Subject: Top 50 unstable DVMRP routes

From: Bill Fenner <[email-masked]>
Date: Mon, 22 Jun 1998 21:51:26 PDT

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
------- ----- ---------- --------- ------------------- ---- --------------
      0	   81   34(41%)    11(13%) 10/8                3     119
      3	  286  253(88%)    36(12%) 18.24.7.35/32       22     20
   2686	   31   31(100%)    1(3%)  32/8                34      9
    721	    5    4(80%)     1(20%) 128.47.27/24        49      2
     26	   15    7(46%)     1(6%)  128.84/16           31     12
   1347	  409  288(70%)    68(16%) 128.162.154.32/32   13     36
    786	  400  202(50%)    60(15%) 128.240.149/24      26     15
    668	   45   13(28%)     7(15%) 129.29.127/24       16     32
     83	   15   12(80%)     2(13%) 129.139.14/23       10     45
   2637	   21    0(0%)     19(90%) 130.207/16          15     33
   2836	   10    6(60%)     1(10%) 130.237/16          38      5
   2831	    1    0(0%)      1(100%)130.240/16          37      5
     87	  234   11(4%)    134(57%) 134.68.31.137/32    19     24
   1251	  198  164(82%)   184(92%) 143.106.80.128/26   23     19
    701	   60   27(45%)    18(30%) 146.225.66/24       28     13
   2150	   33   14(42%)     4(12%) 146.244/16          18     30
    766	  307  105(34%)    39(12%) 150.214.205.18/32   39      5
     52	   17    3(17%)     6(35%) 164.67/16           21     20
   2685	    7    7(100%)    5(71%) 165.87/16           35      8
   1852	    5    0(0%)      1(20%) 192.35.216/24       20     21
    194	    8    6(75%)     2(25%) 192.52.106/24       17     30
   1853	   27   15(55%)     1(3%)  193.170.243/24      33     10
   1955	  265  259(97%)     7(2%)  193.224.208/24      24     18
   5408	    6    2(33%)     1(16%) 194.177.208/24      41      5
   1275	 1111  732(65%)    51(4%)  195.37.193/24       14     36
   2852	   75   26(34%)    20(26%) 195.113.69/24       25     17
   5617	   11    0(0%)      2(18%) 195.117.3.0/25      48      2
    237	   74   62(83%)    12(16%) 198.108.60/24       7      55
    297	   59   20(33%)     1(1%)  198.123.65.136/29   45      2
   3128	   21    2(9%)      3(14%) 198.150.3/24        9      47
   2381	   21    7(33%)    13(61%) 198.150.38/24       11     45
     46	  139  135(97%)     4(2%)  198.151.130/24      40      5
   1239	   82   58(70%)    19(23%) 198.206.181/24      12     36
   3447	  154    6(3%)      3(1%)  199.44.22/24        50      2
      1	  267   89(33%)    40(14%) 199.45.0/24         8      49
    816	   17   16(94%)    11(64%) 200.9.88/24         29     13
   7340	    1    1(100%)    1(100%)200.10.108/22       36      7
   7414	   27   27(100%)   25(92%) 200.225.1/24        32     10
   1916	   56   56(100%)   52(92%) 200.239.239/24      30     12
   6505	   10   10(100%)   10(100%)200.240.0/20        46      2
   4230	   22   22(100%)   22(100%)200.255.103/24      44      2
     -1	 5481 5151(93%)    47(0%)  202.8.94.0/30       1     190
    145	   27    1(3%)      6(22%) 204.147.129.76/30   42      4
    144	    3    2(66%)     1(33%) 204.178.16/24       43      4
   2568	   49    5(10%)    44(89%) 204.216.248/24      47      2
   2828	   19   11(57%)     1(5%)  205.158/16          6     119
   6194	    2    0(0%)      2(100%)206.138.168/24      27     13
   3561	  151   71(47%)     5(3%)  208.151.215.0/30    4     119
   4277	    1    0(0%)      1(100%)208.213.150.0/26    5     119
   6461	  165  150(90%)     7(4%)  209.66.64/24        2     119

  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.

------- End of Forwarded Message