source Port,IPv4 Destination Port	MAC + IP + L4 + Payload	Hash on IPv4 Source Address,IPv4 Destination Address,IPv4 Source Port,IPv4 Destination Port
IPv4 Source Address,IPv4 Destination Address,IPv4 Source Port,IPv4 Destination Port,GTP TEID	MAC + IP + L4 + GTP + Payload	Hash on IPv4 Source Address,IPv4 Destination Address, GTP TEID
IPv4 Source Address,IPv4 Destination Address,IPv4 Source Port,IPv4 Destination Port,GTP TEID	MAC + IP + L4 + Payload	Hash on IPv4 Source Address,IPv4 Destination Address,IPv4 Source Port,IPv4 Destination Port
IPv6 Source Address,IPv6 Destination Address,IPv6 Source Port,IPv6 Destination Port	MAC + IP + L4 + Payload	Hash on IPv6 Source Address,IPv6 Destination Address,IPv6 Source Port,IPv6 Destination Port
IPv6 Source Address,IPv6 Destination Address,IPv6 Source Port,IPv6 Destination Port,GTP TEID	MAC + IP + L4 + GTP + Payload	Hash on IPv6 Source Address,IPv6 Destination Address, GTP TEID
IPv6 Source Address,IPv6 Destination Address,IPv6 Source Port,IPv6 Destination Port,GTP TEID	MAC + IP + L4 + Payload	Hash on IPv6 Source Address,IPv6 Destination Address,IPv6 Source Port,IPv6 Destination Port

Packet Distribution and the Advanced Hash Algorithm

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When an IPv4 Fragmentation map rule is used to send traffic to an advanced hash tool GigaStream, all fragments are consolidated to a single port within the GigaStream.

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Packets with multiple VLAN tags (such as Q-in-Q) will experience uneven traffic distribution. For this traffic, GigaSMART load balancing is recommended.