I've found there are many providers that have completely disconnected autonomous systems. For example Yipes (6517) uses L3 on the west coast and Williams on the east coast. 66.7.129.0/24 is advertised under their AS through WCG and 209.213.209.0/24 is advertised under their AS through L3. And the number of connected autonomous systems with de-aggregated prefixes appears to be even more common than a disconnected AS. It would seem that many (most?) network operators are just ignoring the more vocal opinions on NANOG. -Ralph
RD> Date: Wed, 13 Nov 2002 14:46:05 -0500 (EST) RD> From: Ralph Doncaster RD> And the number of connected autonomous systems with RD> de-aggregated prefixes appears to be even more common than a RD> disconnected AS. I see many weed-filled yards. Must mean weeds are acceptable, even desirable, plants. Eddy -- Brotsman & Dreger, Inc. - EverQuick Internet Division Bandwidth, consulting, e-commerce, hosting, and network building Phone: +1 (785) 865-5885 Lawrence and [inter]national Phone: +1 (316) 794-8922 Wichita ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Date: Mon, 21 May 2001 11:23:58 +0000 (GMT) From: A Trap <blacklist@brics.com> To: blacklist@brics.com Subject: Please ignore this portion of my mail signature. These last few lines are a trap for address-harvesting spambots. Do NOT send mail to <blacklist@brics.com>, or you are likely to be blocked.
Depends on which weed:). On Wed, 13 Nov 2002, E.B. Dreger wrote:
RD> Date: Wed, 13 Nov 2002 14:46:05 -0500 (EST) RD> From: Ralph Doncaster
RD> And the number of connected autonomous systems with RD> de-aggregated prefixes appears to be even more common than a RD> disconnected AS.
I see many weed-filled yards. Must mean weeds are acceptable, even desirable, plants.
Eddy -- Brotsman & Dreger, Inc. - EverQuick Internet Division Bandwidth, consulting, e-commerce, hosting, and network building Phone: +1 (785) 865-5885 Lawrence and [inter]national Phone: +1 (316) 794-8922 Wichita
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Date: Mon, 21 May 2001 11:23:58 +0000 (GMT) From: A Trap <blacklist@brics.com> To: blacklist@brics.com Subject: Please ignore this portion of my mail signature.
These last few lines are a trap for address-harvesting spambots. Do NOT send mail to <blacklist@brics.com>, or you are likely to be blocked.
There is a significant difference between not aggregating, and using discontiguous-AS EBGP. As long as you are familiar with the pitfalls, there is nothing inherently wrong with using a single AS in multiple locations, and advertising discrete blocks of address space in each one. The best reason to do this is for a network that you eventually plan to merge - it eliminates issues of having to make major BGP configuration changes. Of course, it required you to point default routes out your upstreams, as you will not see the prefixes from one discontiguous island, in another, thanks to BGP loop detection. Several large access ISPs have run in the fashion for extended periods. As far as aggregation - they are a couple reasons to not aggregate, but the vast majority of it is sloth. Finally, in regard to "vocal opinions on NANOG" - well, anyone who has read NANOG for a while knows that vocal isn't always correct. - Daniel Golding On Wed, 13 Nov 2002, Ralph Doncaster wrote:
I've found there are many providers that have completely disconnected autonomous systems. For example Yipes (6517) uses L3 on the west coast and Williams on the east coast. 66.7.129.0/24 is advertised under their AS through WCG and 209.213.209.0/24 is advertised under their AS through L3.
And the number of connected autonomous systems with de-aggregated prefixes appears to be even more common than a disconnected AS.
It would seem that many (most?) network operators are just ignoring the more vocal opinions on NANOG.
-Ralph
On Wed, Nov 13, 2002 at 02:28:07PM -0600, Daniel Golding wrote:
As long as you are familiar with the pitfalls, there is nothing inherently wrong with using a single AS in multiple locations, and advertising discrete blocks of address space in each one. The best reason to do this is for a network that you eventually plan to merge - it eliminates issues of having to make major BGP configuration changes.
Nothing inherently wrong with it if you're paying for transit, but good luck getting peering in multiple locations without presenting consistent views. Just making sure Ralph knows this, since I'm sure achieving 99% peering by getting 10GE into NYIIX is the goal for his OC192 over 2600 network. :) -- Richard A Steenbergen <ras@e-gerbil.net> http://www.e-gerbil.net/ras PGP Key ID: 0x138EA177 (67 29 D7 BC E8 18 3E DA B2 46 B3 D8 14 36 FE B6)
On Wed, 13 Nov 2002, Richard A Steenbergen wrote:
Just making sure Ralph knows this, since I'm sure achieving 99% peering by getting 10GE into NYIIX is the goal for his OC192 over 2600 network. :)
Trying to run OC192 over a 2600 router would make more business sense than giving away 250mbps of free transit, which you claim to have done (on isp-bandwidth) lately. ;-) -Ralph
On Wed, Nov 13, 2002 at 03:49:53PM -0500, Ralph Doncaster wrote:
On Wed, 13 Nov 2002, Richard A Steenbergen wrote:
Just making sure Ralph knows this, since I'm sure achieving 99% peering by getting 10GE into NYIIX is the goal for his OC192 over 2600 network. :)
Trying to run OC192 over a 2600 router would make more business sense than giving away 250mbps of free transit, which you claim to have done (on isp-bandwidth) lately. ;-)
Please note the difference between "giving away" and "this guy doesn't pay".
I've never seen anyone here complain that Yipes de-aggregates 66.7.128.0/18 into /24's like 66.7.129.0/24. Until the bigger providers change their ways why should someone like me (who has only chopped a /20 into /21-/23 with a covering /20) decide that doing a single aggregate /20 announcement is going to make a difference?
First of all I've never seen anyone point to Yipes as an example of how to do anything correctly or successfully. Secondly, if you REALLY need to do it, you can probably get away with it. But if you have any kind of decency and a common transit provider, announce the aggregate and the more specifics with no-export. It's not required, but it's what nice/smart people do. Just because someone else litters doesn't mean you should too. -- Richard A Steenbergen <ras@e-gerbil.net> http://www.e-gerbil.net/ras PGP Key ID: 0x138EA177 (67 29 D7 BC E8 18 3E DA B2 46 B3 D8 14 36 FE B6)
inherently wrong with using a single AS in multiple locations, and advertising discrete blocks of address space in each one. The best reason to do this is for a network that you eventually plan to merge - it eliminates issues of having to make major BGP configuration changes.
Nothing inherently wrong with it if you're paying for transit, but good luck getting peering in multiple locations without presenting consistent views.
No problem at all. Use a tunnel. Going back to the original question: (A) Is there a reason have disconnected ASs? Sure. Does it make more sense than using multiple AS numbers? No. (B) Is there a reason to deaggregate? Absolutely. The biggest being rather bad internal allocations practiced by networks. Alex --
Aren't some reasons for using disconnected as's regulatory based ie the bells etc? On Wed, 13 Nov 2002 alex@yuriev.com wrote:
inherently wrong with using a single AS in multiple locations, and advertising discrete blocks of address space in each one. The best reason to do this is for a network that you eventually plan to merge - it eliminates issues of having to make major BGP configuration changes.
Nothing inherently wrong with it if you're paying for transit, but good luck getting peering in multiple locations without presenting consistent views.
No problem at all. Use a tunnel.
Going back to the original question:
(A) Is there a reason have disconnected ASs? Sure. Does it make more sense than using multiple AS numbers? No.
(B) Is there a reason to deaggregate? Absolutely. The biggest being rather bad internal allocations practiced by networks.
Alex
--
Actually, most of the RBOC/ILEC's use completely seperate AS's. "FCC Regulation" being a legitimate reason to request a whole bushel of AS's from ARIN. Try doing an ARIN whois on bellsouth, and you get... Bellsouth.Net (AS7891) BELLSOUTH-NET-BLK2 7891 - 7894 Bellsouth.Net (AS8060) BELLSOUTH-NET-BLK3 8060 - 8063 BellSouth.net Inc. (AS6380) BELLSOUTH-NET-BLK 6380 - 6389 - Dan On Wed, 13 Nov 2002, Scott Granados wrote:
Aren't some reasons for using disconnected as's regulatory based ie the bells etc?
On Wed, 13 Nov 2002 alex@yuriev.com wrote:
inherently wrong with using a single AS in multiple locations, and advertising discrete blocks of address space in each one. The best reason to do this is for a network that you eventually plan to merge - it eliminates issues of having to make major BGP configuration changes.
Nothing inherently wrong with it if you're paying for transit, but good luck getting peering in multiple locations without presenting consistent views.
No problem at all. Use a tunnel.
Going back to the original question:
(A) Is there a reason have disconnected ASs? Sure. Does it make more sense than using multiple AS numbers? No.
(B) Is there a reason to deaggregate? Absolutely. The biggest being rather bad internal allocations practiced by networks.
Alex
--
ASN per LATA to abide by the Telco Act of 1996... SBC is rapidly shrinking the need down to a handful. 4 ASNs are in use at IXs today. Next year that should be cut in half. http://www.sbcbackbone.net/peering/ -ren At 03:14 PM 11/13/2002 -0600, Daniel Golding wrote:
Actually, most of the RBOC/ILEC's use completely seperate AS's. "FCC Regulation" being a legitimate reason to request a whole bushel of AS's from ARIN.
Try doing an ARIN whois on bellsouth, and you get...
Bellsouth.Net (AS7891) BELLSOUTH-NET-BLK2 7891 - 7894 Bellsouth.Net (AS8060) BELLSOUTH-NET-BLK3 8060 - 8063 BellSouth.net Inc. (AS6380) BELLSOUTH-NET-BLK 6380 - 6389
- Dan
On Wed, 13 Nov 2002, Scott Granados wrote:
Aren't some reasons for using disconnected as's regulatory based ie the bells etc?
On Wed, 13 Nov 2002 alex@yuriev.com wrote:
inherently wrong with using a single AS in multiple locations, and advertising discrete blocks of address space in each one. The
best reason
to do this is for a network that you eventually plan to merge - it eliminates issues of having to make major BGP configuration changes.
Nothing inherently wrong with it if you're paying for transit, but good luck getting peering in multiple locations without presenting consistent views.
No problem at all. Use a tunnel.
Going back to the original question:
(A) Is there a reason have disconnected ASs? Sure. Does it make more sense than using multiple AS numbers? No.
(B) Is there a reason to deaggregate? Absolutely. The biggest being rather bad internal allocations practiced by networks.
Alex
--
DG> Date: Wed, 13 Nov 2002 14:28:07 -0600 (CST) DG> From: Daniel Golding DG> Of course, it required you to point default routes out your DG> upstreams, as you will not see the prefixes from one DG> discontiguous island, in another, thanks to BGP loop DG> detection. router bgp <asn> neighbor <w.x.y.z> allowas-in Eddy -- Brotsman & Dreger, Inc. - EverQuick Internet Division Bandwidth, consulting, e-commerce, hosting, and network building Phone: +1 (785) 865-5885 Lawrence and [inter]national Phone: +1 (316) 794-8922 Wichita ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Date: Mon, 21 May 2001 11:23:58 +0000 (GMT) From: A Trap <blacklist@brics.com> To: blacklist@brics.com Subject: Please ignore this portion of my mail signature. These last few lines are a trap for address-harvesting spambots. Do NOT send mail to <blacklist@brics.com>, or you are likely to be blocked.
On Wed, 13 Nov 2002, Daniel Golding wrote: [...]
As far as aggregation - they are a couple reasons to not aggregate, but the vast majority of it is sloth. [...]
I've never seen anyone here complain that Yipes de-aggregates 66.7.128.0/18 into /24's like 66.7.129.0/24. Until the bigger providers change their ways why should someone like me (who has only chopped a /20 into /21-/23 with a covering /20) decide that doing a single aggregate /20 announcement is going to make a difference? -Ralph
Of course, it required you to point default routes out your upstreams, as you will not see the prefixes from one discontiguous island, in another, thanks to BGP loop detection.
ouch. bad practice defaulting like that, however to static route your individual blocks wouldnt be a problem
Several large access ISPs have run in the fashion for extended periods.
whats the opposite of autonomous? dependent? so AS becomes DS? :) seriously tho, if an AS ceases to be autonomous then theres little point in having them and you may as well do global routing on prefixes with a hop count hmm can RIP handle 120000 routes?
As far as aggregation - they are a couple reasons to not aggregate, but the vast majority of it is sloth.
like to meet C&W peering policy etc? the only valid reasons imho are traffic engineering and customer multihoming
Finally, in regard to "vocal opinions on NANOG" - well, anyone who has read NANOG for a while knows that vocal isn't always correct.
altho it gives an indication of best practice and therefore policy and like the other thread on filtering RIR allocation boundaries, sure you can go and do your own thing but dont complain when providers start filtering your routes and ignoring your prefixes! Steve
- Daniel Golding
On Wed, 13 Nov 2002, Ralph Doncaster wrote:
I've found there are many providers that have completely disconnected autonomous systems. For example Yipes (6517) uses L3 on the west coast and Williams on the east coast. 66.7.129.0/24 is advertised under their AS through WCG and 209.213.209.0/24 is advertised under their AS through L3.
And the number of connected autonomous systems with de-aggregated prefixes appears to be even more common than a disconnected AS.
It would seem that many (most?) network operators are just ignoring the more vocal opinions on NANOG.
-Ralph
I suppose that depends on how many static routes you would need, and how many routers you would have to touch. If you have 10 sites like this, and add or remove several blocks every day (an extreme, of course), then you could end up manipulating many statics on numerous routers, which, aside from being a waste of engineer time, can lead to fat-finger mistakes. Since when did default routing become bad form, on a transit-buying network? - Daniel Golding On Wed, 13 Nov 2002, Stephen J. Wilcox wrote:
Of course, it required you to point default routes out your upstreams, as you will not see the prefixes from one discontiguous island, in another, thanks to BGP loop detection.
ouch. bad practice defaulting like that, however to static route your individual blocks wouldnt be a problem
On Wed, 13 Nov 2002, Daniel Golding wrote:
I suppose that depends on how many static routes you would need, and how many routers you would have to touch.
If you have 10 sites like this, and add or remove several blocks every day (an extreme, of course), then you could end up manipulating many statics on numerous routers, which, aside from being a waste of engineer time, can lead to fat-finger mistakes.
this is a hack whichever way you look at it.. just that its better than a default and acheives a result more like the contigous AS would have had than an end user network.. hmm i wonder if this would work if you ibgp peer your discontigous border routers and use a route-map to make sure the routes point at your upsteam - would remove the statics and your manual engineering issues. argh what am i saying.. now i'm promoting this setup!
Since when did default routing become bad form, on a transit-buying network?
if you are a proper ISP with a full routing table you dont need a default and having one merely sends junk to your upstream, i guess thats chargeable so maybe they think its a good thing but it doesnt really fit with the various nanog threads on tidying up bogon packets as they hop around the net. Steve
- Daniel Golding
On Wed, 13 Nov 2002, Stephen J. Wilcox wrote:
Of course, it required you to point default routes out your upstreams, as you will not see the prefixes from one discontiguous island, in another, thanks to BGP loop detection.
ouch. bad practice defaulting like that, however to static route your individual blocks wouldnt be a problem
On Wed, Nov 13, 2002 at 08:46:07PM +0000, Stephen J. Wilcox wrote:
As far as aggregation - they are a couple reasons to not aggregate, but the vast majority of it is sloth.
like to meet C&W peering policy etc?
http://www1.cw.com/template_05.jsp?ID=peer_03 "aggregation is encouraged, and considered in this parameter" Regards, Daniel
thats new, looks like they amended it! On Sat, 16 Nov 2002, Daniel Roesen wrote:
On Wed, Nov 13, 2002 at 08:46:07PM +0000, Stephen J. Wilcox wrote:
As far as aggregation - they are a couple reasons to not aggregate, but the vast majority of it is sloth.
like to meet C&W peering policy etc?
http://www1.cw.com/template_05.jsp?ID=peer_03
"aggregation is encouraged, and considered in this parameter"
Regards, Daniel
I don't know how much of it is ignorance, or resource constraints. I've worked with companies that have used disconnected AS's because they couldn't justify multiple AS's and they needed to multihome in multiple isolated locations. I've also worked with companies that deliberately de-aggregate prefixes due to link capacity issues. Network operators have to balance building an ideal network to what equipment, links, IPs and AS's they can justify. I personally rather see network operators de-aggregate and utilize space efficiently as opposed to hoarding larger prefixes to make their network appear like something it isn't. -Adam -----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu]On Behalf Of Ralph Doncaster Sent: Wednesday, November 13, 2002 11:46 AM To: nanog@merit.edu Subject: disconnected autonomous systems I've found there are many providers that have completely disconnected autonomous systems. For example Yipes (6517) uses L3 on the west coast and Williams on the east coast. 66.7.129.0/24 is advertised under their AS through WCG and 209.213.209.0/24 is advertised under their AS through L3. And the number of connected autonomous systems with de-aggregated prefixes appears to be even more common than a disconnected AS. It would seem that many (most?) network operators are just ignoring the more vocal opinions on NANOG. -Ralph
participants (10)
-
Adam Bechtel -
alex＠yuriev.com -
Daniel Golding -
Daniel Roesen -
E.B. Dreger -
Ralph Doncaster -
ren -
Richard A Steenbergen -
Scott Granados -
Stephen J. Wilcox