Avaya ERS 8600 series, Руководство по настройке

Страница: 49 / 420

Authentication
OSPF for IPv6 requires the IP Authentication Header and the IP Encapsulating Security
Payload for authentication and security. OSPFv3 does not support the authentication feature
from OSPFv2.
IPv6 uses the 16-bit one's complement checksum to protect against accidental data corruption.
Packet format
OSPFv3 runs directly over IPv6. All other addressing information is absent in OSPF packet
headers. OSPFv3 is network-protocol-independent. LSA types now contain addressing
information.
OSPFv3 implements the following packet changes:
• The hello packet and database description packet operations fields are expanded to 24
bits.
• The packet header does not include Authentication and AuType fields.
• The interface ID replaces the address information in the hello packet. The Interface ID
becomes the network LSA link state ID if the router becomes the designated router on
the link.
• R-bit and V6-bit in the options field process router LSAs during Shortest Path First (SPF)
calculation. R-bits and V6-bits determine participation in topology distribution.
• The packet header includes the Instance ID, which allows multiple OSPF protocol
instances on the same link.
R-bit
Unlike OSPF for IPv4, OSPFv3 for IPv6 supports the R-bit (Router bit). The R-bit indicates
whether the originating node is an active router.
If the R-bit is cleared, routes that transit the advertising node cannot be calculated.
As an example, if a multi-homed host wishes to participate in routing without forwarding non-
locally addressed packets, the R-bit is cleared.
Note that this means that an IPv6-enabled switch can continue to operate as an OSPFv3
neighbor even if you disable IPv6 forwarding on the switch. This behavior differs from IPv4
OSPF, in which the switch drops a neighbor if IP forwarding on the neighbor is disabled.
OSPFv3
Configuration — IPv6 Routing November 2010 49