Information Technology Reference
In-Depth Information
OSPFv3 Summary
OSPFv3 is used in large enterprise IPv6 networks. The network topology must be hierar-
chical. OSPF is used in the enterprise campus building access, distribution, and core lay-
ers. OSPF is also used in the enterprise data center, WAN/MAN, and branch offices.
The characteristics of OSPFv3 follow:
Link-state routing protocol for IPv6.
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Uses IPv6 Next Header 89.
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Metric is cost (based on interface bandwidth by default).
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Sends partial route updates only when changes occur.
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Routes are labeled as intra-area, interarea, external Type 1, or external Type 2.
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Uses IPv6 for authentication.
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Uses the Dijkstra algorithm to calculate the SPF tree.
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Default administrative distance is 110.
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Uses multicast address FF02::5 (ALLSPFRouters).
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Uses multicast address FF02::6 (ALLDRouters).
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Fast convergence, scalable, and reduces bandwidth.
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Recommended for large IPv6 networks.
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This section covers Border Gateway Protocol theory and design concepts. The current
version of BGP, Version 4, is defined in RFC 1771 (March 1995). BGP is an interdomain
routing protocol. What this means is that you use BGP to exchange routing information
between autonomous systems. (It is used for inter-autonomous system routing.) The pri-
mary function of BGP is to provide and exchange network-reachability information be-
tween domains or autonomous systems. BGP is a path-vector protocol. BGP is best suited
for s et t ing rout ing polic ie s bet ween autonomou s s ystem s. In the enter pr is e c ampu s archi -
tecture, BGP is used in the Internet connectivity module.
BGP is the de facto standard for routing between service providers on the Internet be-
cause of its rich features. You can also use it to exchange routes in large internal networks.
The Internet Assigned Numbers Authority (IANA) reserved TCP port 179 to identify the
BGP protocol. BGPv4 was created to provide CIDR, a feature that was not present in the
earlier versions of BGP. BGP is a path-vector routing protocol; it is neither a distance-vec-
tor nor link-state routing protocol.
Note:
RFC 1519 describes CIDR, which provides the capability to forward packets based
on IP prefixes only, with no concern for IP address class boundaries. CIDR was created as
