• Flow Label (20 bits)• Payload Length (16 bits)• Next Header (8 bits)• Hop Limit (8 bits)• Source Address (128 bits)• Destination Address (128 bits)IPv6 provides for extension headers. Extension headers are used only if necessary. There can be no extension headers, one extensionheader or more than one extension header in an IPv6 packet. Extension headers are defined in the Next Header field of the preceding IPv6header.Longest Prefix Match (LPM) Table and IPv6 /65 – /128supportTwo partitions are available.• Partition I with IPv6 /65 – /128 route prefix. Doesn’t support IPv4 entries in the current release.• Partition II with IPv6 0/0 – /64 route prefix and IPv4 0/0 -0/32 route prefix entries.• Number of entries in Partition II will be reduced based on the number of entries configured in Partition I.• Partitioning will be applied well before the system initialization. This will be done using the NVRAM.• Dell Networking OS provides CLI for enabling the partition. Configuration will be stored in NVRAM when the operator saves theconfiguration.• Partition will take effect only after the switch reboot. During the reboot Dell Networking OS reads the partition configuration fromNVRAM and uses the same for partitioning the LPM.• A command has been introduced to partition the LPM to support provisioning of IPv6 /65 to /128 route prefixes.To support /65 – /128 IPv6 route prefix entries, Dell Networking OS needs to be programmed with /65 - /128 bit IPv6 support. Thenumber of entries as well needs to be explicitly programmed. This number can be1K, 2K, or 3K granularity.On the system, for IPv6 /65 to /128 will consume the same storage banks which is used by the L3_DEFIP table. Once the IPv6 128 bit isenabled, number of entries in L3_DEFIP will be reduced.LPM partitioning will take effect after reboot of the box. This is because the SDK does the LPM partitioning during the chip initialization.The longest prefix match (LPM) table on the system supports different types of prefixes for IPv6 and IPv4. The route table, also called theLPM table, is divided into the following three logical tables:1 IPv4 32-bit LPM table (Holds IPv4 Prefixes)2 IPv6 64-bit LPM table (Holds IPv6 Prefixes less than /65 Prefix Length)3 IPv6 128-bit LPM table (Holds IPv6 Prefixes greater than /64 Prefix Length)The LPM table, which is 8K in size, is a dedicated table. It comprises eight ternary content addressable memory (CAM) blocks, with eachblock being 1K in size. The table can contain 16KIPv4 route entries or 8K IPv6 route entries (less than /65 prefix-length) or 3K IPv6 routeentries (greater than /64 prefix-length). You can configure the LPM table with one of the following partitions to support the IPv4 and IPv6prefix route entries:• Partition 1: IPv6 128-bit LPM entries can be stored in this partition. IPv4 and 64-bit IPv6 entries cannot be saved in this partition.• Partition 2: IPv4 LPM and 64-bit IPv6 LPM entries can be stored in this partition.IPv6 Routing 413
