Routing

hi for all

i just want to know in ospf network how updates sent between all neighbors routers and its routing table populated with routes although the default export policy is to reject all routes ??

Based on the description something is probably incorrect in the configuration.  If the intentions is to apply a reject all policy then no routes should be advertised.

Do you want to share the policy, where it is applied and any ospf statistics you find relevant to seeing your issue.

I talking about default export policy ... If it exist so no routes will advertise between neighbors

Hi there,

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@jack_george wrote:

I talking about default export policy ... If it exist so no routes will advertise between neighbors

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OSPF does not "advertise routes", it generates and floods the LSA. On receiving end, these LSAs are inserted into local LSDB (in addition to self-generated LSAs) and refllooded onwards subject to OSPF flooding scope(s). It is not possible to stop propagating LSAs with export policy, see below.

The OSPF routes are "created" or "built" from LSDB using a litany of checks and algorithms, i.e. SPF is used inside each area and "distance vector" between areas.

Only when all checks pass and algorithms performed, then OSPF routes are inserted into local route table(s).

Export policy works inthe opposite direction - from route table into OSPF LSDB. Hence, You can only use export policy to stop inserting something (apart from direct/inteface routes, see below)  from local route table(s) into local OSPF LSDB. It is not possible to stop generating own LSAs for OSPF-enabled-interface routes with export policy since OSPF router LSAs are always generated accroding to RFC 2328.

HTH

Thanks
Alex

Are the same situation for RIP ,as RIP working by advertise routing table then increment metric also RIP not depends on LSA as OSPF so default export policy will prevent updates or what?

Thanks for support

Hello,

True, RIP does send "routes" and RIP export policy would prevent advertising all/specific routes to RIP neighbors.

However, to make Your life easier   , JUNOS has a default RIP export policy to "deny all" - even the direct/connected routes for RIP-enabled interfaces.

HTH

Thanks

Alex

OSPF export policy only applies for those non-OSPF routes in the routing-table on the box you wish to advertise into OSPF.  OSPF routes should exist on all neighbors via the LSAs that are shared within your OSPF area.  Each router in an OSPF area builds its own routes via the link-state database.

Ron

Do you means that inside OSPF area itself the export policy can not applied between OSPF neighbors ,it just work as redistribution between routing protocols.

thanks for support