Service Manual

● Prefix Renumbering — Useful in transparent renumbering of hosts in the network when an organization changes its
service provider.
NOTE: As an alternative to stateless autoconfiguration, network hosts can obtain their IPv6 addresses using the dynamic
host control protocol (DHCP) servers via stateful auto-configuration.
NOTE: Dell EMC Networking OS provides the flexibility to add prefixes on Router Advertisements (RA) to advertise
responses to Router Solicitations (RS). By default, RA response messages are sent when an RS message is received.
Dell EMC Networking OS manipulation of IPv6 stateless autoconfiguration supports the router side only. Neighbor discovery
(ND) messages are advertised so the neighbor can use this information to auto-configure its address. However, received ND
messages are not used to create an IPv6 address.
NOTE: Inconsistencies in router advertisement values between routers are logged per RFC 4861. The values checked for
consistency include:
● Cur Hop limit
● M and O flags
● Reachable time
● Retrans timer
● MTU options
● Preferred and valid lifetime values for the same prefix
Only management ports support stateless auto-configuration as a host.
The router redirect functionality in the neighbor discovery protocol (NDP) is similar to IPv4 router redirect messages. NDP uses
ICMPv6 redirect messages (Type 137) to inform nodes that a better router exists on the link.
IPv6 Headers
The IPv6 header has a fixed length of 40 bytes. This fixed length provides 16 bytes each for source and destination information
and 8 bytes for general header information.
The IPv6 header includes the following fields:
● Version (4 bits)
● Traffic Class (8 bits)
● 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
extension header or more than one extension header in an IPv6 packet. Extension headers are defined in the Next Header field
of the preceding IPv6 header.
Longest Prefix Match (LPM) Table and IPv6 /65 – /128 support
Two 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 EMC Networking OS provides CLI for enabling the partition. Configuration will be stored in NVRAM when the operator
saves the configuration.
● Partition will take effect only after the switch reboot. During the reboot Dell EMC Networking OS reads the partition
configuration from NVRAM and uses the same for partitioning the LPM.
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IPv6 Routing