Re: [Idr] Choice of Large vs. Extended Community for Route Leaks Solution

["Sriram, Kotikalapudi (Fed)" <[e-mail]>]

Jakob,

Thanks. I was expecting this question. We will work on a recursive path analysis to answer it. Brian's suggestion also will be considered. The data crunching may take a week or so.

My hunch was that when the AS path length is 5 or 6 or more, the ASes at the far end (most recently added) are not likely the savvy ones to be doing EC/LC but more likely the earlier ASes added the EC/LC. We'll see what the more detailed data analysis reveals.   

Sriram 

________________________________________
From: Jakob Heitz (jheitz) <[e-mail]>
Sent: Friday, April 2, 2021 2:38 AM
To: Sriram, Kotikalapudi (Fed)
Cc: Jeffrey Haas; Susan Hares; [e-mail]; [e-mail]; [e-mail]; [e-mail]; Brian Dickson
Subject: Re: Choice of Large vs. Extended Community for Route Leaks Solution

When the collector sees a route with AS-PATH length 5 with a community on it, that does not imply that the community traveled through 5 AS hops. The community could have been added at any of the ASes in the path. Where does the data show that any communities transited any AS boundaries?

Regards,
Jakob.


> On Apr 1, 2021, at 2:06 PM, Sriram, Kotikalapudi (Fed) <[e-mail]> wrote:
>
> There may be a knob that AS operators have for permitting transitivity, but we need to look at measurements to understand whether or not operators actually allow transitivity to EC and LC.
>
> NIST BGP measurements (thanks to my colleague Lilia Hannachi) were shared on the GROW list in May 2020:
> https://gcc02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmailarchive.ietf.org%2Farch%2Fmsg%2Fgrow%2FJPD1-hhSvVXIZbUlNQ_1hmzD6IA%2F&amp;data=04%7C01%7Ckotikalapudi.sriram%40nist.gov%7C7e0ddfc991ff4aa54f9308d8f5a1e8e7%7C2ab5d82fd8fa4797a93e054655c61dec%7C1%7C0%7C637529423059320205%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=WPgxMhjSfAx%2FueDd487sVRqVWCAYY%2FMIF51gzbf%2Bm7Q%3D&amp;reserved=0
>
> A portion is copied below. The AS path length (# unique ASes) distributions for BGP updates with Communities (Regular, Large, and Extended) are shown here. It is evident that both LC and EC propagate multiple AS hops. Mass stripping of LC or EC at the first hop is not evident.  The peak happens at AS path length 4 or 5 and that is good. That is the behavior that is helpful for route leak solution. The solution can still function even if some ASes strip. We can do some more detailed studies if needed.
>
> *********************************************************************
> RIPE-RIS: Community ANALYSIS (Collector : rrc03 From 2020-04-30 00:00 To 2020-04-30 00:55)
> *********************************************************************
> # Updates = 1075583 (Total)
> # (Regular) COMMUNITY = 859239 (79.89%)
> AS path length distribution =    1: 170 (0.02%)    2: 44803 (5.21%)    3: 141072 (16.42%)    4: 276271 (32.15%)    5: 238325 (27.74%)    6: 114158 (13.29%)    7: 31365 (3.65%)    8: 9018 (1.05%)    9: 2690 (0.31%)    10: 811 (0.09%)    11: 358 (0.04%)    12: 169 (0.02%)    13: 22 (0%)    14: 7 (0%)
>
> # LARGE_COMMUNITY = 152818 (14.21%)
> AS path length distribution =    2: 5655 (3.7%)    3: 17205 (11.26%)    4: 54372 (35.58%)    5: 45492 (29.77%)    6: 22065 (14.44%)    7: 6422 (4.2%)    8: 1068 (0.7%)    9: 397 (0.26%)    10: 71 (0.05%)    11: 35 (0.02%)    12: 26 (0.02%)    13: 6 (0%)    14: 4 (0%)
>
> # EXTENDED COMMUNITIES = 44606 (4.15%)
> AS path length distribution =    2: 2269 (5.09%)    3: 7435 (16.67%)    4: 17657 (39.58%)    5: 11600 (26.01%)    6: 3967 (8.89%)    7: 1221 (2.74%)    8: 371 (0.83%)    9: 57 (0.13%)    10: 19 (0.04%)    11: 8 (0.02%)    12: 1 (0%)    13: 1 (0%)
> *********************************************************************
>
> Sriram