Subject: Top 50 unstable DVMRP routes

From: Bill Fenner <[email-masked]>
Date: Mon, 2 Feb 1998 08:22:01 PST

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	   21   16(76%)     5(23%) 12/8                21     29
     16	   28    1(3%)     27(96%) 128.3/16            17     34
    226	   36   19(52%)    18(50%) 128.125.253/24      24     26
   1347	  421   71(16%)   233(55%) 128.162.154.50/32   16     35
    786	  503  288(57%)   223(44%) 128.240.64/24       37     21
    760	    5    5(100%)    1(20%) 131.130/16          49     19
   7569	   25   25(100%)    4(16%) 131.170.1/24        25     23
     52	   42   31(73%)    11(26%) 131.179.113/24      42     21
   2150	   34   20(58%)    17(50%) 132.241.60.64/28    8      41
    685	   52   24(46%)    29(55%) 137.229.60/24       12     38
   7570	   14   14(100%)    3(21%) 138.25.10/23        47     20
   7574	    3    3(100%)    2(66%) 138.80.54/24        38     21
   1251	   64   56(87%)     9(14%) 143.108.14/24       50     19
     -1	  687  428(62%)   362(52%) 146.190/16          13     37
   2506	   11    4(36%)     8(72%) 150.32/16           6      47
   6744	  119   49(41%)    82(68%) 150.140.31.248/30   11     38
    766	  535  424(79%)   119(22%) 156.35.95.0/25      14     35
   2042	    5    5(100%)    3(60%) 161.142/16          4      49
   1717	 2657 2650(99%)  2613(98%) 192.54.172.0/25     5      48
      0	   88   57(64%)    51(57%) 192.168.0/23        2     119
   3128	   23    5(21%)    21(91%) 192.172.224/24      45     20
   1275	  873  499(57%)   646(73%) 193.174.34/24       18     33
   3301	   46   44(95%)     2(4%)  194.237.226.0/26    31     22
   3352	    7    4(57%)     3(42%) 195.55.11/24        19     31
    209	   54   19(35%)    35(64%) 198.11.22/24        46     20
    600	   65   44(67%)    23(35%) 198.30.5/24         40     21
   1312	    3    0(0%)      3(100%)198.82.167/24       35     22
    237	  101   41(40%)    61(60%) 198.109.132/24      28     23
   8111	   14    9(64%)     6(42%) 198.166.1/24        33     22
   3899	    1    1(100%)    1(100%)198.189.66/24       3      70
   2637	   40   11(27%)    33(82%) 199.77.192/24       44     20
    549	   95   89(93%)     7(7%)  199.212.24/24       34     22
   3804	   32   29(90%)     3(9%)  199.243.250/24      32     22
   4774	    1    1(100%)    1(100%)202.6.254/24        10     38
    145	   99   14(14%)    85(85%) 204.147.129.84/30   22     28
   3909	   35   32(91%)     3(8%)  204.228.69/24       29     22
   6197	    5    2(40%)     3(60%) 205.152.6.226/32    43     20
    577	   16    8(50%)     8(50%) 205.189.33.252/30   27     23
   2381	   17   16(94%)    13(76%) 205.213.126/24      26     23
   1225	   37   22(59%)    16(43%) 206.68.96/24        41     21
   2493	  157  156(99%)     1(0%)  206.75.91/24        30     22
   6296	    2    0(0%)      2(100%)206.101.72.0/28     23     27
   5754	   11    2(18%)     9(81%) 206.127.228/24      20     30
   3493	   92   80(86%)    13(14%) 206.167.88/24       36     21
     27	   12   11(91%)     1(8%)  206.196.190/24      39     21
   6402	   37   37(100%)   35(94%) 207.112.228/24      1     128
   7260	    2    1(50%)     1(50%) 207.170.6/24        15     35
   3561	  376  286(76%)    83(22%) 208.151.215/24      48     19
    701	  389  333(85%)    66(16%) 208.198.164/24      7      47
   5646	   21   20(95%)    18(85%) 209.100.144/24      9      39

  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.