Ike Hammers Texas Internet

September 13, 2008 Martin Brown

Ike made landfall near Galveston, Texas as a (high-end) category 2 hurricane around 02:00 CDT this morning. Today, we are all watching the destructive land-wake of the storm with our thoughts on those in its path.

The pattern of network outages seems consistent with other historical storms of Ike’s ilk. The counties around Galveston and Houston, TX (most notably Harris County) have suffered a slowly climbing number of network outages over the last day. We expect to see this number continue to climb as the secondary effects (e.g. power loss, UPS battery failure, generator fuel unavailability) of the storm hit the region.

We examined the withdrawals reported in BGP for prefixes (networks) in Arkansas, Florida, Louisiana, Mississippi, Oklahoma and Texas and notice that, aside from Texas, the coastal Gulf region has fared pretty well against Ike, so far. The Texan cities and counties immediately in the path of Ike are, however, definitely and noticeably suffering network connectivity failures.

Renesys routinely analyzes outage data in response to world events. We have learned to account for a certain ‘background noise’ of outages when examining global routing outage data. In short, in any grouping of prefixes at any time, there’s a likelihood that some prefixes are unavailable. Of course, these Ike-induced outages are obvious even without accounting for this baseline!

Recently, of the approximately 7000 prefixes which geolocate to Texas, a dozen or so of these are suffering outage at any one time. This is, therefore, a rough measure of the baseline of outages in Texas. Even before Ike’s landfall, the number of Texan prefixes suffering outage had climbed to three times the usual level (about 40). We don’t know the reasons for these particular outages, but could speculatively attribute these outages to damage from pre-landfall Ike or even intentional network shutdown.

 

 

From experience with the behaviour of outages in large-scale disasters, we know that onset of outages after natural disasters is usually noisy. As expected, there’s a generally increasing trend in networks suffering outage. For further visualization of the distribution of the outages, take a look at these maps of outage data, current as of an hour ago. You can load the outage data file into Google Earth. Alternatively visualize the outage data here via Google Maps:

 

View Larger Map

 

Affected cities, counties and organizations

To get a sense for the organizations affected in the initial aftermath of Ike, we can look at the top ten organizations, top five cities and top five counties, sorted by number of networks suffering an outage as of approximately 13:00 CDT. Notably, these do not account for the relative sizes of the organizations, cities or counties.

Organizations affected (prefix count)

  1. Schlumberger Limited (19)
  2. AT&T WorldNet Services (15)
  3. NASA/Johnson Space Center (12)
  4. Suddenlink Communications (10)
  5. Level 3 Communications, Inc. (10)
  6. Cebridge Connections (10)
  7. Internet America, Inc. (9)
  8. Comcast – Houston (9)
  9. NTT America, Inc. (8)
  10. Moore Concepts (6)

Cities affected (prefix count)

  1. Houston (110)
  2. Kingwood (14)
  3. Dallas (14)
  4. The Woodlands (10)
  5. Friendswood (5)

Counties affected (prefix count)

  1. Harris County 48201 (130)
  2. Dallas County 48113 (14)
  3. Montgomery County 48339 (13)
  4. Brazoria County 48039 (11)
  5. Fort Bend County 48157 (4)

In particular, Galveston, which is historically subject to hurricanes, has largely fallen off the Internet, including the University of Texas (129.109.0.0/16). The university hospital University of Texas Medical Branch appears to still be going strong and is reachable at a routed subprefix, 129.109.242.0/24, hosted by the State of Texas General Services Commission (AS 6922). Those hardy souls have won my respect and admiration!

More to come …

As with hurricanes Katrina, Rita and Gustav, we expect to see network outage counts continuing to increase over the coming days. Even after the nadir of the aftermath, restoration will be slow, and we don’t expect a return to normal internet connectivity in the region for several weeks, at least.

We will be watching to see the extent of the damage to the power infrastructure, typically a major determining factor for rescue and recovery operations. Nearly everyone in southeast Texas is going to be in the dark tonight, and the pace of restoration is going to depend on the extent of damage to the towers, transmission lines, and generation plants. We’ll issue an update when we have more data to share.

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