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asr1001 BGP Full-Table maximum Routes


what is the maximum amount of Routes which can be used in the FIB of an ASR1001?

The Document on states

"500,000 IPv4 or 500,000 IPv6 routes with 4GB Memory". What does this mean exactly ?

At the moment the full Routing Table/DFZ (Default Free-Zone) takes already over 452000 IPv4 Routes and over 12000 IPv6 Routes!

What happens if the maximum will be exceeded? Is this Router a good choice for using in a DFZ context?

Is there a show command which display the usage of the FIB?

Everyone's tags (6)

asr1001 BGP Full-Table maximum Routes


The maximum number of routes that can be used in the FIB of an ASR 1001 is 500,000 IPv4 or 500,000 IPv6 routes with 4GB Memory. This means you can have 500,000 IPv4 routes or 500,000 IPv6 routes in the FIB table of the ASR1K with 4GB of memory. To put it in simple words, it has to be ensured that the combine prefix count for both IPV4 & IPV6 should not exceed 500,000 in the FIB table. In your case since the total prefix count is around 464000 currently you need to be a little careful about the router's role.

If by any chance you exceed the total prefix count of 500,000 then the router would start reporting Memory Allocation Failure errors and as a result of insufficient memory CEF would get disabled automatically. This would lead to more problems.

If you believe at any time while deploying this device in DFZ context the combined (IPv4 + IPv6) prefix count may cross 500000 then you may consider using 8GB memory. This can help you to scale upto 1,000,000 IPv4 or IPv6 routes.

The command to look at the FIB table usage is "sh cef fib".

*Plz rate if this info was helpful.

Thanks & Regards,

Vignesh R P


asr1001 BGP Full-Table maximum Routes


i just want to get back on that reply: Are you really sure that adding more RAM would solve the limitation on maximum 512000 IPv4 routes???

Normally the FIB don't uses normal RAM, but some kind of "faster" ram like tcam on Switches.

So can i use a 1001 with 8 gb RAM in the internet Default Free Zone even when the total number of routes will exceed the 512000 limit? I want to use the router for routing and NOT as BGP Route-Reflector ?


asr1001 BGP Full-Table maximum Routes


meanwhile the IPv4 Routing table increased to 469682 and the IPv6 Routing Table increased to 15463 routes.

In summary 485145 Routes.

Would this overflow a default ASR1001 Router with 4 GB Ram?

Is it correct that the IPv6 Routes take four times more memory than the IPv4 routes?

As written before, it was recommended to upgrade the router to 8 GB Ram.

What would be the right Cisco product-ID?

M-ASR1K-1001-4GB=Cisco ASR1001 4GB DRAM,spare

Would that be sufficient? I assume that you get 2x2 GB DIMM Modules and with the two DIMM Modules already installed that would fill up to 8 Gbyte Ram?

Or do i have to order M-ASR1K-1001-8GB= Cisco ASR1001 8GB DRAM,spare

and remove the old modules?

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