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Looks like with all the mass IP grabs as well as subletting of space, things have finally hit the 512K mark.

Anyone on the raw end of an upstream router that ran out of route space?

How do most routers handle route exhaustion? Does it still operate, just with a < full table? Or does it break? Or does it end up doing a lot of the routing in software?

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closed as too broad by EEAA, TomTom, joeqwerty, MichelZ, Michael Hampton Aug 13 at 13:11

There are either too many possible answers, or good answers would be too long for this format. Please add details to narrow the answer set or to isolate an issue that can be answered in a few paragraphs.If this question can be reworded to fit the rules in the help center, please edit the question.

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up vote 4 down vote accepted

There is a simple fix for this, at least when it comes to the most popular Cisco routers:

mls cef maximum-routes ip 768

This requires a reboot.

Also see Cisco's documentation about adjusting the TCAM to allocate more IPv4 space (and less IPv6): http://www.cisco.com/c/en/us/support/docs/switches/catalyst-6500-series-switches/117712-problemsolution-cat6500-00.html

Source: http://packetlife.net/blog/2014/may/6/global-ipv4-routing-table-hits-500k-routes/

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