Extensions to OSPFv2 for Advertising Optional Route/Link Attributes draft-mirtorabi-ospf-tag-00.txt Sina Mirtorabi

Draft purpose The goal is to advertise optional link / route attribute One of the applications is to advertise tags in internal OSPF routes Other applications could define other attributes in the future

Route-attribute (RA) LSA Current LSAs are not extensible A new LSA, called route attribute LSA is defined to advertise attribute for different LSA types RA LSA is an opaque LSA type 9, 10 or 11 depending on application and flooding scope. RA LSA payload is TLV based Opaque-id is divided into one byte “Attr LS type” referencing an LSA and two bytes unique ID

Route-attribute (RA) LSA LS ageOptions9,10,11 Opaque typeAttr LS typeUnique ID Advertising Router LS Sequence number LS checksumLength TLV

RA LSA TLV types Four TLV are currently defined 1.Link attribute TLV (type 1) 2.Inter-area route TLV (type 2) 3.External route TLV (type 3) 4.NSSA external TLV (type 4)

Link Attribute TLV (type 1) TLV type (1)TLV Length Link-type0 Link ID Link Data sub-TLV

Inter-area / external route TLV TLV Type (2/3/4)TLV Length Link State ID R| R| P-Length0 sub-TLV

Inter-area / external route TLV TLV Type (2/3/4)TLV Length Link State ID R| R| P-Length0 sub-TLV

Sub-TLVS Three sub-TLVs are currently defined 1.Standard Tag (type 1) 2.Extended Tag (type 2) 3.Multi-topology ID (type 3)

Standard tag sub-TLV (type 1) sub-TLV type (1)sub-TLV Length tag ::: tag

Extended tag sub-TLV (type 2) sub-TLV type (2)sub-TLV Length Extended Tag :::: Extended Tag

Multi-topology ID TLV (type 3) sub-TLV type (3)sub-TLV Length MT-ID0 sub-TLV

Generation of RA LSA A router configured to advertise link or route attribute, generates a RA LSA corresponding to one of its self originated LSA. RA LSA is regenerated only when there is a change in attribute value Across area boundary, an ABR will generate  Area scoped RA LSA to associate attribute to type 3 / type 4 LSA  AS scoped LSA to associate attribute to translated NSSA routes  Local policy could overwrite the default behavior

Backward compatibility There is no backward compatibility issues as new LSA is ignored by non-capable router In order to advertise attribute across areas, ABRs should be capable unless the flooding scope is AS scope.

We would like draft-mirtorabi-ospf-tag-00.txt to be accepted as a OSPF WG document