The syntax may not be exactly correct, but the below gives a rough outline of a
relatively simple setup using communities. You can use a prefix-set or
as-path-set with all the prefixes/asns you advertise to filter outbound to
transit instead of communities (or in addition to), but communities will scale
better in the long run. There may be better ways to do it but this should give
a good start.
--- Apply to customer(s) ---
Route-policy fulltable-out
If destination in bogons then
Drop
elseif community matches-any ( "LOCALPREFIX", "CUSTPREFIX", "PEERPREFIX,
"TRANSITPREFIX" ) then
Pass
Endif
End-policy
Route-policy asCUSTASN-in
If destination in asCUSTASN then
Set community CUSTPFX
Endif
End-policy
Prefix-set asCUSTASN
CUS.PFX.A.0/20 le 24,
CUS.PFX.B.0/24,
Etc...
End-set
--- Apply to Transit ---
Route-policy transit-in
If destination in bogons then
Drop
Else
Set community TRANSITPREFIX
endif
End-policy
Route-policy transit-out
If destination in bogons then
Drop
elseif community matches-any ( "LOCALPREFIX", "CUSTPREFIX" ) then
Pass
endif
End-policy
prefix-set bogons
0.0.0.0/8 le 32,
10.0.0.0/8 le 32,
100.64.0.0/10 le 32,
127.0.0.0/8 le 32,
169.254.0.0/16 le 32,
172.16.0.0/12 le 32,
192.0.0.0/24 le 32,
192.0.2.0/24 le 32,
192.168.0.0/16 le 32,
198.18.0.0/15 le 32,
198.51.100.0/24 le 32,
203.0.113.0/24 le 32,
224.0.0.0/4 le 32,
240.0.0.0/4 le 32,
0.0.0.0/0 ge 25
end-set
-Charles
-----Original Message-----
From: cisco-nsp [mailto:[email protected]] On Behalf Of Carter,
Bill
Sent: Friday, November 6, 2015 10:59 AM
To: [email protected]
Subject: [c-nsp] Sample IOSXR RPL for small ISP
I am setting up a pair of Cisco ASRs for an small ISP. Each ASR has a
connection to an upstream ISP. The ASRs are also connected to downstream
customers with BGP. I am looking for some sample route-policies. The route
policies should prevent the ISP from becoming transit for the entire Internet,
but still be transit for the downstream customers.
Bill Carter
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