H3C Technologies H3C S7500E Series Switches - Manual (Page 21)

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z Exterior gateway protocols (EGPs): Work between autonomous systems. The most popular one is
BGP.
An autonomous system refers to a group of routers that share the same routing policy and work under
the same administration.
Routing algorithm
z Distance-vector protocols: RIP and BGP. BGP is also considered a path-vector protocol.
z Link-state protocols: OSPF and IS-IS.
The main differences between the above two types of routing algorithms lie in the way routes are
discovered and calculated.
Type of the destination address
z Unicast routing protocols: RIP, OSPF, BGP, and IS-IS.
z Multicast routing protocols: PIM-SM and PIM-DM.
This chapter focuses on unicast routing protocols. For information on multicast routing protocols, see
the IP Multicast Configuration Guide.
Version of IP protocol
IPv4 routing protocols: RIP, OSPFv2, BGP4, and IS-IS.
IPv6 routing protocols: RIPng, OSPFv3, BGP4+, and IPv6 IS-IS.
Routing Protocols and Routing Priority
Different routing protocols may find different routes to the same destination. However, not all of those
routes are optimal. In fact, at a particular moment, only one protocol can uniquely determine the
current optimal route to the destination. For the purpose of route selection, each routing protocol
(including static routes) is assigned a priority. The route found by the routing protocol with the highest
priority is preferred.
The following table lists some routing protocols and the default priorities for routes found by them:
Routing approach Priority
DIRECT 0
OSPF 10
IS-IS 15
STATIC 60
RIP 100
OSPF ASE 150
OSPF NSSA 150