Subject: Top 50 unstable DVMRP routes

From: Bill Fenner <[email-masked]>
Date: Sun, 4 Jan 1998 23:30:23 PST

Dear MBone and MBone-EU-OP mailing lists,

  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.

     AS #srcs  #down(%)  #flapping Route               Rank avg.flaps/hour
------- ----- ---------- --------- ------------------- ---- --------------
    714	  538  522(97%)    56(10%) 17.3.248/22         22     20
     16	   27    1(3%)      1(3%)  128.3/16            8      32
    226	   35   14(40%)     9(25%) 128.125.10/24       15     28
    209	   53   19(35%)    34(64%) 128.138.193.0/26    44      3
    159	    3    0(0%)      3(100%)128.146/16          33     12
     34	    8    7(87%)     1(12%) 128.175.13.36/32    9      31
    786	  425  253(59%)    64(15%) 128.240.1.96/27     16     25
     77	    1    0(0%)      1(100%)128.244.93.3/32     11     30
    766	  479  383(79%)    98(20%) 130.206.122/24      5      45
   2637	   36    4(11%)     2(5%)  130.207.244.30/32   14     30
    600	   54   48(88%)     6(11%) 131.123.2/24        31     12
   2150	   34   19(55%)     2(5%)  132.241.60.64/28    42      3
    745	    2    1(50%)     1(50%) 134.205.93.150/32   13     30
   1717	  287  138(48%)    36(12%) 147.210/16          4      49
   6744	   40   37(92%)     3(7%)  150.140.40/24       7      37
   6640	    1    0(0%)      1(100%)150.159/16          32     12
   1739	    2    0(0%)      2(100%)153.1/16            20     21
   6412	    2    2(100%)    1(50%) 168.187/16          38      7
     -1	  352  221(62%)    42(11%) 192/8               17     24
      1	  327  211(64%)    27(8%)  192.42.110.249/32   6      38
   1755	    8    6(75%)     1(12%) 192.121.156/24      10     31
   3112	    1    0(0%)      1(100%)192.138.88/24       34     12
   3128	   22    2(9%)     20(90%) 192.160.134/24      25     16
      0	   69   41(59%)    13(18%) 192.168.0/24        3     114
   1741	  361   51(14%)   310(85%) 193.167.107/24      18     23
   1275	  797  469(58%)    84(10%) 193.174.34/24       12     30
   5617	    6    0(0%)      2(33%) 195.117.3.0/25      39      6
   2752	   35   35(100%)    1(2%)  198.80.133/24       50      3
   2381	   16    4(25%)    12(75%) 198.150.86/24       27     15
   6136	    4    4(100%)    1(25%) 199.33.245/24       45      3
   6461	  134   12(8%)    110(82%) 199.46.16/24        1     130
   3967	   14   10(71%)     2(14%) 199.46.18/24        36      8
   5786	   19   19(100%)    1(5%)  199.78.154/24       46      3
   2572	   16   16(100%)    1(6%)  199.79.155/24       49      3
   1335	    2    1(50%)     2(100%)199.190.24.8/29     43      3
   4433	   48   48(100%)    1(2%)  203.31.199/24       47      3
   2563	   23   16(69%)     3(13%) 203.252.134/24      35     12
   3602	  139  139(100%)    1(0%)  204.50.237/24       48      3
   3909	   35   32(91%)     3(8%)  204.131.62/24       30     13
    145	   98   15(15%)    77(78%) 204.147.131.76/30   28     13
    577	   15    6(40%)     9(60%) 205.189.33.236/30   29     13
   3915	   39   22(56%)     3(7%)  206.86.37/24        41      3
   6097	    4    0(0%)      4(100%)206.152.41/24       37      8
   3493	   88   76(86%)    12(13%) 206.167.88/24       26     15
     27	   12    8(66%)     1(8%)  206.196.190/24      24     16
    701	  364  288(79%)     7(1%)  207.79.80.0/26      2     114
   6379	   45   11(24%)    37(82%) 207.135.96/24       23     19
   5646	    3    2(66%)     1(33%) 207.227.0/24        21     20
   3561	  353  256(72%)    10(2%)  208.151.215/24      19     21
   2548	   40   37(92%)     3(7%)  209.116.192/24      40      5