Siemens SCALANCE XM-400 Configuration Manual page 62

Technical basics
4.8 Routing function
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Router LSA (LSA Type 1)
The LSA Type 1 is only sent within an area. For each active connection of the router
that belongs to the area in consideration, an LSA Type 1 is generated. The LSA Type 1
contains information about the status and the costs of the connection, for example IP
address, network mask, network type
Network LSA (LSA Type 2)
The LSA Type 2 is sent only within an area. For each network that belongs to the relevant
area, the router generates an LSA Type 2. If several routers are interconnected in a
network, the LSA Type 2 is sent by the designated router (DR). The LSA Type 2 includes
the network address, the network mask and a list of routers that are connected to the
network
Summary LSA (LSA Type 3 / LSA Type 4)
The Summary LSA is generated by the area border router and sent into the area. The
Summary LSA contains information about routes outside the area but inside the AS.
Where possible, the routes are grouped together.
● Summary LSA (LSA Type 3)
The LSA Type 3 describes the routes to the networks and advertises the standard
route to the areas.
● AS Summary LSA (LSA Type 4)
The LSA Type 4 describes the routes to the ASBR.
External LSA (LSA Type 5 / LSA Type 7)
The External LSA is generated by the ASBR. The LSA type depends on the area.
● AS External LSA (LSA Type 5)
The LSA Type 5 is sent by the AS border router into the areas of the autonomous
system except the Stub and NSSA areas. The LSA contains information about routes
to a network in another AS. The routes are either created manually or learned
externally. The ASBR uses LSA Type 5 to distribute standard routes to the backbone
area.
● NSSA External LSA (LSA Type 7)
The LSA Type 7 is generated by the AS border router of an NSSA. The router is also
known as the NSSA ASBR. The LSA Type 7 is sent only within the NSSA. If the P
bit in LSA Type 7 = 1, these LSAs are converted to LSA Type 5 by the ABR and sent
to the backbone area.
SCALANCE XM-400/XR-500 Web Based Management (WBM)
Configuration Manual, 05/2017, C79000-G8976-C248-12