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Re: A study on community-triggered updates in BGP
by Jakob Heitz (jheitz) 22 Oct '20

22 Oct '20

Thomas, I confirmed your case and took a look at the code. The outbound duplicate suppression function tries to detect duplicates without actually storing or recreating the previously sent update, so it misses some cases. Your use case is a good one. We will check to see if we can detect it without compromising significantly on resource usage. Thank you for raising the issue. Regards, Jakob. -----Original Message----- Date: Tue, 20 Oct 2020 04:48:37 -0700 From: Thomas Krenc <tkrenc(a)nps.edu> Hi Jakob. The simple configuration below allows communities to be forwarded (send-community-ebgp), but are cleaned at egress (using route-policy and community-set). In the experiment, the router receives announcements with altering community attributes only, from the internal peer. After the filter is applied, the router sends duplicates to the external peer. Also, In a slightly different setup, the router sends duplicates due to changes in the next-hop only. best regards Thomas --- RP/0/0/CPU0:ios(config)#show running-config Tue Oct 20 02:56:24.230 UTC Building configuration... !! IOS XR Configuration 6.0.1 !! Last configuration change at Tue Oct 20 02:56:02 2020 by cisco ! interface MgmtEth0/0/CPU0/0 ?shutdown ! interface GigabitEthernet0/0/0/0 ?ipv4 address 10.12.0.2 255.255.255.252 ! interface GigabitEthernet0/0/0/1 ?ipv4 address 10.20.0.1 255.255.255.252 ! community-set all ? *:* end-set ! route-policy nofilter ? pass end-policy ! route-policy egressfilter ? delete community in all ? pass end-policy ! router bgp 65002 ?bgp router-id 10.12.0.2 ?address-family ipv4 unicast ! ?neighbor 10.12.0.1 ? remote-as 65001 ? address-family ipv4 unicast ?? send-community-ebgp ?? route-policy egressfilter out ! ?neighbor 10.20.0.2 ? remote-as 65002 ? address-family ipv4 unicast ! end On 10/17/20 3:59 PM, Jakob Heitz (jheitz) via NANOG wrote: > IOS-XR has duplicate update suppression logic for EBGP sessions, > not for IBGP sessions. > > If you are using EBGP and seeing a fault in the duplicate update > suppression logic in IOS-XR, please let me know configs and details > of the experiment. > > Regards, > Jakob. > > -----Original Message----- > Date: Thu, 15 Oct 2020 18:35:58 -0700 > From: Thomas Krenc <tkrenc(a)nps.edu> > > Dear NANOG, > > As a team of researchers from NPS and TU Berlin, we are investigating > the impact of BGP community attributes on the update behavior between ASes. > > We find that when a route is associated with multiple distinct community > attributes it does not only lead to multiple announcement at the tagging > AS, but also at neighboring ASes, if communities are not filtered > properly. This behavior is wide-spread. > > In order to better understand our observations, we have performed a > series of laboratory experiments using Cisco IOS, Junos OS, as well as > the BIRD daemon. > > We find that - by default - all tested routers generate announcements > with changing community attributes, even when other attributes do not > change. In addition, when communities are filtered at egress, Cisco und > BIRD send duplicate announcements (Juniper does not). > > Since our findings are limited to observations in public data as well as > few router implementations, we would like to share our research and > kindly ask you to have a look at: > > ??? https://www.cmand.org/communityexploration/ > > There, we provide some resources documenting our research, as well as > open questions. We greatly appreciate any feedback and insights you can > offer. Also, please don't hesitate to contact us directly: > > ??? communityexploration AT cmand DOT org > > best regards > > Thomas Krenc > Postdoctoral Researcher > Naval Postgraduate School

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Level3/CenturyLink/Lumen in Denver, CO
by Matt Riffle 21 Oct '20

21 Oct '20

Hello, If anybody has a circuit from Level3 (aka CenturyLink or, I guess, Lumen, now) in Denver, CO — particularly if you’re in the Iron Mountain facility on Brighton Blvd — and you are willing to briefly give me an iperf3 target, please contact me off-list. I’m trying to triangulate some throughput issues. Thanks, Matt

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Juniper configuration recommendations/BCP
by Forrest Christian (List Account) 21 Oct '20

21 Oct '20

<ISP hat on> After nearly 30 years of being a cisco shop, I'm working on configuring our first pair of Juniper MX204's to replace our current provider-edge cisco. I've worked through enough of the Juniper documentation/books to have a fairly good handle on how to configure these, but I wanted to check with the list to see if there are any Juniper-Specific gotchas I might run into that isn't documented well. I've done a bit of googling and am either finding stuff that is largely Cisco-specific or which is generic - all of which I'm rather familiar with based on my past history. Is there anything I should worry about which is Juniper-specific? -- - Forrest

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RFC 2468
by Rodney Joffe 21 Oct '20

21 Oct '20

It is especially fitting whenever the NANOG/ARIN joint meetings occur in the same week that we “remember IANA”. As time has gone on, fewer and fewer of us actually know who J. Postel is - that name that appears at the end of so many RFC’s we refer to every day. The same person who also guided the management of names and numbers in the “early” days of this grand experiment we’re still struggling to get “right”. Today (Friday, October 16) is 22 years since Jon Postel passed away. I won’t start to list the rest of the pioneers we’ve lost since then - its obviously getting longer and longer. But I think its worth pointing “newcomers" at Vint’s RFC2468 (https://tools.ietf.org/rfc/rfc2468.txt) as the starting point for them (you) to understand the importance of Jon’s legacy as a moral compass to help guide some of the decisions being made or ignored during this week. And obviously other weeks and decisions that follow. Jon was my mentor, colleague, business partner, and friend. And along with his other friends still on this list, I miss him a lot. It hasn’t been the same without him. /rlj

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FTTX Consulting
by ahmed.dalaali＠hrins.net 21 Oct '20

21 Oct '20

If anyone has experience in FTTX network design can reach me off-list. The suggested design is for nearly 200K subscribers. Ahmed

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IETF I-D: "Operational Implications of IPv6 Packets with Extension Headers" (Fwd: [v6ops] WGLC on draft-ietf-v6ops-ipv6-ehs-packet-drops)
by Fernando Gont 20 Oct '20

20 Oct '20

Folks, FYI. P.S.: The relevant IETF wg list is: https://www.ietf.org/mailman/listinfo/v6ops Thanks, Fernando -------- Forwarded Message -------- Subject: [v6ops] WGLC on draft-ietf-v6ops-ipv6-ehs-packet-drops Date: Mon, 19 Oct 2020 12:35:34 -0700 From: Fred Baker <fredbaker.ietf(a)gmail.com> To: IPv6 Operations <v6ops(a)ietf.org> I'm opening a two week WGLC on draft-ietf-v6ops-ipv6-ehs-packet-drops-01.txt. This draft started in 2015, and was set aside for a while. We took it as a working group draft in July with some additional authors, it has been recently updated in response to issues raised, and the question before the house is whether it is ready for archival state - to become an RFC. There are a number of questions: - do we agree with the language? (there are probably nits to be cleaned up) - do we agree with the concepts as stated? - do we agree with the direction the draft takes us? I think the draft could use a thorough review, and having said that, am asking for volunteers. You don't have to tell me, per se; do the review and post it to the mailing list. Two weeks gets us to November 2. _______________________________________________ v6ops mailing list v6ops(a)ietf.org https://www.ietf.org/mailman/listinfo/v6ops

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Cogent Layer 2
by Mike Hammett 20 Oct '20

20 Oct '20

Are any legitimate beefs with Cogent limited to their IP policies, BGP session charges, and peering disputes? Meaning, would using them for layer 2 be reasonable? ----- Mike Hammett Intelligent Computing Solutions Midwest Internet Exchange The Brothers WISP

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Virginia voter registration down due to cable cut
by Sean Donelan 20 Oct '20

20 Oct '20

On the last day of Virginia voter registration, the state-wide voter registration system experienced a cable cut disrupting access to the state-wide database system. Absent clear and convincing evidence otherwise, the problems will likely be caused by the usual stupid stuff. VITA @VITAagency A fiber cut near Rt. 10 in Chester near the Commonwealth Enterprise Solutions Center (CESC) is impacting data circuits and virtual private network (VPN) connectivity for multiple Commonwealth agencies. VITA @VITAagency Technicians are on site and working to repair the cut; updates will be provided as work progresses.

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A study on community-triggered updates in BGP
by Jakob Heitz (jheitz) 20 Oct '20

20 Oct '20

IOS-XR has duplicate update suppression logic for EBGP sessions, not for IBGP sessions. If you are using EBGP and seeing a fault in the duplicate update suppression logic in IOS-XR, please let me know configs and details of the experiment. Regards, Jakob. -----Original Message----- Date: Thu, 15 Oct 2020 18:35:58 -0700 From: Thomas Krenc <tkrenc(a)nps.edu> Dear NANOG, As a team of researchers from NPS and TU Berlin, we are investigating the impact of BGP community attributes on the update behavior between ASes. We find that when a route is associated with multiple distinct community attributes it does not only lead to multiple announcement at the tagging AS, but also at neighboring ASes, if communities are not filtered properly. This behavior is wide-spread. In order to better understand our observations, we have performed a series of laboratory experiments using Cisco IOS, Junos OS, as well as the BIRD daemon. We find that - by default - all tested routers generate announcements with changing community attributes, even when other attributes do not change. In addition, when communities are filtered at egress, Cisco und BIRD send duplicate announcements (Juniper does not). Since our findings are limited to observations in public data as well as few router implementations, we would like to share our research and kindly ask you to have a look at: ??? https://www.cmand.org/communityexploration/ There, we provide some resources documenting our research, as well as open questions. We greatly appreciate any feedback and insights you can offer. Also, please don't hesitate to contact us directly: ??? communityexploration AT cmand DOT org best regards Thomas Krenc Postdoctoral Researcher Naval Postgraduate School

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Recent List Spam
by Bryan Fields 19 Oct '20

19 Oct '20

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Looks like this recent spammer has been removed from the list. They were moderated, and using the email address From: or known users. Thanks, - -- Bryan Fields 727-409-1194 - Voice http://bryanfields.net -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEaESdNosUjpjcN/JhYTmgYVLGkUAFAl+NvKMACgkQYTmgYVLG kUAcGRAAlQ/VmB99Y+by+BPQpNVFnlAHC2vtBz4fqXINHg0rONhsyc6I8RVfvSnN bxrWh5ewduqnQPQzIB14FFMCiNqSQUqro8iYh3bZ/BknQ3nPn82zUjyGD1BQBMUv Iv43O57OGc7rK/z1SS2xzMedmsSdUsRbwEHP2lSWqXvNBWnuG17lC2ITvGf796UR I1BYj/eh5bp262KBDQfTxGuX+4FECVd8aho8wWQxVwJil5R7sMuDpHFn/Ikm1Bde SevZ5JaW4NyX0RxOjGlNWFM7ic76GVxdAj4I3sCkokVkuSf9kh4rNrbU+VFwMJ/h iqR/qCKPEGeDotFj8GpCBogb8ywAzn6wUwKVB5Ax9hWyrolIsxODS939HF1ayVah 9PL6bcVo1yKu458VmV7kdsy16zHGQnMoE0giZfbqQvxyKyE6CzqJnDN7UFfNH+Nv lKxHJwpx7YC2Wr4co7tZrXUSOq2RbyV39BkPetFo8zGy5lqs6vfzDsHwIdAGYkgU 14N45NW/g9sLDxUOso7pT1EsLGpF/Cl86MVp9A8wP4A0U1kqZJbHnWXYloSS0qq5 ideKbex+keLOBuTqbZ2/+NOpi+8C+t8kGdAu+H5Hr/a/wvlD8zMpE9OP1fKbycAk e4HadiStrFj9/PH4CecT4jNc535KcOGePmA6EFOlPMEV//K8L7I= =PfBg -----END PGP SIGNATURE-----

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