Hash Key Type 14: 3-Tuple GTPv0

Napatech Link-Capture™ Software Features
Platform
Napatech SmartNIC
Content Type
Feature Description
Capture Software Version
Link™ Capture Software 12.13

Hash key data

Hash key type 14 is a 3-tuple where the hash key data is the contents of these packet header fields:

  • 32-bit IPv4 / 128-bit IPv6 source address
  • 32-bit IPv4 / 128-bit IPv6 destination address
  • 16-bit GTPv0 flow label

For IPv4 packets, hash key data word 0 is always the IPv4 source address, and hash key data word 4 is always the IPv4 destination address. For IPv6 packets, hash key data words 0 – 3 are always the IPv6 source address, and hash key data words 4 – 7 are always the IPv6 destination address. This means that frames sent from IP address A to IP address B will generate a hash value different from frames sent from IP address B to IP address A (if address A and B are different).

The GTPv0 flow label is always placed in the lower 16 bits of hash key data word 8. The rest of this word is all zeros.

For IPv4 packets, hash key data words 1 – 3, 5 – 7 and 9 are all zeros for hash key type 14. For IPv6 packets, hash key data word 9 is all zeros for hash key type 14.

Illustration for IPv4 packets

This figure illustrates hash key type 14 for IPv4 packets.

3 - tuple GTPv 0 hash key GTPv 0 packet header IPv 4 packet header Ver . & IHL T o S Total l ength Identification F Fragment offset TTL Prot . Header checksum Source address Destination address Options 0 4 8 12 16 20 0 4 8 16 - bit GTPv 0 flow label Hash key data word Flags Type Total length Sequence Payload 16 - bit all zeros Flow label Reserved TID 12 20 32 - bit IPv 4 source address 32 - bit IPv 4 destination address 0 1 2 0 0 0 0 0 0 3 4 5 6 7 8

Illustration for IPv6 packets

This figure illustrates hash key type 14 for IPv6 packets.

3 - tuple GTPv 0 hash key GTPv 0 packet header 0 4 8 16 - bit GTPv 0 flow label Hash key data word Flags Type Total length Sequence Payload 16 - bit all zeros Flow label Reserved TID 12 20 8 IPv 6 packet header Ver . & Pri . Flow label Length Next header Hop limit Source address Destination address 0 4 8 12 16 20 24 28 32 36 40 128 - bit IPv 6 source address 128 - bit IPv 6 destination address 0 , 1 , 2 & 3 4 , 5 , 6 & 7

Validity

Hash key type 14 is valid for frames containing an IPv4 packet or an IPv6 packet with a GTPv0 packet as payload.