--- On Tue, 1/13/09, Patrick W. Gilmore <patrick@ianai.net> wrote:
AS_PATH != identity, and I would not recommend loading the latter onto the former.
We disagree. When I am researching something, I frequently look at ASNs in the path to figure out not just where but who controls the path.
Oh, I certainly think that there is a loose coupling there, and the relationship is highly valuable from a troubleshooting point of view. However, I would counsel anyone investigating AS_Path relationships to remember that do not completely characterize the relationship between any two organizations, let alone the multipolar relationships between all organizations. It's a good first-cut, but it doesn't have the level of authority that you're implying. I'm not aware of any ASNs being trademarked...
Personally, I would be upset if someone injected a route with my ASN in the AS_PATH without my permission.
Why? Is this a theoretical "because it's ugly" complaint, or is there a reason why manipulating this particular BGP attribute in this particular way is so bad? Organizations do filtering and routing manipulation all over the place. Is there something worse about doing it this way than others?
Filtering and other manipulation happened on your router, prepending my ASN is putting that information into every router. That seems to be a serious qualitative difference to me. Do you disagree?
This is qualitatively similar to an ASN announcing de-aggregated routes - it may be nice if they don't, and you don't have to accept them, but are they permitted?
This thread has been interesting & educational. So many people seem to be happy to explain why they should be allowed to use globally unique identifiers they do not own in ways which were not intended, then explain to the people who do own those identifiers how they should react, which alarms should go off, and even which priority the alarms should have.
As I have repeated probably hundreds of times: Your network, your decision. I have yet to hear a credible argument against that stance. What you do _inside_ your network is _your_ decision. When it leaves your network, however, things change.
Exactly! Provider RB announces $WEIRD. A bunch of providers receive alarms about the existence of $WEIRD, and they treated this as $IMPORTANT. The bunch of providers who treated this as $IMPORTANT are informing all of us about their monitoring thresholds and their responses to this threshold being met. Their networks, their decisions. It should be pointed out that pre-provisioned AS_Path filters and prefix-lists would actually be effective at defeating this and preventing someone who is actually malicious from using this technique. This is an excellent argument for implementing SIDR...
Announcing an ASN which is not yours to eBGP peers means it is leaving your network, which means it is not just your business. Doing so and then telling the ASN owner that they should not worry about it afterwards - and in fact arguing when the owner repeatedly tells you this caused them problems - does not seem to be the proper course of action.
Understood, but if this is viewed as problematic, there is a very simple solution: don't allow a BGP customer (or peer!) to prepend someone else's ASN.
I mentioned earlier in the thread if Cogent prepending Sprint's ASN to Verio, people would react differently. Randy said tools can be used for good or bad, obviously implying he's the good guy. He is not the good guy. He used someone else's resources without their permission and without even notifying them, costing them time & effort. Randy doesn't get to decide if the ASN owner should have alerted or investigated or whatever, and neither do any of you unless it is your ASN.
How can anyone seriously argue the ASN owner is somehow wrong and keep a straight face? How can anyone else who actually runs a network not see that as ridiculous?
Are any providers going to implement ^ASN filtering as a result of this experiment? This could turn out to be a very inexpensive lesson, which is far preferable to more expensive lessons... David Barak Need Geek Rock? Try The Franchise: http://www.listentothefranchise.com