From: kumara.shunmugam@wipro.com
Date: Thu Jul 28 2005 - 10:21:00 GMT-3
The question was to block the traffic which is transit thru AS100 to AS54's CUSTOMERS... That means , it is assumed that you have some other ASes connected behind to AS54 (AS50,AS60 I think) ,hence you should block all the prefixes which are not originated in AS54(originated in AS54's customer network) ... However, the prefixes originated in AS54 can come inside ..This way your AS200 will not use AS100 to reach AS54's CUSTOMERS
Hope this clarifies
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Quetta Walla
Sent: Thursday, July 28, 2005 5:51 AM
To: ccielab@groupstudy.com
Subject: can some one explain IE vol1 lab4 task 6.5
Hello,
This task says AS 100's corporate policy dictates it should not provide transit to get to any of AS 54 customers.
r6 is in AS 100 and r2 is in AS 200 with loop0 ip of 150.1.2.2
r6#
router bgp 100
nei 150.1.2.2 remote-as 200
nei 150.1.2.2 filter-list 1 out
!
ip as-path access-list 1 permit _54$
But r2 in AS 200 still shows AS path 100 54 for routes of AS 54
Should'nt it be:
ip as-path access-list 1 deny _54_
ip as-path access-list 1 permit .*
->means match as-path 54 any where in as-path and deny. This way as-path 100 54 will not be matched and AS 100 will not become transit for traffic from AS 200 to AS 54.
The task does not allow use of comminities, IP access-list, or prefix-list.
Any comments....will be appreciated.
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