HP-UX Routing Services Administrator's Guide HP-UX 11i v2, HP-UX 11i v3 (B2355-91153, November 2011)
gated supports the following interior gateway protocols, as defined in IETF RFCs:
• Routing Information Protocol (RIP) is a common routing protocol used within an autonomous
system. A de facto industry standard, it is also used by routed, a service distributed by
Berkeley. RIP is not intended for use in wide area network (WAN) applications. There are
currently two versions of RIP implementations: Version 1, as defined in RFC 1058, and Version
2, as defined in RFC 1388. gated supports all Version 1 features and most of the features
of Version 2. The following Version 2 features are not supported: RIP management information
base (MIB) route tag, and route aggregation. gated 3.5.9 supports authentication.
• Open Shortest Path First (OSPF), similar to RIP, is a routing protocol that allows routing
information to be distributed between routers in an autonomous system. Each router on the
network transmits a packet that describes its local links to all other routers. The distributed
database is then built from the collected descriptions. If a link fails, updated information floods
the network, allowing all routers to recalculate their routing tables at the same time. OSPF is
more suitable than RIP for routing in complex networks with many routers. gated 3.0 supports
most of the features of OSPF Version 2, as described in RFC 1247, except the IP type of
service (TOS) routing feature. Equal cost multipath routes are limited to one hop per destination,
because the HP-UX kernel supports only one gateway per route.
• HELLO is designed to work with routers called Fuzzballs. Most installations use RIP or OSPF
instead of HELLO. The HELLO protocol is no longer supported on HP-UX. You can use RIP or
OSPF instead, because they are internal routing protocols.
NOTE: Do not mix RIP and OSPF protocols within a single network, because the routing information
may conflict.
Table 1 compares the advantages and disadvantages of the RIP and OSPF protocols.
Table 1 Comparison of RIP and OSPF Protocols
OSPFRIP
Disadvantage: OSPF is complicated to configure and
requires network design and planning.
Advantage: RIP is easy to configure.
Disadvantage: OSPF does not have a passive mode.Advantage: An end system (a system with only one network
interface) can run RIP in passive mode to listen for routing
information.
Advantage: OSPF is quick to adjust for link failures.Disadvantage: RIP may be slow to adjust for link failures.
Advantage: OSPF generates less protocol traffic than RIP,
because (i) Each router transmits information only about
Disadvantage: RIP generates more protocol traffic than
OSPF, because it propagates routing information by
its links instead of the whole routing table, and (ii) OSPFperiodically transmitting the entire routing table to neighbor
routers. allows you to divide an autonomous system into areas,
each with a designated router that exchanges inter-area
routing information with other routers. Intra-area routing
information is isolated to a single area.
Advantage: OSPF works well in large networks.Disadvantage: RIP is not appropriate for large networks,
because RIP packet size increases as the number of
networks increases.
gated supports the following exterior gateway protocols:
• The External Gateway Protocol (EGP) permits a node on the NSFNET backbone to exchange
information with other backbone nodes about reaching a destination. You can use EGP to
communicate routing information between autonomous systems. The EGP protocol will be
obsoleted in a future release of HP-UX. Use BGP instead of the EGP protocol. BGP offers more
flexibility and requires less bandwidth than EGP.
• The Border Gateway Protocol (BGP) is intended as a replacement for EGP. BGP uses path
attributes to select routes. One of the attributes that BGP can pass is the sequence of autonomous
12 Overview