[j-nsp] Policy Statement Question

[Jeff Neuffer]

We do "AS_PATH prepending" by matching our prefix's with a "from{}" and 
"then{}".  I haven't tried it any other way.  So I would export this in 
the eBGP session to the peer I wanted to influence.


protocols {
    bgp {
        group provider1 {
            type external;          
            multihop {
                ttl 2;
            }
            export bgp-prefix-stuff;
            neighbor xxx.xxx.xxx.xxx {
                peer-as 1111;
            }
        }
  }
}

policy-options {

...omit...

policy-statement bgp-prefix-stuff {

        ...omit...

        term bgp-prefix-stuff {
            from {
                protocol bgp;
                policy our_prefixes;
            }
            then accept;
        }
        then reject;
    }

policy-statement our_prefixes {
        term our_prefixes {
            from {
                route-filter xxx.xxx.xxx.0/19 exact;
                inactive: route-filter xxx.xxx.xxx.0/20 exact;
            }
            then accept;
        }

        ...omit...

        term our_prefixes_prepend {
            from {
                route-filter xxx.xxx.xxx.0/20 exact;
            }
            then {
                as-path-prepend "9999 9999 9999";
                accept;
            }
        }
        then reject;
    }
}

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Chris Davies wrote:
> I have two current issues which might have one solution.  Our initial 
> testing shows that the Juniper reduced average latency about 10ms, so, 
> even though our Cisco wasn't showing any real signs of cpu usage, it 
> appears (and feels like) the Juniper has made an improvement in 
> performance which was a small surprise.
>
> The issue I'm working with now is that we buy transit from two 
> providers, a Tier 1 (Cogent) and a Tier 2 (Internap) if you wanted to 
> use 'old' terms.  The problem I am running into is that since Internap 
> is technically a Tier 2 (they buy transit from Tier 1 providers), only 
> 25k of the 175k routes have shorter ASPaths to the destination.
>
> Since Internap is only adding 1 router hop and 1 AS Hop, I should ASPad 
> on Cogent's side.  That would perhaps level the playing field for 
> inbound traffic.
>
> If I understand this right, can someone do a sanity check?  (The 
> IOS2junos convertor really made things a mess for me, so, I tried to 
> figure out what it needed and stripped out the rest of it)
>
> policy-statement aspad_Cogent {
>      term aspad_Cogent {
>          then as-path-prepend 11110;
>      }
> }
>
> Do I need a from condition if I want to unconditionally aspad?
>
> If I understand it, I do not want an accept here since I want the next 
> policy statement to also be executed.
>
> Now, on my A-Peer with Cogent (they use multihop), I would set
>
> export [ aspad_Cogent bgp_distributes ]
>
> At that point, I need to
>
> clear bgp neighbor (a-peer's ip) soft
>
> to send the config.
>
> AS Padding on my exports should result in inbound traffic perhaps 
> choosing a better path since the ASPath's across Cogent and Internap 
> would be a little more balanced.  When I add another provider alongside 
> these two, if it is another Tier 1 provider, I would probably need to 
> pad their incoming as well.
>
> If someone could give this a quick sanity check, I'd appreciate it.  12 
> years of IOS -> Junos has been a bit of a challenge.  :)
>
> Thanks.
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