Top 50 unstable DVMRP routes

[Bill Fenner <]

Dear MBone and MBone-EU-OP mailing lists,

  Enclosed is the list of this week's worst DVMRP flappers.
Please see the end of this message for more information.

     AS #srcs  #down(%)  #flapping Route               Rank avg.flaps/hour
------- ----- ---------- --------- ------------------- ---- --------------
   7018	   18   15(83%)     4(22%) 12.3.167.0/25       30     36
    239	    9    5(55%)     4(44%) 128.100.98/23       38     30
    225	   15    6(40%)    12(80%) 128.143.8/24        43     24
   1347	  475  152(32%)   410(86%) 128.162.206/24      16     53
    786	  603  601(99%)   392(65%) 128.240.250/24      36     30
   2841	  327  327(100%)  327(100%)129.16.1.192/26     45     24
    668	   63   36(57%)    33(52%) 129.29.125/24       18     51
    561	    7    6(85%)     2(28%) 129.213.96/22       48     23
   5378	   18   18(100%)   18(100%)140.204.12.200/29   42     25
   1275	 1177  634(53%)   835(70%) 141.39/16           21     47
   3314	    4    4(100%)    4(100%)148.6.0/21          4     115
   1323	   33   33(100%)   28(84%) 149.112.12/24       31     36
   2506	   18   12(66%)    14(77%) 150.32/16           9      61
   2828	  135  112(82%)    87(64%) 152.67.3.0/30       34     31
   1739	    2    2(100%)    2(100%)153.1/16            33     33
   2110	    2    2(100%)    2(100%)160.6/16            39     29
   1849	  106  105(99%)   101(95%) 161.71.20/24        28     40
   2511	    4    2(50%)     3(75%) 163.138/16          23     47
     90	    2    1(50%)     2(100%)192.18.128/20       24     47
      0	  117   70(59%)    75(64%) 192.168.0/24        6     103
   3128	   23    2(8%)     21(91%) 192.172.224/24      25     45
   1955	  319  104(32%)   318(99%) 193.6.206.96/30     50     23
    766	  634  484(76%)   462(72%) 193.146.128/24      40     29
   1741	  408  408(100%)  325(79%) 193.166.192/19      14     57
   1270	   96   96(100%)   92(95%) 194.15.230/24       49     23
      1	  555  366(65%)   261(47%) 198.49.45/24        19     50
    292	   64   43(67%)    22(34%) 198.128.16/24       2     117
   2381	   20    7(35%)    15(75%) 198.150.84/24       22     47
   3421	    4    3(75%)     1(25%) 199.177.0/24        29     39
   3493	   98   84(85%)    15(15%) 199.202.116/24      13     58
   3804	   32   31(96%)     2(6%)  199.243.250/24      47     23
     -1	  932  672(72%)   550(59%) 202.8.94.0/30       8      71
   4761	    1    1(100%)    1(100%)202.155.8.64/26     41     27
   1237	   63   63(100%)   49(77%) 203.247.194/24      37     30
   3909	   35   33(94%)     3(8%)  204.131.62/24       44     24
    145	  101   83(82%)    86(85%) 204.147.128/24      3     117
   4137	    2    2(100%)    1(50%) 204.177.115.108/30  46     24
   3915	  427   31(7%)    407(95%) 204.182.44/24       11     58
   1239	  216  193(89%)    31(14%) 205.166.205/24      10     59
   3582	    2    0(0%)      2(100%)205.167.76/23       20     50
   6296	    2    0(0%)      2(100%)206.101.72.0/28     32     34
   5754	   11    2(18%)    10(90%) 206.127.228/24      5     107
   1225	   49   31(63%)    18(36%) 207.57.118/24       15     54
   6461	  158  148(93%)    17(10%) 207.126.96/24       1     118
   7260	    2    1(50%)     1(50%) 207.170.6/24        17     52
   3561	  396  308(77%)   101(25%) 208.151.215/24      7      89
    701	  407  370(90%)    71(17%) 208.198.164/24      12     58
   3967	  698   33(4%)    678(97%) 209.1.220.54/32     26     44
   5650	   38   38(100%)   14(36%) 209.63.83/24        35     31
   6541	    9    8(88%)     1(11%) 209.84.64/21        27     44


  UCLA and PARC are engaged in MBone monitoring and
measurement.  One of the major problems with the current DVMRP
MBone is route instability.  Most of the instability appears to
be caused by pathologies as opposed to real link or router
instability.  DVMRP does not handle instability well, so it's to
everyone's benefit to eliminate these pathologies.  This
periodic message is meant to point out the routes that appear
unstable in the hopes that the cause of the instability will be
corrected.

  More information on the data collection is available from

	http://ganef.cs.ucla.edu/~masseyd/Route/

  More information on the known bugs which cause instability
is available from

	http://ganef.cs.ucla.edu/~masseyd/Route/bugs.html

  We are still experimenting with the best format in which to
present this information.  We're currently grouping routes
by unicast AS number, and only reporting the worst offender
in a given AS.  Other unstable routes in the same AS can be
found by referring to the "AS Number Search" from the search
menu of the above web page, or by looking at this week's or
this month's current data on the web page.

  The fields in the following table are:
AS:
	The AS number associated with the source in the unicast
	routing table.  This may be the route's source, or may be
	the route's source's unicast provider, who may or may not
	be their multicast provider.
#sources:
	The number of sources in the DVMRP routing table associated
	with this AS.
#down:
	The number of above sources whose DVMRP routes are currently
	considered down.
#flapping:
	The number of above sources whose DVMRP routes are experiencing
	routing instability during this period.
Route:
	The most unstable route in the AS over the measurement period.
Rank:
	The rank (by flaps/hour) of this route in the top AS's.
flaps/hour:
	The average flaps-per-hour of the most unstable route.
	A stable route never flaps; if a link goes down and
	comes back up routes related to it might flap once or
	twice.  A route which flaps, on average, more than once
	per hour over a week's time, is clearly either behind a
	link that goes up and down about once an hour (which
	deserves to be investigated) or is experiencing a
	pathology like those listed on the above-referenced bugs
	page (which deserves to be investigated).

  The table lists the 50 worst AS's, sorted by the IP address of the
most unstable route in the AS, with an additional rank by most unstable
route in the AS.  This data is from a single point of view at
UCLA; the data is of course colored by its collection point.  In
particular, network problems close to the collection point can
raise the perceived instability for a large number of sources.
However, we believe that averaging over the week lessens these
effects greatly, so although there may be occasional blips, in
general if you're in this table, you should try to find out
why.