Siemens SIMATIC NET System Manual page 48

Basics of communication with Industrial Ethernet
1.3 Technologies of Industrial Ethernet
System Area Border Router (ASBR). On the ASBR, one interface is connected to another
AS, for example, an AS that uses the RIP routing protocol.
With OSPF, messages can be authenticated. Only trustworthy routers can take part in the
routing with OSPF.
OSPFv3
Version 3 of OSPF is based on Version 2 and is only used with IPv6. A large part of the
routing mechanisms was adopted. In comparison to OSPFv2 the following changes or
extensions apply for OSPFv3:
● The authentication available in version 2 has been removed. Instead OSPFv3 uses
IPsec, that is implemented in IPv6.
● The neighbor routers are identified via the router ID.
● The neighbor database (link state database - LSDB) is divided into different areas of
application: Link Scope LSDB, Area Scope LSDB and AS-Scope LSDB.
● Two new LSA types were defined for OSPFv3 (Link LSA and Intra-Area Prefix LSA).
● In contrast to OSPFv2, OSPFv3 can forward unknown LSA types. Previously, these were
deleted and not distributed further.
Dynamic routing with RIPv2
The Routing Information Protocol (RIPv2) is used to create routing tables automatically.
RIPv2 is used in autonomous systems (AS) with a maximum of 15 hops. It is based on the
Distance-Vector algorithm.
Since a router initially only knows its directly connected networks, it sends a request to its
direct neighbor routers. As the reply, it receives the routing tables of the neighbor routers.
Based on the received information the router sets up its own routing table.
Once the routing table is set up, the router sends its routing table to each direct neighbor
router via the UDP port 520 at intervals of 30 seconds.
The router compares new routing information with its existing routing table. If the new
information includes shorter routes, the existing routes are overwritten. The router only
keeps the shortest route to a destination.
If a router does not receive messages from a neighbor router for longer than 180 seconds, it
marks the router as being invalid. The router assigns the metric 16 for the neighbor router.
RIPng
RIPng (RIP next generation) is only used with IPv6 and is defined in RFC 2080. As with RIP
(IPv4), RIPng is based on the distance-vector algorithm of Bellman-Ford.
In contrast to RIPv2, RIPng is activated directly at the interface (VLAN interface / router port)
and not globally on the device. RIPng uses the UDP port 521 and RIP the UDP port 520.
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System Manual, 09/2019, C79000-G8976-C242-10
Industrial Ethernet