3com S7906E Manuel De Montage

 

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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. 

 

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Distance-vector protocols: RIP and BGP. BGP is also considered a path-vector protocol. 

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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. 

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Unicast routing protocols: RIP, OSPF, BGP, and IS-IS. 

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Multicast routing protocols: PIM-SM and PIM-DM. 

This chapter focuses on unicast routing protocols. For information on multicast routing protocols, refer 

to the IP Multicast Volume. 

IPv4 routing protocols: RIP, OSPFv2, BGP4, and IS-IS. 

IPv6 routing protocols: RIPng, OSPFv3, BGP4+, and IPv6 IS-IS. 

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: 

DIRECT 

0 

OSPF 10 

IS-IS 15 

STATIC 60 

RIP 100 

OSPF ASE 

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