Some leaks in China/Hongkong

Havard Eidnes he at
Sun Oct 26 17:28:29 CET 2008


I think you are misunderstanding or overlooking a passage in
Bernhard's message:

> Additionally, these problems are very much amplified by the
> current policy of most RENs to prefer (through localpref) their
> fellow RENs and tag their prefixes accordingly. As soon as
> someone does this on an unfiltered link, as Abilene does for
> Kreonet, it creates havoc.

As is the case for NORDUnet as well.  We see the route via a
shorter AS path since we peer with, but due to local-pref
for routes we receive from our R&E network providers, we
currently prefer the long path around:

he at dk-ore-re1> show route 2001:470:0:69::2                                  

inet6.0: 1431 destinations, 4445 routes (1429 active, 0 holddown, 634 hidden)
+ = Active Route, - = Last Active, * = Both

2001:470::/32      *[BGP/170] 1d 12:01:46, localpref 110
                      AS path: 20965 11537 17579 4635 6939 I
                    > to 2001:798:15:10aa::1 via so-0/1/0.0
                    [BGP/170] 1w2d 13:55:47, MED 1, localpref 100
                      AS path: 6939 I
                    > to 2001:7f8:1::a500:6939:1 via ge-0/2/0.501
                    [BGP/170] 4w2d 15:29:58, MED 2583, localpref 100
                      AS path: 3549 6939 ?
                    > to 2001:450:2002:c::1 via ge-2/2/0.0

he at dk-ore-re1> 

It also doesn't help that the BGP community marking we receive
from GÉANT and Internet2 gives precious little clue to discern
the route from "proper" R&E routes: we get 11537:2501 which says
"transit to international network" (not a useful distinction in
our view, we might want to use GÉANT and Internet2 to go to the
Korean R&E network) and 20965:11537 which says "we got this route
from Internet2" (an even less useful distinction).

OK, so one might argue that using local-pref is a stupid idea
anyway, but unfortunately it's a tool we need to use in order to
in some important cases prefer the appropriate path.

So, "sigh", I get to tweak our inbound routing policy for import
of GÉANT routes into NORDUnet once again (now done).


- Håvard

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