[c-nsp] OSPF routing question

[adamv0025 at netconsultings.com]

> Lee Starnes
> Sent: Tuesday, July 17, 2018 10:17 PM
> 
> Is there a
> way to allow the /22 block to propagate to the edge routers and still
maintain
> the hold down routes we need to announce that /22 via BGP to our various
> upstream carriers?
> 
One problem I'd see with this setup is potential black holing for the /22 in
question.
Imagine a case where one of your edge routers becomes severed from the rest
of the network for some reason, if that edge router has a static route being
advertised via BGP to upstream carriers then it will still advertise the /22
route even though it can not reach the rest of the network or the /22.
That's why I'd recommend letting the edge routers to learn the /22 via OSPF
and then use network command in BGP to capture the /22 (if it exists in
local routing table)and then advertise it to upstreams (and then removing
the static routes for /22).

Not sure if network command still reflects the changes in metric into MED
attribute, if it does then setting static MED in policy associated with the
network command should stop internal metric changes to be propagated outside
of the local AS. 
 
adam    

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