[c-nsp] Sample IOSXR RPL for small ISP

[Charles Monson]

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:cisco-nsp-bounces at puck.nether.net] On Behalf Of Carter, Bill
Sent: Friday, November 6, 2015 10:59 AM
To: cisco-nsp at puck.nether.net
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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