HP VPN Firewall Appliances Appendix Protocol Reference

2
• NextHop—Next hop.
• Interface—Output interface.
Dynamic routing protocols
Static routes work well in small stable networks. They are easy to configure and require fewer system
resources. However, in networks where topology changes occur frequently, a typical practice is to
configure a dynamic routing protocol. Compared with static routing, a dynamic routing protocol is
complicated to configure, requires more resources, and consumes more network resources.
Dynamic routing protocols dynamically collect and report reachability information to adapt to topology
changes. They are suitable for large networks.
Dynamic routing protocols can be classified by different criteria, as shown in Table 2:
Table 2 Categories of
dynamic routing protocols
Criterion Cate
g
ories
Optional scope
• IGPs—Work within an AS. Examples include RIP, OSPF, and IS-IS.
• EGPs—Work between ASs. The most popular one is BGP.
Routing algorithm
• Distance-vector protocols—RIP and BGP. BGP is also considered a path-vector
protocol.
• Link-state protocols—OSPF and IS-IS.
Destination address
type
• Unicast routing protocols—RIP, OSPF, IS-IS, and BGP.
• Multicast routing protocols—PIM-SM and PIM-DM.
IP version
• IPv4 routing protocols—RIP, OSPF, IS-IS, and BGP.
• IPv6 routing protocols—RIPng, OSPFv3, IPv6 IS-IS, and IPv6 BGP.
An AS refers to a group of routers that use the same routing policy and work under the same
administration.
Route preference
Routing protocols (including static and direct routing) each by default have a preference. If they find
multiple routes to the same destination, the router selects the route with the highest preference as the
optimal route.
The preference of a direct route is always 0 and cannot be changed. You can configure a preference for
each static route and each dynamic routing protocol as required. The following table lists the route types
and default preferences. The smaller the value, the higher the preference.
Table 3 Route types and default route preferences
Route t
yp
e Preference
Direct route 0
OSPF 10
IS-IS 15
Static route 60