Subject: Top 50 unstable DVMRP routes

From: Bill Fenner <[email-masked]>
Date: Mon, 9 Mar 1998 07:57:22 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
- ------- ----- ---------- --------- ------------------- ---- --------------
      3	   30   11(36%)    18(60%) 18.26.64/24         41     14
   1347	  457  116(25%)   369(80%) 128.162.154.5/32    29     17
    786	  519  245(47%)   274(52%) 128.240.1.96/27     40     14
    668	   60   32(53%)    27(45%) 129.29.64/24        13     24
    559	  137   19(13%)   120(87%) 129.132.66.128/26   49     11
   1275	 1045  524(50%)   601(57%) 134.34.89.121/32    33     17
   1717	  661  480(72%)   182(27%) 147.210/16          7      30
   3314	    3    0(0%)      3(100%)148.6.0/21          4     118
   6744	  147   60(40%)    91(61%) 150.140.112.17/32   42     13
   1739	    2    0(0%)      2(100%)153.1/16            47     11
     -1	  735  461(62%)   255(34%) 192.35.227/24       5     102
   3339	    1    1(100%)    1(100%)192.116.143/24      46     12
   2648	   48   45(93%)     3(6%)  192.149.148/24      27     17
      0	  100   65(65%)    49(49%) 192.168.0/24        2     119
   3128	   23    2(8%)     21(91%) 192.172.224/24      14     24
   1741	  386   87(22%)   299(77%) 193.166.192/19      19     20
   1955	  304   44(14%)   274(90%) 193.225.176/23      43     13
    209	   55   23(41%)    32(58%) 198.11.20/24        35     16
      1	  512  353(68%)   189(36%) 198.49.45/24        12     25
   1312	    3    0(0%)      3(100%)198.82.167/24       37     15
    237	  103   44(42%)    59(57%) 198.109.132/24      36     16
    292	   63   45(71%)     4(6%)  198.128.16/24       3     119
   2381	   18    5(27%)    13(72%) 198.150.55/24       17     23
    800	    9    8(88%)     1(11%) 198.165.161/24      34     16
   8111	   14    7(50%)     7(50%) 198.166.1/24        31     17
    600	   68   50(73%)     9(13%) 199.18/16           21     19
   2637	   41   12(29%)    29(70%) 199.77.192/24       39     15
   3421	    4    3(75%)     1(25%) 199.177.0/24        15     24
   1680	    8    8(100%)    6(75%) 199.203/16          45     12
   4004	   23   21(91%)    12(52%) 199.203.252/24      44     12
    549	  103   99(96%)     4(3%)  199.212.24/24       38     15
   4761	    1    0(0%)      1(100%)202.155.8.64/26     22     19
   4788	  116  116(100%)  114(98%) 202.188.0/24        10     28
    145	  100   15(15%)    85(85%) 204.147.128/24      1     119
   3915	   42   38(90%)     4(9%)  204.182.44/24       8      29
   3909	   35   32(91%)     3(8%)  204.228.69/24       25     17
    210	   19   10(52%)     9(47%) 205.124.247/24      48     11
   1239	  212  188(88%)    24(11%) 205.166.205/24      9      28
    577	   17    9(52%)     8(47%) 205.189.33/24       28     17
   2493	  158  156(98%)     2(1%)  206.75.91.64/26     20     19
   3967	  689   28(4%)    662(96%) 206.79.0/24         26     17
   6296	    2    0(0%)      2(100%)206.101.72.0/28     50     10
   5754	   11    2(18%)     9(81%) 206.127.228/22      6      74
   3804	   32   30(93%)     2(6%)  206.172.49/24       32     17
     27	   12   11(91%)     1(8%)  206.196.190/24      30     17
   1225	   49   31(63%)    18(36%) 207.57.116/23       11     25
   7260	    2    1(50%)     1(50%) 207.170.6/24        16     23
   5646	   21   20(95%)     1(4%)  207.227.0/24        24     18
   3561	  381  295(77%)    84(22%) 208.151.215/24      23     18
   6541	    9    8(88%)     1(11%) 209.84.64/21        18     22

  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.

---

From: [email-masked] (Bernard TUY)
Date: Mon, 9 Mar 1998 18:58:49 +0100 (MET)

|   Date: Mon, 9 Mar 1998 07:57:22 PST
|   From: Bill Fenner <[email-masked]>
|   
|      1717	  661  480(72%)   182(27%) 147.210/16          7      30

====BT: this one should be fixed for we just move this dvmrp tunnel
	to a pim/gre one on a -at least I hope- more stable and less
	loaded mrouter.
	
  Thanx for having this results on a regular basis, it surely helps
  people to take into account such problems.
  
  Cheers,
  
  +bernard Tuy.