Anycast routing Denver to Chicago

Questions / Help
1

I’m being routed to ord rather then den from a residential network in Denver as seen on debug.fly.dev:

Start: 2025-04-21T02:06:13-0400
                                  Loss%   Snt Drop   Last   Avg  Best StDev  Wrst
  1. AS???    192.168.0.1          0.0%    10    0    0.7   0.8   0.6   0.3   1.7
  2. AS209    hlrn-dsl-gw16.hlrn.  0.0%    10    0    3.6   3.6   3.2   0.5   4.9
  3. AS209    63-225-124-121.hlrn  0.0%    10    0    2.6   4.3   2.6   2.0   9.1
  4. AS3356   lag-15.ear2.den1.sp 90.0%    10    9    4.4   4.4   4.4   0.0   4.4
  5. AS3356   6453-3356-den.sp.lu  0.0%    10    0    4.8   4.5   3.4   0.5   4.9
  6. AS6453   if-bundle-50-3.qcor 20.0%    10    2   26.9  26.5  25.4   0.6  27.3
  7. AS6453   if-bundle-2-2.qcore  0.0%    10    0   26.2  25.8  25.0   0.5  26.5
  8. AS6453   66.110.15.43         0.0%    10    0   26.3  25.7  24.8   0.6  26.5
  9. AS40509  77.83.140.164        0.0%    10    0   26.3  25.9  24.9   0.6  26.3
3

we applied a fix for this, is it looking any better?

1 Like
4

Hey thanks for taking a look!

Unfortunately I’m seeing the same behavior for now but I can check again tonight in case the old routing is cached somewhere.

Last time I took the mtr overnight when most of the nodes were (slightly) more responsive to pings. Today they are less so, but same routing path:

Start: 2025-04-22T12:49:35-0400
HOST:                             Loss%   Snt Drop   Last   Avg  Best StDev  Wrst
  1. AS???    192.168.0.1          0.0%    30    0    0.7   0.7   0.5   0.2   1.2
  2. AS209    hlrn-dsl-gw16.hlrn.  0.0%    30    0    3.6   4.3   2.5   2.9  18.7
  3. AS209    63-225-124-121.hlrn  0.0%    30    0    3.9   4.2   2.6   1.6  11.0
  4. AS???    ???                 100.0    30   30    0.0   0.0   0.0   0.0   0.0
  5. AS3356   6453-3356-den.sp.lu  0.0%    30    0    4.8   6.0   4.4   4.5  28.5
  6. AS6453   if-bundle-50-3.qcor 53.3%    30   16   28.2  26.9  26.1   0.7  28.2
  7. AS6453   if-bundle-2-2.qcore 30.0%    30    9   27.1  26.2  24.8   0.5  27.2
  8. AS6453   66.110.15.43         0.0%    30    0   26.4  29.8  25.8  13.0  93.6
  9. AS40509  77.83.140.164        0.0%    30    0   26.1  26.5  25.1   0.4  27.3

I was unable to get a response from the 4th host at all this time but probably safe to assume it’s still the same CenturyLink node that was already being flakey during off peak.

5

okay, this time it should actually be fixed :slight_smile:

we don’t have peering to lumen/tata in denver, but we were able to find a better route through comcast.

btw: it’s fairly normal for core routers to not accept pings, or to heavily deprioritize them to use CPU to process packet routing to elsewhere instead. jsyk :​)

1 Like
6

That did it, thanks so much for the help. Everything is super snappy now!

btw: it’s fairly normal for core routers to not accept pings, or to heavily deprioritize them to use CPU to process packet routing to elsewhere instead. jsyk :​)

The more you know!

For posterity, one last mtr:

Start: 2025-04-22T16:19:55-0600
HOST:                             Loss%   Snt Drop   Last   Avg  Best  Wrst StDev
  1. AS???    192.168.0.1          0.0%    10    0    0.6   0.5   0.4   0.7   0.1
  2. AS209    207.225.112.16       0.0%    10    0    3.5   4.2   3.1  11.3   2.5
  3. AS209    63.225.124.121       0.0%    10    0    4.1   3.5   2.7   4.1   0.4
  4. AS???    ???                 100.0    10   10    0.0   0.0   0.0   0.0   0.0
  5. AS3356   4.69.219.74         30.0%    10    3    3.5   7.6   3.5  18.0   5.1
  6. AS3356   4.68.74.14           0.0%    10    0    4.9   4.6   4.2   5.0   0.3
  7. AS7922   96.110.33.126       60.0%    10    6    5.7   6.0   5.7   6.3   0.3
  8. AS7922   96.87.9.190          0.0%    10    0    4.8   9.1   3.8  47.5  13.5
  9. AS40509  77.83.140.164        0.0%    10    0    4.0   4.0   3.1   4.4   0.4
7

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