Hello NANOG, I noticed that more than 3K prefixes are with 2 Origin ASes. Are they the simplest cases of anycast? Or they are mainly due to misconfiguration? --- --Zhenkai
On 22/04/2009, at 6:53 PM, Zhenkai Zhu wrote:
Hello NANOG,
I noticed that more than 3K prefixes are with 2 Origin ASes. Are they the simplest cases of anycast? Or they are mainly due to misconfiguration?
The third (and probably more likely) option is that the prefixes are advertised by two providers as the customer wants redundancy with their own IP space, but does not have a public ASN. Ie. the customer has a circuit and possibly a BGP feed to two different providers. -- Nathan Ward
Ah, that's very possible. So I suppose the 90 prefixes with 3 origin ASes are due to the same reason.. Then there is basically no inter-As anycast besides the anycast prefix for DNS root, since I only noticed like 8 prefixes that are announced by more than 3 ASes.. ---- --Zhenkai Nathan Ward wrote:
On 22/04/2009, at 6:53 PM, Zhenkai Zhu wrote:
Hello NANOG,
I noticed that more than 3K prefixes are with 2 Origin ASes. Are they the simplest cases of anycast? Or they are mainly due to misconfiguration?
The third (and probably more likely) option is that the prefixes are advertised by two providers as the customer wants redundancy with their own IP space, but does not have a public ASN. Ie. the customer has a circuit and possibly a BGP feed to two different providers.
-- Nathan Ward
On Apr 22, 2009, at 12:12 AM, Zhenkai Zhu wrote:
Ah, that's very possible. So I suppose the 90 prefixes with 3 origin ASes are due to the same reason..
Then there is basically no inter-As anycast besides the anycast prefix for DNS root, since I only noticed like 8 prefixes that are announced by more than 3 ASes..
There's lots of strangeness out there, for instance: http://www.ep.net/policy.html Bill lets anyone who has an IP assignment from an ep.net /24 announce that /24. The term 'anycast' has some vagueness at the edges. Kris
On 22/04/2009, at 7:12 PM, Zhenkai Zhu wrote:
Ah, that's very possible. So I suppose the 90 prefixes with 3 origin ASes are due to the same reason..
Then there is basically no inter-As anycast besides the anycast prefix for DNS root, since I only noticed like 8 prefixes that are announced by more than 3 ASes..
I never said that was the only reason, I'm sure plenty of people are doing anycast with different originating ASes. For example, check the 192.88.99.0/24 prefix. -- Nathan Ward
Zhenkai Zhu wrote:
Then there is basically no inter-As anycast besides the anycast prefix for DNS root, since I only noticed like 8 prefixes that are announced by more than 3 ASes..
I presume you are using route-views or some such to get a larger picture of the BGP geography? I believe that many anycasts utilize the same ASN for their anycasted address space. I would expect that a few of them have an ASN specifically for their anycasted space. Given that the networks are duplicates, there's no requirement that one part of the AS needs to receive routes from the other part of the AS. For management and such of the devices, I presume there are separate netblocks advertised with a different ASN (possibly even statically assigned by a hosting network). Jack
-----Original Message----- From: Jack Bates [mailto:jbates@brightok.net]
Given that the networks are duplicates, there's no requirement that one part of the AS needs to receive routes from the other part of the AS. For management and such of the devices, I presume there are separate netblocks advertised with a different ASN (possibly even statically assigned by a hosting network).
Or you could just allow as-loops... not saying it's a good thing, but it could be done ;) Stefan Fouant
Jack Bates wrote:
Zhenkai Zhu wrote:
Then there is basically no inter-As anycast besides the anycast prefix for DNS root, since I only noticed like 8 prefixes that are announced by more than 3 ASes..
I presume you are using route-views or some such to get a larger picture of the BGP geography?
Yes.
I believe that many anycasts utilize the same ASN for their anycasted address space. I would expect that a few of them have an ASN specifically for their anycasted space.
Given that the networks are duplicates, there's no requirement that one part of the AS needs to receive routes from the other part of the AS. For management and such of the devices, I presume there are separate netblocks advertised with a different ASN (possibly even statically assigned by a hosting network).
I just want to make sure if I understand correctly. You mean that the anycasted address space can be announced in different places yet with the same origin AS? Zhenkai
Jack
On Apr 22, 2009, at 4:35 PM, Jack Bates wrote:
Zhenkai Zhu wrote:
I just want to make sure if I understand correctly. You mean that the anycasted address space can be announced in different places yet with the same origin AS?
Yes, and it is commonly done.
I was under the impression anycast services with homogeneous origin AS was far more common than the heterogeneous. Almost all the instances I know of use homogeneous origin AS. I'd be interested in statistics either way. -- TTFN, patrick
Patrick W. Gilmore wrote:
I was under the impression anycast services with homogeneous origin AS was far more common than the heterogeneous. Almost all the instances I know of use homogeneous origin AS.
I'd be interested in statistics either way.
The original question provides a good statistic, I think. Only 8 prefixes that were announced by more than 3 origin AS. Jack
On Wed, Apr 22, 2009 at 04:13:38PM -0500, Jack Bates wrote: [snip]
The original question provides a good statistic, I think. Only 8 prefixes that were announced by more than 3 origin AS.
And the overall message is that only the (prefix holder|originating ASn[s]) can tell you if it is intended or not. Sadly, this is not a useful metric for a third-party to use to determine prefix annoucnement legitimacy. Perhaps an update to RPSL to allow for intentional multiple origins is overdue? [insert thread about folks who do/don't use tools regardless of appropriateness] -- RSUC / GweepNet / Spunk / FnB / Usenix / SAGE
Joe Provo wrote:
And the overall message is that only the (prefix holder|originating ASn[s]) can tell you if it is intended or not. Sadly, this is not a useful metric for a third-party to use to determine prefix annoucnement legitimacy. Perhaps an update to RPSL to allow for intentional multiple origins is overdue?
Legitimacy no, but it does lead one to believe that most anycast (given
3 locations) is homogeneous. I would love multiple origin support.
Jack
On Apr 22, 2009, at 5:48 PM, Jack Bates wrote:
Joe Provo wrote:
And the overall message is that only the (prefix holder|originating ASn[s]) can tell you if it is intended or not. Sadly, this is not a useful metric for a third-party to use to determine prefix annoucnement legitimacy. Perhaps an update to RPSL to allow for intentional multiple origins is overdue?
Legitimacy no, but it does lead one to believe that most anycast (given > 3 locations) is homogeneous. I would love multiple origin support.
There are tons which have 2 origin ASes. I realize that's not a lot of locations by today's anycast standards, but it is probably still common. OTOH: "Serious" anycast obviously requires more than 2, so I grant your point. The overwhelming majority of anycast is done from homogeneous origin AS. Which means I was right. :) -- TTFN, patrick
Patrick W. Gilmore wrote:
On Apr 22, 2009, at 4:35 PM, Jack Bates wrote:
Zhenkai Zhu wrote:
I just want to make sure if I understand correctly. You mean that the anycasted address space can be announced in different places yet with the same origin AS?
Yes, and it is commonly done.
I was under the impression anycast services with homogeneous origin AS was far more common than the heterogeneous. Almost all the instances I know of use homogeneous origin AS.
I'd be interested in statistics either way.
192.88.99.0/24, 2002::/16, and 2001::/32 are some notable examples of heterogeneous origin AS. - Kevin
Kevin Loch wrote:
Patrick W. Gilmore wrote:
On Apr 22, 2009, at 4:35 PM, Jack Bates wrote:
Zhenkai Zhu wrote:
I just want to make sure if I understand correctly. You mean that the anycasted address space can be announced in different places yet with the same origin AS?
Yes, and it is commonly done.
I was under the impression anycast services with homogeneous origin AS was far more common than the heterogeneous. Almost all the instances I know of use homogeneous origin AS.
I'd be interested in statistics either way.
192.88.99.0/24, 2002::/16, and 2001::/32 are some notable examples of heterogeneous origin AS.
And those prefixes (6to4 & Teredo) all come with annoying problems as one never knows which relay is really being used and it is hard to debug how the packets really flow. Greets, Jeroen
192.88.99.0/24, 2002::/16, and 2001::/32 are some notable examples of heterogeneous origin AS.
And those prefixes (6to4 & Teredo) all come with annoying problems as one never knows which relay is really being used and it is hard to debug how the packets really flow.
I agree entirely. As a one of 6to4 relay operator (AS38646), I believe coordination among 6to4 and Teredo operators is needed. Does anyone know is there any operators group who are using 192.88.99.0/24, 2002::/16, and 2001::/32? --- No caffeine, No work. Shin SHIRAHATA <shin@shirahata.name> / <true@sfc.wide.ad.jp>
Shin SHIRAHATA wrote:
192.88.99.0/24, 2002::/16, and 2001::/32 are some notable examples of heterogeneous origin AS. And those prefixes (6to4 & Teredo) all come with annoying problems as one never knows which relay is really being used and it is hard to debug how the packets really flow.
I agree entirely.
As a one of 6to4 relay operator (AS38646), I believe coordination among 6to4 and Teredo operators is needed.
Does anyone know is there any operators group who are using 192.88.99.0/24, 2002::/16, and 2001::/32?
See http://lists.cluenet.de/pipermail/ipv6-ops/ Next to that: whois -h whois.ripe.net RFC3068-MNT that at at least should give you all the European 6to4 operators directly. Greets, Jeroen (RPSL is a nice thing isn't it ;)
Shin SHIRAHATA wrote:
192.88.99.0/24, 2002::/16, and 2001::/32 are some notable examples of heterogeneous origin AS. And those prefixes (6to4 & Teredo) all come with annoying problems as one never knows which relay is really being used and it is hard to debug how the packets really flow.
I agree entirely.
As a one of 6to4 relay operator (AS38646), I believe coordination among 6to4 and Teredo operators is needed.
Does anyone know is there any operators group who are using 192.88.99.0/24, 2002::/16, and 2001::/32?
Next to that: whois -h whois.ripe.net RFC3068-MNT that at at least should give you all the European 6to4 operators directly.
Thank you for you information :) RFC3068-MNT is very interesting. Can non-Europian operator register this mainter object? If not, similar system in other region? Cheers, Shin --- No caffeine, No work. Shin SHIRAHATA <shin@shirahata.name> / <true@sfc.wide.ad.jp>
On Apr 22, 2009, at 5:23 PM, Kevin Loch wrote:
Patrick W. Gilmore wrote:
On Apr 22, 2009, at 4:35 PM, Jack Bates wrote:
Zhenkai Zhu wrote:
I just want to make sure if I understand correctly. You mean that the anycasted address space can be announced in different places yet with the same origin AS?
Yes, and it is commonly done. I was under the impression anycast services with homogeneous origin AS was far more common than the heterogeneous. Almost all the instances I know of use homogeneous origin AS. I'd be interested in statistics either way.
192.88.99.0/24, 2002::/16, and 2001::/32 are some notable examples of heterogeneous origin AS.
I know examples of both, although I will admit I did not know any v6 ones. :) However, I'm just interested in global stats. -- TTFN, patrick
Then there is basically no inter-As anycast besides the anycast prefix for DNS root, since I only noticed like 8 prefixes that are announced by more than 3 ASes..
...but inter-domain anycast is often achieved by using a single origin AS, which is then transited through the 'provider' autonomous systems. In which case, you may be looking for the wrong thing. Rob
Rob Evans wrote:
Then there is basically no inter-As anycast besides the anycast prefix for DNS root, since I only noticed like 8 prefixes that are announced by more than 3 ASes..
...but inter-domain anycast is often achieved by using a single origin AS, which is then transited through the 'provider' autonomous systems.
Hi Rob, Do you mean multihoming here? Zhenkai
In which case, you may be looking for the wrong thing.
Rob
On Tue, Apr 21, 2009 at 11:53:02PM -0700, Zhenkai Zhu wrote:
Hello NANOG,
I noticed that more than 3K prefixes are with 2 Origin ASes. Are they the simplest cases of anycast? Or they are mainly due to misconfiguration?
--- --Zhenkai
i honestly don't remember the requirement for single-origin AS in a prefix announcement. Not sure why anyone would think that multiple origin announcements are a "misconfiguration". --bill
participants (12)
-
bmanning＠vacation.karoshi.com -
Fouant, Stefan -
Jack Bates -
Jeroen Massar -
Joe Provo -
Kevin Loch -
kris foster -
Nathan Ward -
Patrick W. Gilmore -
Rob Evans -
Shin SHIRAHATA -
Zhenkai Zhu