Re: BGP config.

[Tony Li <[e-mail]>]

Hi,

   sorry to disturb you, I don't know if this list is the correct place
   for such mails, if not please point me to the right place.

As this is a vendor-specific question, the best place to get support
is via your normal support channels.  Since this IS a cisco question,
this is likely to be your local distributor or TAC.

	LAN belonging to AS 111 (ip address: 1.2.3.4)

   Router-1 is the BGP speaker for AS 111 and establish a BGP connection
   with Router-2 which is the BGP speaker of AS 222.

   Router-1 have the following configuration:

	   Router bgp 111
	   network 1.2.3.4

   It seems that router-2 have the following:

	   Router bgp 222
	   network 1.2.3.4

In more recent software, this network command is no longer necessary.

   In this case I presume that we have a conflict. Network 1.2.3.4 cannot
   be originated by 2 ASes. 

It _can_ be done, but there are many good reasons not to do so.

   Following a few set of tests, people have seen correct routing updates
   going from Router-1 to Router-2 but all the updates received by
   Router-1 from Router-2 were received with the UNREACHABLE attribute.
   Unfortunately Router-2 is the service provider router and I do not have
   any access on it.

   If I'm on the right way the routing table of the two routers is
   probably affected. But it concerns only the network 1.2.3.4 route or
   all the routing table is corrupted ?

Can't tell.  Not enough info.

   Anyway, what are the risks and consequences of such configuration ?

At the very worst, the DMZ will be seen as belonging to two different
ASs.  It's possible that hosts on the DMZ would be routed incorrectly.
It may break certain policy filtering that other ASs may be doing.

Tony