IBM 9077 manual Filtering, Exterior Routing Protocols

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)

Router Node 23