There is some problem with upload diagram, even small, here is link:
http://pokazywarka.pl/mg6gtf/
[url=http://pokazywarka.pl/mg6gtf/]diagram[/url]
W dniu 2013-03-24 11:36, Piotr pisze:
Hi
I attached diagram. I have to connect together two different companies.
They have ethernet leased lines, so i can use bgp on private AS numbers.
Each have own OSPF. There is max 1k routes in igp. In this moment i use
only ebgp, i removed ibgp. I made redistrubutions ospf-(e)bgp and
(e)bgp-ospf on A1 A2 B1 B2, i have also tags against mutual
redistributions. Ebgp has 200 ad on cisco, For now all works, but first
time without ibgp. I'm affraid about some problems like loops..
thanks for any advice or notice
regards,
Piotr
W dniu 2013-03-23 22:29, Patrick Okui pisze:
Hi Piotr,
On 23-Mar-2013 16:13:18 (+0200), Piotr wrote:
I have to connect two networks via bgp, both have own ospf area0, there
are 2 points od redistribution between BGP and OSPF. We use med to have
symmetry, because Junipers must work in flow based (ipsec).
Probably a small ascii diagram would help in this case. If you're using
MED then these two networks are two separate ASes correct? Juniper in
one, Cisco in another?
When we set on cisco default AD, on juniper we change bgp ad to 20 (
The default AD of eBGP in Cisco is 20, but of iBGP is 200. However,
Cisco by default will wait to see a route in the IGP before installing
it into BGP. I usually set both to 200 (and turn off synchronisation)
thusly:
router bgp NN
distance bgp 200 200 200
no synchronisation
You may also want to set bgp deterministic-med on the cisco side to
match how most other vendors treat MED.
like in Cisco) juniper prefer routes from ibgp and there is a problem
with redistribution between ospf and ebgp because there is no prefix
from ospf in rib.
one of BGP's first rules is reachability to the next hop. If BGP can't
reach the next hop it will drop the prefix advertisment. Your IGP has to
guarantee this.
I think that when i remove internal bgp session there should be ok, in
rib there will be prefixes only from ospf so there will be no problem
wirh redistribution? There are some disadvantages when there is no
ibgp ?
I think my first question is ... why are you redistributing in the first
place? iBGP will handle more prefixes than any IGP - so usually you just
want to carry your infrastructure/interface/link prefixes in the IGP and
everything else in BGP. If you go down this route, then a full iBGP
mesh[*] between BGP speakers is required to avoid loops.
Again, it's not easy to guess what you're trying to achieve without a
diagram.
Will OBrien's comments above give hints on getting redistribution
working but then again, we're all shooting in the dark.
--
patrick
[*] or a route reflector or ...
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