4.0.0.0/8?

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1

Did Level3 withdraw 4.0.0.0/8 today and start announcing it as two /9s?

-Hank

2

I don't know if it was today, but I see two /9s.

3

Newbie question:

If I do:
route-views>sho ip bgp 4.0.0.0
BGP routing table entry for 4.0.0.0/9, version 821994

why do I see the /9 and not the /8 by default? If I do a specific lookup for 4.0.0.0/8 it is there as well.

Thanks,
Hank

4

routeviews says the /9s have been announced for a while

the route object for 4.0.0.0/9 was last updated 20060203

5

Newbie question:

If I do:
route-views>sho ip bgp 4.0.0.0
BGP routing table entry for 4.0.0.0/9, version 821994

why do I see the /9 and not the /8 by default? If I do a specific
lookup for 4.0.0.0/8 it is there as well.

more-specific wins unless you specifically ask for all routes.

6

Once upon a time, Hank Nussbacher <hank@efes.iucc.ac.il> said:

Newbie question:

If I do:
route-views>sho ip bgp 4.0.0.0
BGP routing table entry for 4.0.0.0/9, version 821994

why do I see the /9 and not the /8 by default? If I do a specific lookup
for 4.0.0.0/8 it is there as well.

I'd guess because that's the way routing lookups work; the more-specific
match always "wins".

7

Level3 has been announcing 2x /9's as well as the /8 for some time now,
ever since Telefonica's unfortunate incident where they allowed a
customer to hijack 12.0.0.0/8 because they don't prefix-list filter
customers properly IIRC.

8

<cough>I think they still don't</cough>
-chris