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Sunday, November 3, 2019

Global BGP IPv4 table is around 800K in size

This week the global BGP IPv4 table is around 800,000 entries in size. I bring this up just to give you a head-up and say a “Wow”. I don’t want to make you worry about the number. This is not my intention.

I still remember the “old good time” when I had installed a BGP router (Cisco 3660) with 256 Megabytes of DRAM memory in year 2001. At that time, the BGP table is below 150,000 entries so that router worked well.

Screen capture of CIDR REPORT website on November 3, 2019

The size of router DRAM memory is not a problem today for most of BGP administrators. I had created a post about BGP memory consumption and had this rough estimate: every 100K BGP entries from a single peer requires 80 Megabytes of DRAM.

In other words, to store 800,000 entries today, we simply need around 800 Megabytes (that is 0.8 Gigabytes) DRAM for BGP protocol. This is simply a piece of cake for today’s router hardware.

Even an old Cisco ASR 1000 RP1 router with 4 Gigabytes DRAM supports “up to 1,000,000 IPv4 routes”. No worry on 800K BGP entries.

Taipei City view over Taipei Main Station (台北車站).
August 21, 2019

One more thing…

I just want to remind you when you are planning for BGP Route Reflectors. The memory size could be an issue because you must multiply the above estimates to the number of BGP protocol peers.

Again, with Cisco ASR 1000 RP1 router with 4 Gigabytes DRAM, BGP Route Reflector scalability is “up to 5,000,000 IPv4 routes”. If you are planning a route reflector using this model to have more than 5 BGP peers, you must examine the table size more carefully.

And by the way, IPv6 global BGP table size is around 80K this week. IPv6 table size is still not that huge compared to IPv4 today.

I am Li-Ji Hong. This is my blog “Show IP Protocols”. See you next time!

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