A rough comparison of OSPFv3 and OSPFv2

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OSPFv2 (IPV4) Brief Review (RFC2328):

--support for large-scale routing

--Fast convergence of routing changes

--No routing loops

--support for equivalent load balancing (LSA link State routing protocol, only support equivalence, non-equivalence is EIGRP and BGP can support)

--Support regional grading management

--Support Routing hierarchy management

--Support validation (clear text validation and MD5 validation)

--Support for group advertisement sending protocol messages (224.0.0.5 and 224.0.0.6)

The OSPFV2 protocol number is 89.

Router-id is a 32-bit unsigned integer, which is a unique indicator of a router, so it is generally represented by a ring. The only one within the entire as.

The router (IAR) in the zone------all the interfaces of the router belong to the same OSPF area.

The zone boundary router (ABR)-----is responsible for transmitting routing information between different regions. The router belongs to more than two zones at the same time (one of the areas must be area0)

The autonomous system boundary router (ASBR)-----is responsible for introducing routing information from other autonomous systems, which introduces other routing protocols (redistribution).

PS. The various types of routers can be switched to each other (except for both IAR and ABR)

All types of routers are represented by a graph:

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The OSPFV2 abstracts all network topologies into three scenarios:

--stub Network, the network is connected to only its own routes.

--point-to-point network, which is connected to another router through a point-to network.

--broadcast (broadcast) or NBMA network: The router is connected to multiple routers through a broadcast network or NBMA network.

Interface type: (OSPF interface has five types)

-To-point (peer) interface

--point to Multipoint (P2MP) interface

--point to multipoint non-broadcast (P2MP Non-broadcast) interface

--Broadcast (broadcast) interface

-->nmba (non-broadcast multi-access) interface

The ~~~~~~virtual link interface is a special type of peer-to interface. (Create a virtual tunnel)

Flooding and link state database for OSPF

In an area of OSPF, the LSA is flushed to all routers, and eventually all routers in the zone are consolidated in the database.

Exchange LSA through everyone. (Flood of Type-1,type-2)

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OSPF There are five types of data messages:

-->hello messages, find and maintain neighbourhood relations, elect DR,BDR

-->DBD messages, describing the situation of local LSDB

-->LSR message, requesting the LSA to the peer without its own

-->LSU messages, updating LSA to each other

-->lsack message, after receiving LSU, to confirm

All messages use the same message header

In addition to the vlink, spread the distance on the other links as a hop.

OSPFv3 Protocol Introduction

---- OSPF routing Protocol (RFC2740) running on IPv6

---based on OSPFv2 fundamentals and enhancements, is an independent routing protocol. The protocol number is still 89,router-id is still a 32-bit unsigned integer. [Router-id here is not a format for IP address in IPv6, but a 32-bit unsigned integer]

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Although many concepts of OSPFv3 and V2 are the same, they are not compatible with each other.

OSPFv3 and the OSPFv2 the different points :

1, Based on connection (Link), rather than the network (subnet) Run

The topology description of the OSPFV3 relies on the link-local address of the IPv6 and from any address of IPv6.

In fact, even if there is no OSPF unicast address on the link, it can also form a neighbor relationship. Because the source is the link-local address, the purpose is the multicast address, so that OSPF interaction can be completed.

Here are two examples:

OSPFv2 is a link-based operation. For example, below, in the same MA network, it must be everyone to subnet segment has been, mask consistent, in order to establish a neighbor relationship.

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While the OSPFv3 is as follows, each router is connected to the MA network, and the subnets are different.

RTA=5F00.1111::1/32 RTB=5F00.2222::1/32 RTC=5F00.3333::1/32

Even so, they can build up OSPF neighbor relationships, because the link-local is used as the source address.

Because the topology database to describe the thing completely and address does not matter, the database needs to describe is rta/b/c in the same subnet, cost is enough. (There is not much relationship between the specific network segment and the database)

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2,ipv6 address semantics and protocol design separation

The topology description of the OSPFV3 relies on the link-local address of the IPv6 and from any address of IPv6.

In fact, even if there is no OSPF unicast address on the link, it can also form a neighbor relationship. Because the source is the link-local address, the purpose is the multicast address, so that OSPF interaction can be completed.

Where does it manifest the separation of semantics and protocol design?

1, the link-local address of IPV6 is used to pass the network topology information, but the IPV6 address is not included in the topology information.

2,router-lsa and Network-lsa only reflect network topology information;

3, use dedicated LSA to pass IPV6 prefix information (intra-area prefix LSA)

4,router-id,area ID and LSA link state ID remain in IPV4 format (32bit) instead of IPV6 address

5, the neighbor is marked by the neighbor router ID.

3, clear LSA Flood range and increase link-local flooding range

In IPv4, Router-lsa and Network-lsa are flooded within the region. Type-3 summary LSA is flooding between regions, type-4 is interregional, and type-5 is flooding the whole network .... But this range is all about flooding within or between regions.

For OSPFv3, however, a link range has been added to flood.

1, the new LSA is added to the Type-8 and is only flooded within the local link range. Flood range: Link local (link-local scope)

2, zone scope (area scope): Router-lsa, Network LSA, Inter-area-prefix-lsa

Inter-area-router-lsa, As-nssa-lsa (exists only in NSSA area)

Intra-area-prefix-lsa (New)

3, autonomous system range (as scope): As-external-lsa

Flood Range
Link Local flooding	Link-lsa (link-local Scope) Type-8
Flooding in the area	Router-lsa (Type-1)
	Network-lsa (Type-2)
	Intra-area-prefix-lsa (IPv6 prefix in the hosting area) Type-9
Within the Nssa area	As-nssa-lsa (Type-7)
Flooding between regions	Inter-area-prefix-lsa
	Inter-area-router-lsa
Flooding in as	As-external-lsa (type-5)

4, multi-instancing of connection (link)

Multi-instance applications.

Scenario 1: Here a/b/c/d are all in the same subnet, and the expected result is:

a--d form a neighbor/adjacency relationship.

B--c form a neighbor/adjacency relationship.

A-X-C has no relationship. B-x-d has no relation whatsoever.

Not in IPv4, but in IPv6, add a field called Instance-id in the Hello package. Also, as a must match field, the neighbor cannot be established.

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5, using the link-local (link-local) address

In addition to virtual link (virtual link is actually a tunneling technology, has exceeded the link range), the other links sent the source address is link-local address, the destination address is link-local address or a multicast address. [In fact, there is no negotiation at all with a unicast address]

6, verification and validation and change

Autype and authentication are no longer included in the OSPFV3 message, and they rely on IPV6 's extended Authentication header for authentication.

Efficacy and checksum changes:

OSPFV3 uses the IPV6 standard check sum. IPV6 and coverage of the IPV4, will cover the IPv6 Baotou.

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7, Message format changes

Here are the changes in the Baotou of OSPFv2 and V3:

In V2, there are many fields of authentication, and there is no after V3.

But V3 adds a instance ID so that you can do long instances of neighbor relationships.

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Description of the OSPFv3 header field:

--version: Version, for OSPFv2, the value =2,ospfv3=3.

--type:1-hello,2-dd,3-lsr,4-lsu,5-lsack

--packet length:ospfv3 Message length

--router ID: Router ID, network-wide unique.

--area ID: The zone ID, in addition to the virtual connection. All others need to be connected to the backbone area.

--checksum: Efficacy and

--instance ID: link instance ID. You must match the neighbors, or the 2way will not be built. V3 add field.

8,lsa changes in type and format

In addition to the sixth is never enabled, 8 and 9 and new additions.

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A rough comparison of OSPFv3 and OSPFv2