Re: [NANOG] peering between ASes

[Matthew Moyle-Croft <mmc () internode com au>]

Nathan Ward wrote:
> If the foreign AS really wants to send you routes that way, they can  
> do it regardless of how you stop your advertisements being accepted by/ 
> reaching them. We're hardly talking high security here.
>
> ip route <prefix> <netmask> 1.1.1.1 works a treat.
>   
I'm not quite sure of your point Nathan.   That'd stop connectivity 
which isn't usually the point - especially if the issue is point (2) below.

MLPAs are disliked for two main reasons that I've been able to discern.

(1) Lack of control

Because of the lack of direct relationships with the other networks you 
can get some fairly odd routing behaviours which gives suboptimal 
performance when you meet at multiple MLPAs in a theatre - leading to 
difficulty in doing traffic engineering.   From traffic flows, to 
wierdness caused by people advertising prefixes inconsistently to 
transit and peering and blaming IOS bugs for it <sigh>.

(2)  Transit customers using an MLPA to "not pay" for traffic to your 
network

A fair point - but, if they weren't a customer then you might be paying 
to get their traffic or they would be sending it that way anyway.  

MMC



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