Dhcpv6 Relay Agent Prefix Delegation Notification Limitations - Brocade Communications Systems FastIron SX 800 Configuration Manual

DHCPv6 Relay Agent Prefix Delegation Notification
FIGURE 17 DHCPv6 Relay Agent Prefix Delegation Notification
A route is added to the IPv6 route table on the provider edge router (PE) for the delegated prefix to be delegated to requesting routers.
The DHCP server chooses a prefix for delegation and responds with it to the CPEx. to the external network and to enable the correct
forwarding of the IPv6 packets for the delegated IPv6 prefix. Adding the delegated prefix to the IPv6 route table ensures that the unicast
Reverse Path Forwarding (uRPF) works correctly.
Since the PE is also a DHCPv6 relay agent (it relays DHCPv6 messages between the CPE and the DHCP server), it examines all
DHCPv6 messages relayed between the CPE and the DHCP server and gathers information about a delegated prefix and then manages
the advertisement of this delegated prefix to the external network.

DHCPv6 Relay Agent Prefix Delegation Notification limitations

The following limitations apply to the DHCPv6 Relay Agent Prefix Delegation Notification.
• The PD notification fails when the DHCPv6 messages between a DHCPv6 server and a DHCPv6 client containing the PD
option are not relayed via the DHCPv6 relay agent.
• If the delegated prefix is released or renewed by the client at the time when the DHCPv6 relay agent is down or rebooting, then
this release or renewal of the delegated prefix will not be detected by the relay agent. In such a condition, there could be stale
static routes in the routing table. You must clear the stale routes.
• If there is no sufficient disk space on a flash disk, then the system may not store all the delegated prefixes in the IPv6 route
table.
• The DHCPv6 PD flash operation will depend on the NTP clock synchronization. During system boot up, if the NTP is
configured, the flash operation (dhcp6_delegated_prefixes_data flash file read/write) is delayed till the NTP is synchronized. The
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FastIron Ethernet Switch Layer 3 Routing
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