Dell MX5108n OS10 Enterprise Edition User Guide for PowerEdge MX IO Modules Re - Page 335

Neighbor discovery

Page 335 highlights

Stateless autoconfiguration of IPv6 addresses is performed using: Prefix advertisement Routers use router advertisement messages to advertise the network prefix. Hosts append their interface-identifier MAC address to generate a valid IPv6 address. Duplicate address detection An IPv6 host node checks whether that address is used anywhere on the network using this mechanism before configuring its IPv6 address. Prefix renumbering Transparent renumbering of hosts in the network when an organization changes its service provider. IPv6 provides the flexibility to add prefixes on router advertisements in response to a router solicitation (RS). By default, RA response messages are sent when an RS message is received. The system manipulation of IPv6 stateless autoconfiguration supports the router side only. Neighbor Discovery (ND) messages advertise so the neighbor can use the information to auto-configure its address. Received ND messages are not used to create an IPv6 address. Inconsistencies in router advertisement values between routers are logged. The values checked for consistency include: • Current hop limit • M and O flags • Reachable time • Retransmission timer • MTU options • Preferred and valid lifetime values for the same prefix 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. Neighbor discovery The IPv6 Neighbor Discovery protocol (NDP) determines if neighboring IPv6 devices are reachable and receives the IPv6 addresses of IPv6 devices on local links. Using the link-layer and global prefixes of neighbor addresses, OS10 performs stateless autoconfiguration of IPv6 addresses on interfaces. ICMPv6 Router Advertisement messages advertise the IPv6 addresses of IPv6-enabled interfaces and allow a router to learn of any address changes in IPv6 neighbors. By default, router advertisements are disabled on an interface. Prerequisites To enable RA messages, the switch must be in Router mode with IPv6 forwarding enabled and stateless autoconfiguration disabled (no ipv6 address autoconfig command). Enable router advertisement messages 1 Enable IPv6 neighbor discovery and sending ICMPv6 RA messages in Interface mode. ipv6 nd send-ra 2 (Optional) Configure IPv6 neighbor discovery options in Interface mode. • ipv6 nd hop-limit hops - (Optional) Sets the hop limit advertised in RA messages and included in IPv6 data packets sent by the router (0 to 255; default 64). 0 indicates that no hop limit is specified by the router. • ipv6 nd managed-config-flag - (Optional) Sent in RA messages to tell hosts to use stateful address autoconfiguration, such as DHCPv6, to obtain IPv6 addresses. • ipv6 nd max-ra-interval seconds - (Optional) Sets the maximum time interval for sending RA messages (4 to 1800 seconds; default 600). • ipv6 nd mtu number - (Optional) Sets the maximum transmission unit (MTU) used in RA messages on the link (1280 to 65535 bytes; default 1500). By default, no MTU setting is included in RA messages. • ipv6 nd other-config-flag - (Optional) Tells hosts to use stateful autoconfiguration to obtain nonaddress-related information. Layer 3 335

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Stateless
autoconfiguration
of IPv6 addresses is performed using:
Prefix
advertisement
Routers use router advertisement messages to advertise the network
prefix.
Hosts append their
interface-identifier
MAC address to generate a valid IPv6 address.
Duplicate address
detection
An IPv6 host node checks whether that address is used anywhere on the network using this mechanism before
configuring
its IPv6 address.
Prefix
renumbering
Transparent renumbering of hosts in the network when an organization changes its service provider.
IPv6 provides the
flexibility
to add
prefixes
on router advertisements in response to a router solicitation (RS). By default, RA response
messages are sent when an RS message is received. The system manipulation of IPv6 stateless
autoconfiguration
supports the router side
only. Neighbor Discovery (ND) messages advertise so the neighbor can use the information to
auto-configure
its address. Received ND
messages are not used to create an IPv6 address.
Inconsistencies in router advertisement values between routers are logged. The values checked for consistency include:
Current hop limit
M and O
flags
Reachable time
Retransmission timer
MTU options
Preferred and valid lifetime values for the same
prefix
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.
Neighbor discovery
The IPv6 Neighbor Discovery protocol (NDP) determines if neighboring IPv6 devices are reachable and receives the IPv6 addresses of
IPv6 devices on local links. Using the link-layer and global
prefixes
of neighbor addresses, OS10 performs stateless
autoconfiguration
of
IPv6 addresses on interfaces.
ICMPv6 Router Advertisement messages advertise the IPv6 addresses of IPv6-enabled interfaces and allow a router to learn of any
address changes in IPv6 neighbors. By default, router advertisements are disabled on an interface.
Prerequisites
To enable RA messages, the switch must be in Router mode with IPv6 forwarding enabled and stateless
autoconfiguration
disabled (
no
ipv6 address autoconfig
command).
Enable router advertisement messages
1
Enable IPv6 neighbor discovery and sending ICMPv6 RA messages in Interface mode.
ipv6 nd send-ra
2
(Optional)
Configure
IPv6 neighbor discovery options in Interface mode.
ipv6 nd hop-limit
hops
— (Optional) Sets the hop limit advertised in RA messages and included in IPv6 data packets
sent by the router (0 to 255; default 64).
0
indicates that no hop limit is
specified
by the router.
ipv6 nd managed-config-flag
— (Optional) Sent in RA messages to tell hosts to use stateful address
autoconfiguration,
such as DHCPv6, to obtain IPv6 addresses.
ipv6 nd max-ra-interval
seconds
— (Optional) Sets the maximum time interval for sending RA messages (4 to 1800
seconds; default 600).
ipv6 nd mtu
number
— (Optional) Sets the maximum transmission unit (MTU) used in RA messages on the link (1280 to
65535 bytes; default 1500). By default, no MTU setting is included in RA messages.
ipv6 nd other-config-flag
— (Optional) Tells hosts to use stateful
autoconfiguration
to obtain nonaddress-related
information.
Layer 3
335