nanog mailing list archives
Re: Order of ASes in the BGP Path
From: "Stephen J. Wilcox" <steve () telecomplete co uk>
Date: Mon, 29 Aug 2005 21:20:01 +0100 (BST)
On Mon, 29 Aug 2005, Abhishek Verma wrote:
Hi, Is the order of AS numbers (except for perhaps the first one which denotes the AS the route was originated from) in the AS_PATH in BGP important? In fact, does anybody even care for the first AS number that appears in the Path? AFAIK, AS numbers in the BGP serves two purposes. It helps in loop detection and it helps us count the AS Path length. If this is the case then the order should not really matter much. My question is that whether the operators care if the order, for some reason changes? Eg. Legend: {} denotes the sequence, while [] denotes the set Path {1 2} [3 4] {5} Would somebody mind if this was represented as {1 2 5} [3 4] ?
I'd mind, I value the predictability and ability to understand how a bgp path arrives into my network. Fiddling with this kind of thing is quite similar to spoofing in some ways, particularly that I can see fabricating the as-path could be used to confuse folks tracing announcements, perhaps I'm missing the positive use for this. As no one has asked yet, allow me.. what are you trying to do? Steve
Current thread:
- Re: Order of ASes in the BGP Path, (continued)
- Re: Order of ASes in the BGP Path Abhishek Verma (Aug 29)
- Re: Order of ASes in the BGP Path Stephen J. Wilcox (Aug 30)
- Re: Order of ASes in the BGP Path Jake Khuon (Aug 30)
- Bellsouth.net Outage? Alan Spicer (Aug 30)
- Re: Bellsouth.net Outage? Jon Lewis (Aug 30)
- Re: Order of ASes in the BGP Path Randy Bush (Aug 29)
- Re: Order of ASes in the BGP Path Tom Sanders (Aug 29)
- Re: Order of ASes in the BGP Path Paul Jakma (Aug 29)
- Re: Order of ASes in the BGP Path Abhishek Verma (Aug 30)
- Re: Order of ASes in the BGP Path Paul Jakma (Aug 29)
- Re: Order of ASes in the BGP Path Tom Sanders (Aug 29)