Information Technology Reference
In-Depth Information
Ta b l e 9 - 9
IPv6 Mechanisms
Description
IPv6 Mechanism
Cisco routing protocol for IPv6.
EIGRP for IPv6
Link-state routing protocol for IPv6.
OSPFv3
New routing protocols have been developed to support IPv6, such as RIPng, Intermediate
System-to-Intermediate System (IS-IS), Enhanced Interior Gateway Routing Protocol
(EIGRP) for IPv6, and Open Shortest Path First Version 3 (OSPFv3) Protocol. Border
Gateway Protocol (BGP) also includes changes that support IPv6. These routing protocols
are only briefly mentioned here because they are covered in detail in Chapter 10, “Routing
Protocol Characteristics, RIP, and EIGRP,” and Chapter 11, “OSPF, BGP, Route Manipula-
tion, and IP Multicast.”
RIPng
RFC 2080 describes changes to RIP to support IPv6 networks, called RIP next generation
(RIPng). RIP mechanisms remain the same. RIPng still has a 15-hop limit, counting to in-
finity, and split horizon with poison reverse. Instead of User Datagram Protocol (UDP)
port 520 for RIPv2, RIPng uses UDP port 521. RIPng supports IPv6 addresses and pre-
fixes. Cisco IOS software currently supports RIPng. RIPng uses multicast group FF02::9
for RIP update s to all RIP router s.
EIGRP for IPv6
Cisco has developed EIGRP support for IPv6 networks to route IPv6 prefixes. EIGRP for
IPv6 is configured and managed separately from EIGRP for IPv4; no network statements
are used. EIGRP for IPv6 retains all the characteristics (network discovery, DUAL, mod-
ules) and functions of EIGRP for IPv4. EIGRP uses multicast group FF02::A for EIGRP
updates.
OSPFv3
RFC 2740 describes OSPFv3 to support IPv6 networks. OSPF algorithms and mecha-
nisms (flooding, designated router [DR] election, areas, shortest path first [SPF] calcula-
tions) remain the same. Changes are made for OSPF to support IPv6 addresses, address
hierarchy, and IPv6 for transport. Cisco IOS software currently supports OSPFv3.
OSPFv3 uses multicast group FF02::5 for all OSPF routers and FF02::6 for all DRs.
IS-IS for IPv6
Specifications for routing IPv6 with integrated IS-IS are currently an Internet draft of the
IETF. The draft specifies new type, length, and value (TLV) objects, reachability TLVs, and
for IP v6 as c ur rently de s c r ibed in the draft standard.
