From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Tue Apr 25 2006 - 12:14:05 GMT-3
Suppose R6 advertises destination "X" to R2. When R2 goes to send traffic to
X it has to physically transit R3 to reach R6. Since R3 does not have a route
to X it will drop that traffic, hence a black hole. To fix this either run
BGP on R3, redistribute X into an IGP that R3 is running, or tunnel BGP over
R3 via a GRE, IPIP, or MPLS VPN Tunnel.
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
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________________________________
From: nobody@groupstudy.com on behalf of Shamin
Sent: Tue 4/25/2006 10:04 AM
To: Cisco certification
Subject: BGP issue, Unable to understand.
Hi,
<----- R6(AS100) -------RIP------------ R3 ------------OSPF----------
R2(AS200) ----------->
|
I
|___________________EBGP_________________________|
- I am referring to the IEWB VER3.0 , LAB4 ,Task 5.3 .
In the above scenario, R6 and R2 are EBGP peers. But they are connected
through R3 ,who is not running BGP.
The lab reuirements states something about "configure to ensure full
connectivity" . I am sorry I dont have the workbook in front of me now. I
can enter the exact wordings later.
I went through the solution guide, It says as follows:
"In order to provide transit services,it is necessary that all devices in
the transit path have specific (or atleast default path) reachability
information about the prefix in question. In the above case R3 is used as a
transit between As100 and AS200.
However R3 is not running BGP, Therefore from perspective of As200 and
AS100 ,full reachability is possible. However, when packets are send across
the network and reach R3 , they are black holed (dropped) ."
I really did not understand the above statements about this scenario. I hope
someone can clarify this to me.
Thanks for all your inputs.
Regards
shamin
This archive was generated by hypermail 2.1.4 : Mon May 01 2006 - 11:41:59 GMT-3