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Router Node 23
Host extensions for IP multicasting as described in RFC 1112 are
also provided. The Router Manager acts as a host and uses the
Internet Group Management Protocol
(IGMP), version 2, to add and
delete its membership in multicast groups. Accordingly, the Route
Manager "joins" the appropriate routing protocol host groups for
OSPF and RIP.
• IS-IS
Intermediate System to Intermediate System (an OSI gateway
protocol) is a protocol similar to OSPF: it also uses a Link State,
Shortest Path First algorithm. However, IS-IS is an OSI protocol used
for routing
Connectionless Network Protocol
(CLNP) packets within a
routing domain. CLNP is the OSI protocol most comparable to IP.
• Exterior Routing Protocols
Exterior Routing Protocols are used to exchange routing information
between routers in different autonomous systems. Here is the list of
exterior routing protocols supported by the GRF:
•EGP
The
Exterior Gateway Protocol (EGP)
is the protocol used for
exchange of routing information between
exterior
gateways (not
belonging to the same autonomous system).
EGP gateways may only forward reachability information for networks
within their autonomous system. This routing information must be
collected by the EGP gateway, usually via an GP).
•BGP
Border Gateway Protocol
(BGP) is the leading exterior routing protocol
of the Internet and is replacing EGP as the exterior protocol of choice.
It is based on the OSI
InterDomain Routing Protocol
(IDRP). BGP
supports policy-based routing, which uses nontechnical reasons (for
example, organizational, political, or security considerations) to make
routing decisions. Thus, BGP enhances an autonomous system’s
ability to choose between routes and to implement routing policies
without relying on a central routing authority.
2.2.3 Filtering
IP filtering supports specific permit or deny decisions for each instance of a
filter (per logical interface). The criteria within each filter may include any
combination of the following:
• Protocol (ICMP, TCP, UDP)