From: Howard C. Berkowitz (hcb@gettcomm.com)
Date: Mon Dec 02 2002 - 10:33:45 GMT-3
All correct. Let me complete the list and also add some new types
that, right now, are used mainly for MPLS traffic engineering.
At 11:06 AM +0000 12/2/02, Adam Crisp wrote:
>Hi,
>
>This is probably some help to you!
>
>Type 1 = Router Link Advertisements , generated by every router.
>Type 2 = Multi-access segment Network Link Advertisements , generated by DR
>Type 3 = Summary Link Advertisements. Summary, generated by the ABR for
>EVERY type 1,2. Type 3 can be generated to describe a summary for a bigger
>lump of addresses. Works in both directions, so that a Type 3 from Area 1,
>can traveres the backbone and go into say Area 2. Depends upon your
>configuration.
>Type 4 = Summary Link Advertisements. Generated by ASBR.
>Type 5 = Autonomous System (AS) External Link Advertisements. Generated by
>ASBR.
Type 6 = used by multicast OSPF (MOSPF), which, in practice, is an
obsolete and dead protocol. Cisco never implemented in -- Proteon
is the only vendor that really ever supported it.
>Type 7 = Not-So-Stubby Areas (NSSA). Generated by external route sources
>within a NSSA, or by the ABR ro a NSSA area.
Type 8 = Database Overflow. Again, obsolete and, AFAIK, never implemented
in a production router. Its function let OSPF do some things that iBGP
does better.
Type 9 = Opaque LSA with scope of single subnet.
Type 10 = Opaque LSA with scope of single area
Type 11 = Opaque LSA with scope of entire OSPF domain.
Opaque LSAs contain no topology information directly relevant to
OSPF, but use OSPF flooding to distribute other information to the
OSPF-speaking routers. They have been used for such things as
distributing load information, ATM to IP mappings, a thought of using
OSPF to transport IPX, etc.
I'd say it's possible that you might see opaque on the written, but I
suspect it would be unlikely to see them in the current lab with its
platforms and non-service-provider-train IOS.
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