[j-nsp] policy from JNCIP book

David water dwater2010 at gmail.com
Tue May 4 08:31:22 EDT 2010


Hi,

I am trying to understand the policy in BGP, in JNCIP book we have following
policy with term 1 to 3. Term 1 and 2 is rejecting all unwanted routes and
term 3 is matching those are originating in C1 and reference to the next
policy. So here next policy will be next term (term4) if so then it will be
rejected ? if it is pointing to other policy then it is not define then will
it mach to the BGP default policy to accept all EBGP routes? Please help me
to understand. This policy is used in import at EBGP peer to accept the
selected route.  Same way if I want to match customer prefix route, lets say
1.1.1.0/24 then in term I will use route filter to match the prefix and then
next-policy?

term 1 {
from {
route-filter 0.0.0.0/0 through 0.0.0.0/7 reject;
route-filter 0.0.0.0/1 prefix-length-range /1-/7 reject;
}
}
term 2 {
from {
route-filter 0.0.0.0/0 prefix-length-range /29-/32 reject;
route-filter 172.16.0.0/12 orlonger reject;
route-filter 192.168.0.0/16 orlonger reject;
route-filter 10.0.0.0/8 orlonger reject;
}
}
term 3 {
from as-path c1;
then next policy;
}
term 4 {
then reject;
}


-- 
David W.


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