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RE: Pitfalls of annoucing /24s
by McBurnett, Jim 16 Oct '03

16 Oct '03

->-----Original Message----- ->From: Phil Rosenthal [mailto:pr@isprime.com] ->As long as it's provider assigned, and your provider announces the ->supernet that the /24 is from, it will still work. If you ->announce PI ->space out of the old class A space in /24's, many networks ->wont be able ->to reach you. I am not sure I agree with this. We are annoucing a /24 from the 66 /8 block and I have only found 2 ISP's (according the the netlantis project) that can't reach me. We are multihomed. I suspect that may be due to aggregation. But even with our backup online, I still saw the routes propogate via Netlantis.. Or am I out in left field going nuts? Later, Jim

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Re: possible ORG problems, maybe?
by Brandon Butterworth 16 Oct '03

16 Oct '03

> it would appear that given the large scale > ddos attacks against networks, and dns in particular over the last year, > an anycast implementation is the *only* way that dns has a chance of > surviving. It might help but isn't a cure all. If they can query it they can DoS it and given the splay of zombies vs your servers there should be enough to kill them all dns serving P2P style (I'm not suggesting someone should do it) would even up the odds, with enough penetration you could get 1:1 so they all attack themselves. > In terms of UltraDNS, we try to make it easier by having the following > two records on every server: > dig @[UltraDNS Anycast name or ip address] whoareyou.ultradns.net A > and > dig @[UltraDNS Anycast name or ip address] whoami.ultradns.net A more useful would be to make a query that returned the answers from all your servers (obfuscated if necessary) so we can see which is different & have data to report the problem I presume you have such a tool internally for regression testing brandon

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It's been 5 years...
by Rodney Joffe 16 Oct '03

16 Oct '03

| Jon Postel | August 6, 1943 - October 16, 1998 ftp://ftp.isi.edu/in-notes/rfc2468.txt Stop all the clocks, cut off the telephone, Prevent the dog from barking with a juicy bone, Silence the pianos and with muffled drum Bring out the coffin, let the mourners come. Let aeroplanes circle moaning overhead Scribbling on the sky the message He Is Dead, Put crepe bows round the white necks of the public doves, Let the traffic policemen wear black cotton gloves. He was my North, my South, my East and West, My working week and my sunday rest, My noon, my midnight, my talk, my song; I thought that love would last for ever: I was wrong. The stars are not wanted now: put out every one; Pack up the moon and dismantle the sun; Pour away the ocean and sweep up the wood. For nothing now can ever come to any good. W. H. Auden /rlj

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RE: Pitfalls of annoucing /24s
by H. Michael Smith, Jr. 16 Oct '03

16 Oct '03

This is a part of the problem. I realize that large ISPs are probably against micro-assignments so that they can continue to use address space to treat customers as indentured servants. I guess they can skip Chicago and just filter out any micro-assignments that ARIN may one day issue. My biggest gripe on this topic is about ISPs that assign /24's to multi-homed customers, but filter out /24's received from peers. Verio (the example of the day) accepts /24's (that they likely assigned) from customers but filters these out from others. Are they expecting their peers not to filter these /24's or do they really care? I suppose if their peers adopt filtering policies such as theirs, they can just tell their customers "We accept your /24, but the other guy is filtering it out" Michael -----Original Message----- From: Andrew Dul [mailto:andrew.dul@quark.net] Sent: Wednesday, October 15, 2003 11:35 PM To: Forrest; michael(a)awtechnologies.com Cc: nanog(a)merit.edu Subject: RE: Pitfalls of annoucing /24s Forrest, Even if ARIN passes this policy that will not make any provider change their filtering policy. It is true that many providers do use the ARIN allocation sizes to create their filtering rules but the two are not inherently linked. Any ASN can choose the filter on what ever rule set they choose. Andrew At 04:38 PM 10/15/2003 -0500, Forrest wrote: > > >This is just one of the many reasons why we need ARIN proposal 2002-3 to >be approved. So that small networks that wish to multihome don't have >issues with networks filtering out their /24 along with all the other >garbage /24's that are announced. > >http://www.arin.net/policy/2002_3.html > >If you support 2002-3 I urge you to get on the ARIN Public Policy >Mailing List (PPML) and voice your opinion. > >http://www.arin.net/mailing_lists/index.html > >Forrest > > >-----Original Message----- >From: H. Michael Smith, Jr. [SMTP:michael@awtechnologies.com] >Sent: Wednesday, October 15, 2003 4:24 PM >To: 'Phil Rosenthal'; 'John Palmer' >Cc: nanog(a)merit.edu >Subject: RE: Pitfalls of annoucing /24s > > > >What about the /24's that many ISPs (especially tier 2-3) are assigning >to multi-homed customers? What about an IX or "critical infrastructure >providers" that may be issued a /24 from ARIN (Policy 2001-3)? > >Although it may be rare that a large aggregate would become unreachable >to a "large" network, doesn't the possibility exist that a customer with >a /24 would become unreachable (to some) due to the aggregate dropping >out even though the /24 should still be reachable? That scenario may >not be very likely, but the question of assymetric routing and one's >ability to balance traffic become issues. Assigning a lower preference >to /24's would be a lot friendlier than just throwing them away. > >If I am way off base, I fully expect to be corrected (with volume). My >flame retardant suit is in place. > >Michael > >-----Original Message----- >From: owner-nanog(a)merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of >Phil Rosenthal >Sent: Wednesday, October 15, 2003 4:47 PM >To: John Palmer >Cc: nanog(a)merit.edu >Subject: Re: Pitfalls of annoucing /24s > > >http://info.us.bb.verio.net/routing.html#PeerFilter > >That's how Verio does it, and I assume, that's how most people who >filter by length do it as well. > >--Phil >On Oct 15, 2003, at 4:40 PM, John Palmer wrote: > >> >> Good question. >> >> You know there are thousands of legacy /24's out there that were >> allocated by >> IANA as /24's How can you aggregate them up if all you have is the >/24? >> >> To those who filter out /24's - how is this done - just by the netmask > >> size? >> >> ----- Original Message ----- >> From: "Jean-Christophe Smith" <jsmith(a)vitalstream.com> >> To: <nanog(a)merit.edu> >> Sent: Wednesday, October 15, 2003 15:34 >> Subject: Pitfalls of annoucing /24s >> >> >>> >>> >>> In current practice would there be serious jeopardy of portions of >the >>> internet not being able to reach this address space due to bgp >>> filters or >>> other restrictions? What is the smallest acceptable block of IPs that > >>> can be >>> announced without adverse or unpredictable results? Verio would most >>> likely >>> be picking up these routes from us. I don't want to cause a religious >>> debate, but I am interested in what the industry consensus is. >>> >>> I'm just doing some research, any comments would be appreciated. >>> >>> Thanks, >>> Jean-Christophe Smith >>> >>> >> >> >--Phil Rosenthal >ISPrime, Inc. > > > > > > >

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RE: Pitfalls of annoucing /24s
by H. Michael Smith, Jr. 15 Oct '03

15 Oct '03

What about the /24's that many ISPs (especially tier 2-3) are assigning to multi-homed customers? What about an IX or "critical infrastructure providers" that may be issued a /24 from ARIN (Policy 2001-3)? Although it may be rare that a large aggregate would become unreachable to a "large" network, doesn't the possibility exist that a customer with a /24 would become unreachable (to some) due to the aggregate dropping out even though the /24 should still be reachable? That scenario may not be very likely, but the question of assymetric routing and one's ability to balance traffic become issues. Assigning a lower preference to /24's would be a lot friendlier than just throwing them away. If I am way off base, I fully expect to be corrected (with volume). My flame retardant suit is in place. Michael -----Original Message----- From: owner-nanog(a)merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Phil Rosenthal Sent: Wednesday, October 15, 2003 4:47 PM To: John Palmer Cc: nanog(a)merit.edu Subject: Re: Pitfalls of annoucing /24s http://info.us.bb.verio.net/routing.html#PeerFilter That's how Verio does it, and I assume, that's how most people who filter by length do it as well. --Phil On Oct 15, 2003, at 4:40 PM, John Palmer wrote: > > Good question. > > You know there are thousands of legacy /24's out there that were > allocated by > IANA as /24's How can you aggregate them up if all you have is the /24? > > To those who filter out /24's - how is this done - just by the netmask > size? > > ----- Original Message ----- > From: "Jean-Christophe Smith" <jsmith(a)vitalstream.com> > To: <nanog(a)merit.edu> > Sent: Wednesday, October 15, 2003 15:34 > Subject: Pitfalls of annoucing /24s > > >> >> >> In current practice would there be serious jeopardy of portions of the >> internet not being able to reach this address space due to bgp >> filters or >> other restrictions? What is the smallest acceptable block of IPs that >> can be >> announced without adverse or unpredictable results? Verio would most >> likely >> be picking up these routes from us. I don't want to cause a religious >> debate, but I am interested in what the industry consensus is. >> >> I'm just doing some research, any comments would be appreciated. >> >> Thanks, >> Jean-Christophe Smith >> >> > > --Phil Rosenthal ISPrime, Inc.

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RE: Pitfalls of annoucing /24s
by H. Michael Smith, Jr. 15 Oct '03

15 Oct '03

Even if they understand it, why should they accept it? If an ISP assigns an address block, runs BGP with the customer, promotes multi-homing, shouldn't they make a reasonable effort to make it work? Unless I am missing something, I am having a big problem with an ISP assigning a /24 to a multi-homed customer and not accepting /24 routes. -----Original Message----- From: owner-nanog(a)merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of William Caban Sent: Wednesday, October 15, 2003 5:44 PM To: Jean-Christophe Smith Cc: NANOG Subject: RE: Pitfalls of annoucing /24s I will say most probably yes. I have seen this "problem"(?) on many small business customers. The hard part is trying to explain that to them. -William On Wed, 2003-10-15 at 17:16, Jean-Christophe Smith wrote: > I noticed the verio filter policy, in relation to inbound: > - In the traditional Class A space (i.e., 0/1), we accept /22 and shorter. > > If I want to announce a /24 in the 64.x.x.x space(traditional Class A space) > am I'm going to have a problem with other networks that have peer filters > similar to Verios? > > Thanks, > Jean-Christophe Smith -- William Caban <william(a)hpcf.upr.edu>

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RE: Pitfalls of annoucing /24s
by H. Michael Smith, Jr. 15 Oct '03

15 Oct '03

Understood. But... networks filtering out the /24 announcement will always prefer the aggregate learned from the owner/issuer of the space. They'll be completely unaware that another route exists to the (/24) network. If the customers link to the provider that assigned the space goes down, those filtering /24's will still send the traffic to the 'owner' of the space (right?). What is the issuer of the /24 is filtering incoming /24 advertisements (Verio)? Will they learn the route to the other ISP or blackhole traffic destined for their own customer? I keep hoping that I am missing something here. If not, I sure hope more folks don't adopt Verio's filtering techniques. (I know that a VERY low AS # issues /24's out of a /8) -----Original Message----- From: Phil Rosenthal [mailto:pr@isprime.com] Sent: Wednesday, October 15, 2003 5:42 PM To: H. Michael Smith, Jr. Cc: nanog(a)merit.edu; 'John Palmer' Subject: Re: Pitfalls of annoucing /24s On Oct 15, 2003, at 5:24 PM, H. Michael Smith, Jr. wrote: > > > What about the /24's that many ISPs (especially tier 2-3) are assigning > to multi-homed customers? What about an IX or "critical infrastructure > providers" that may be issued a /24 from ARIN (Policy 2001-3)? > As long as it's provider assigned, and your provider announces the supernet that the /24 is from, it will still work. If you announce PI space out of the old class A space in /24's, many networks wont be able to reach you.

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Pitfalls of annoucing /24s
by Jean-Christophe Smith 15 Oct '03

15 Oct '03

In current practice would there be serious jeopardy of portions of the internet not being able to reach this address space due to bgp filters or other restrictions? What is the smallest acceptable block of IPs that can be announced without adverse or unpredictable results? Verio would most likely be picking up these routes from us. I don't want to cause a religious debate, but I am interested in what the industry consensus is. I'm just doing some research, any comments would be appreciated. Thanks, Jean-Christophe Smith

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Re: Pitfalls of annoucing /24s
by Andrew - Supernews 15 Oct '03

15 Oct '03

>>>>> "Phil" == Phil Rosenthal <pr(a)isprime.com> writes: Phil> http://info.us.bb.verio.net/routing.html#PeerFilter Phil> That's how Verio does it, and I assume, that's how most people Phil> who filter by length do it as well. We currently see 28804 /24 prefixes from our transits and peers which are not more-specifics of another prefix that we see. (We see 127981 prefixes in total at the moment, so that's 22.5% of our table). By comparison, we see 41066 /24 prefixes which are more-specifics for another prefix, which is 32.1% of the table. In total, /24s account for 54.6% of the routes we see. Of those 28804 isolated /24 routes, 946 are in "class A" space (0-127), 604 are in "class B" space (128-191), and the remaining 27254 are in "class C" space (192-223). The detailed breakdown by /8 is: /8 |/24 routes | /24 routes |with aggr. | isolated ====|===========|============= 4 39 0 12 722 0 13 1 0 15 6 0 16 1 0 17 2 0 20 5 1 24 706 117 25 0 1 32 94 0 38 50 0 40 23 0 43 1 0 44 2 0 55 1 0 57 11 0 61 281 32 62 360 82 63 1897 8 64 1693 102 65 2012 2 66 1918 250 67 328 35 68 381 13 69 206 71 80 218 197 81 233 31 82 15 4 128 68 26 129 149 3 130 60 2 131 63 13 132 11 8 134 107 5 135 6 4 136 176 2 137 88 21 138 65 1 139 41 9 140 131 1 141 125 11 142 92 1 143 46 0 144 79 7 145 32 1 146 145 124 147 54 12 148 287 4 149 68 11 150 120 1 151 58 2 152 219 2 153 57 1 154 7 0 155 125 4 156 53 5 157 39 4 158 139 1 159 127 16 160 43 3 161 56 13 162 182 180 163 59 4 164 111 14 165 129 23 166 87 9 167 285 19 168 163 12 169 86 8 170 298 17 171 8 0 192 582 4767 193 744 1703 194 672 1326 195 637 639 196 123 350 198 972 2499 199 1064 1763 200 1136 1877 201 1 0 202 1810 2229 203 1426 3775 204 1471 1488 205 1004 1028 206 1630 453 207 2116 370 208 2532 31 209 2294 485 210 761 130 211 320 60 212 642 275 213 611 360 214 15 0 215 22 0 216 2048 1203 217 629 424 218 95 16 219 33 0 220 113 2 221 13 0 222 0 1 -- Andrew, Supernews

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RE: Pitfalls of annoucing /24s
by Jean-Christophe Smith 15 Oct '03

15 Oct '03

I noticed the verio filter policy, in relation to inbound: - In the traditional Class A space (i.e., 0/1), we accept /22 and shorter. If I want to announce a /24 in the 64.x.x.x space(traditional Class A space) am I'm going to have a problem with other networks that have peer filters similar to Verios? Thanks, Jean-Christophe Smith -----Original Message----- From: Phil Rosenthal [mailto:pr@isprime.com] Sent: Wednesday, October 15, 2003 1:47 PM To: John Palmer Cc: nanog(a)merit.edu Subject: Re: Pitfalls of annoucing /24s http://info.us.bb.verio.net/routing.html#PeerFilter That's how Verio does it, and I assume, that's how most people who filter by length do it as well. --Phil On Oct 15, 2003, at 4:40 PM, John Palmer wrote: > > Good question. > > You know there are thousands of legacy /24's out there that were > allocated by > IANA as /24's How can you aggregate them up if all you have is the /24? > > To those who filter out /24's - how is this done - just by the netmask > size? > > ----- Original Message ----- > From: "Jean-Christophe Smith" <jsmith(a)vitalstream.com> > To: <nanog(a)merit.edu> > Sent: Wednesday, October 15, 2003 15:34 > Subject: Pitfalls of annoucing /24s > > >> >> >> In current practice would there be serious jeopardy of portions of the >> internet not being able to reach this address space due to bgp >> filters or >> other restrictions? What is the smallest acceptable block of IPs that >> can be >> announced without adverse or unpredictable results? Verio would most >> likely >> be picking up these routes from us. I don't want to cause a religious >> debate, but I am interested in what the industry consensus is. >> >> I'm just doing some research, any comments would be appreciated. >> >> Thanks, >> Jean-Christophe Smith >> >> > > --Phil Rosenthal ISPrime, Inc.

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