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Re: iBGP based network. [9:2300] posted 12/10/2002
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Hi Guy,

my  email admin has put some stuff which keeps giving that ACI bit! no idea
why he has done so... sorry for that bit...

rest...inline...

----- Original Message -----
From: Guy Davies 
To: 'alok' ; 
Sent: Tuesday, December 10, 2002 5:29 PM
Subject: RE: iBGP based network. [9:2300]


>
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> Alok,
>
> First of all, what is +ACI- ?  A simple quote mark would appear to have
done
> ;-)
>
> Anyway, in answer to your question, you have several issues.
>
> If you plan to use the directly connected interfaces, you have a big
problem
> when any of those interfaces goes down.  Destinations attached to each of
> the routers linked by the failed circuit are unreachable to sources
attached
> to the router at the other end.  You have no means of doing multihop
because
> your peerings are setup between the physical interfaces.  You can't use
> loopbacks and set next-hop self because the loopbacks are not reachable
from
> other routers in your network.  You could try injecting loopbacks into
iBGP
> also, but then you rely on recursive lookups using BGP to resolve BGP
> next-hops (IIRC, some vendors don't allow this).

okie no multihop, i agreee........that doesnt matter to me right..no IGP
either...

>
> In the network you describe, your main problem is that A would be totally
> unknown to B (or x, depending upon which are the BGP routers).  Since A is
> directly connected to z and z redistributes directly connected routes into
> BGP, z will announce them with iBGP to y.  Unless y is a route reflector,
it
> will not announce any routes learned from z to x.  The only way to even
> start thinking about this is if you have a completely physically fully
> meshed network (yugh!) or a network in which there are route reflectors
> which are physically connected to every client in their cluster and
> physically connected to every other route reflector in the network.  Oh,
and
> they have to set next-hop self towards all their neighbours (clients and
> non-clients) where self is the address of the physical interface with
which
> they are attached to that specific neighbour!

...hmm so full mesh is a nice problem isnt it :o).......i wont next-hop
self, ill next-hop adjacent neighbour..but i still need a full mesh

>
> Why would you want to do this, what benefit does it bring?

just.. :o) ....wondering wht "iBGP not bouncing to another iBGP" ever gives
me actually....was it made with the intention of allowing "smaller routing
tables"......or it has a reason...u still have a "source" field in BGP to
recognise the source of the update dont u? so that "RIP equivalent" of
"split horizon" cud be knocked off with that....

>
> I'm not even going to bother with the question regarding duplicate
addresses
> in the network!  Suffice to say that you've got a single subnet appearing
on
> two interfaces on router y.  Which one do you choose to send the BGP
packet?
> What have you been smoking? ;-)

there was more than that i missed... i had the same IP appearing on one side
of the x router  and the same was on its other interface....

that was the bad bit.......sorry abt that.

i realised that immediately after i sent the mail and the "pot" wore
off....that ..its A-x-w-y-z-B ;o)

now can i have the same addresses on the interfaces between x-w and y-z
...yup not with all those issues u mentioned.....
:o)

actually here its linux-1 , linux 2, linux 3 , linux 4 linux 5 linux 6
...that i use... and i just relaised i dropped one linux when i sent that
mail....

anything else that fails?

>
> Regards,
>
> Guy
>
> > -----Original Message-----
> > From: alok [mailto:alok.dube@xxxxxxxxx]
> > Sent: Tuesday, December 10, 2002 8:09 AM
> > To: juniper@xxxxxxxxxxxxxx
> > Subject: iBGP based network. [9:2300]
> >
> >
> > Hi,
> >
> > this is not a +ACI-juniper specific+ACI- question, but
> > decided to bounce
> > this off
> > the list:
> >
> > I want to know if this is possible:
> >
> > I want to build a network without OSPF/ISIS as IGP. And I
> > dont want to use
> > static. I plan to use iBGP as my routing protocol and the rest via
> > +ACI-directly
> > connected+ACI-
> >
> > the essential idea being that all +ACI-directly conncted+ACI-
> > next-hops will
> > run
> > iBGP among them ......no routing needed as these are directly
> > conncted+ACI-
> > and
> > all +ACI-host end points+ACI- in my network/their
> > networks/customer networks
> > are
> > distributed into my iBGP (relying on split horizon/ non iBGP to iBGP
> > reflection/as you call it..... to prevent too much route
> > distribution to
> > each node).
> >
> > each iBGP node puts itself as the +ACI-next-hop+ACI- for the
> > routes it is
> > advertising.
> >
> > so now, i know to get to network A from network B, lets say
> > the path is
> > B-x-y-z-A, then B network A is known to x via iBGP with next-hop as y
> > interface, y knows to get to z he has to choose that next-hop
> > interface on z
> > and z has A directly connected.
> >
> > my question is this:
> >
> > do the links between x-y and y-z, or rather the interfaces
> > between x-y and
> > y-z need +ACI-unique+ACI- IP addresses?
> >
> > cant i have interface-x-to-y as 10.1.1.1 and interface-y-to-x
> > as 10.1.1.2
> > and interface-y-to-z as 10.1.1.1 and interface-z-to-y as 101.1.2 too?
> >
> > is there a problem with this? rememeber there is no IGP.
> >
> > -rgds
> > Alok
>
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>
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