Network Router User Manual

■ BGP—Border Gateway Protocol, version 4, is an Exterior Gateway Protocol
(EGP) that guarantees loop-free exchange of routing information between
routing domains (also called autonomous systems). BGP, in conjunction with
JUNOS routing policy, provides a system of administrative checks and
balances that can be used to implement peering and transit agreements.
■ ICMP—Internet Control Message Protocol router discovery is a method that
hosts can use to discover the addresses of operational routers on a subnet.
■ IS-IS—Intermediate System-to-Intermediate System is a link-state interior
gateway protocol (IGP) for IP networks that uses the shortest-path-first
algorithm (SPF algorithm, also called the Dijkstra algorithm) to determine
routes.
■ OSPF—Open Shortest Path First, version 2, is an IGP developed for IP
networks by the Internet Engineering Task Force (IETF). OSPF is a link-state
protocol that makes routing decisions based on the SPF algorithm.
■ RIP—Routing Information Protocol, version 2, is an IGP for IP networks
based on the Bellman-Ford algorithm. RIP is a distance-vector protocol. RIP
dynamically routes packets between a subscriber and a service provider
without the subscriber having to configure BGP or to participate in the service
provider’s IGP discovery process.
■ Multicast routing protocols
■ DVMRP—Distance Vector Multicast Routing Protocol is a dense-mode
(flood-and-prune) multicast routing protocol.
■ IGMP—Internet Group Management Protocol, versions 1 and 2, is used to
manage membership in multicast groups.
■ MSDP—Multicast Source Discovery Protocol enables multiple PIM sparse
mode domains to be joined. A rendezvous point (RP) in a PIM sparse mode
domain has a peering relationship with an RP in another domain, thereby
discovering multicast sources from other domains.
■ PIM sparse mode and dense mode—Protocol-Independent Multicast is a
multicast routing protocol used to route traffic to multicast groups that might
span wide-area and interdomain internetworks. In PIM sparse mode, routers
explicitly join and leave multicast groups. PIM dense mode is a
flood-and-prune protocol.
■ SAP/SDP—Session Announcement Protocol and Session Description Protocol
handle conference session announcements.
■ MPLS application protocols
■ LDP—Label Distribution Protocol provides a mechanism for distributing
labels in nontraffic-engineered applications. LDP allows routers to establish
label-switched paths (LSPs) through a network by mapping network-layer
routing information directly to data-link layer switched paths. LSPs created
Routing Engine Software Components ■ 27
Chapter 3: JUNOS Internet Software Overview