If you have been experiencing slowness, this is why...

Ya started yesterday around 4am it seems. A lot of Cisco gear hitting the 512k route defaults and just dropping things.

http://www.bgpmon.net/what-caused-todays-internet-hiccup/

What caused the instability

Folks quickly started to speculate that this might be related to a known default limitation in older Cisco routers. These routers have a default limit of 512K routing entries in their TCAM memory. The BGP routing table size depends on a number of variables. The primary contributors are Internal, or local routes (more specific and VPN routes used only in the local AS) and External routes. These External routes are all the routes of everyone on the Internet, we sometimes refer to this as the global routing table of Default Free Zone (DFZ). For most networks on the Internet today the global routing table is the major contributor, while local routes vary from a few dozen to a few hundred. Only a small percentage of the networks have a few thousand Internal routes.

The size of the global routing table today (August 12 2014) is about 500k, this number marginally varies per provider. Let’s compare a few major ISP’s. The table below shows the number of IPv4 prefixes received per provider on a full feed BGP session.

The table above shows that depending on the provider and location the numbers differ slightly, but are indeed very close. It also shows that right now the number of prefixes is still several thousands under the 512,000 limit so it shouldn’t be an issue. However when we take a closer look at our BGP telemetry we see that starting at 07:48 UTC about 15,000 new prefixes were introduced into the global routing table.
Click to expand...
 
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We can't even keep such important routers upgraded to handle traffic. And we thought our physical infrastructure in this country was the main victim of neglect.
 
The TCAM recarve requires rebooting your router, at least Cisco. That's why providers have been reluctant. I know it's why I've been putting it off.

I still have a little room tbough
 
Hey,

We are running into this as well with our 6500/sup720-3bxl. We attempted to do a change last night, adjust the TCAM to ipv4 - 800k or 600k. The router didn't take the change and it put itself into a reboot loop until we removed the offending config.

http://www.cisco.com/c/en/us/suppor...-switches/116132-problem-catalyst6500-00.html

That article shows moving all the tables to ipv4, would that have fixed this issue or would it still run into a reboot issue? This is the error:

Last reload reason: FIB Protocol Allocation mismatch

The above article shows that when you run "mls cef maximum-routes ip 800" it will auto-allocate the remaining memory to ipv6, why would it have an allocation mismatch then?

Any help is much appreciated as we don't want to run into this in the middle of the day since our tables are 96%, trying to get a fix for this sooner rather than later...
 
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