MAC address table size

[yogsin_2001]

We are building a campus network with 4000-5000 users in near future and this value will increase in future, What should be the minimum MAC address table size for the distribution layer switch.

Thanks for the help

[Mark Malone]

Hi

You will be covered by most switches even a 2960 can support 8000 macs but you dont want that as a distribution switch ,38s can support 32000 , with that many users it depends as well what type of traffic etc how many servers and the traffic volume you expect rather than the amount of macs to pick a switch , the budget as well plays a major part due to the expense of kit and licenses if there routing instead of switching at lan level and what your using for your core switches , at a guess you want at least a 4000 series in there and probably 2 for redundancy depending on your design requirements

3850s output as below

Showing SDM Template Info

This is the Advanced (high scale) template.
  Number of VLANs:                                 4094
  Unicast MAC addresses:                           32768
  Overflow Unicast MAC addresses:                  512
  IGMP and Multicast groups:                       8192
  Overflow IGMP and Multicast groups:              512
  Directly connected routes:                       16384
  Indirect routes:                                 7168
  Security Access Control Entries:                 3072
  QoS Access Control Entries:                      3072
  Policy Based Routing ACEs:                       1024
  Netflow ACEs:                                    768
  Wireless Input Microflow policer ACEs:           256
  Wireless Output Microflow policer ACEs:          256
  Flow SPAN ACEs:                                  512
  Tunnels:                                         256
  Control Plane Entries:                           512
  Input Netflow flows:                             8192
  Output Netflow flows:                            16384
  SGT/DGT entries:                                 4096
  SGT/DGT Overflow entries:                        512

[Tony Anacan]

This is super helpful, thanks Mark! BTW, where or how do I get mac address-table capacity? So far, I've only found one source for a Nexus 1000 in the config guides. Thanks in advance!!!

[Joseph W. Doherty]

Part of you answer would depend on how many hosts a particular distribution layer switch would "see".

For example, in your campus of 4000 to 5000 users, assuming two MACs per user (i.e. PC and VoIP phone), that's up to 10K Macs, but all this would be L2 (indirectly) connected to just one distribution switch?

In my last job, our Enterprise network had about 100K users and about 5K Enterprise network devices.  Locations varied widely from small to fairly large.  However, don't recall ever worrying about, or hitting the limits of, MAC table sizes.

Perhaps, one reason we didn't hit such limits, as we almost never, per location, much needed to use a three layer topology, we often just used two layers, however the edge layer was often "large" chassis L3 switches (either the 6509 or 6513, sometimes populated with 96 port PoE line cards), which usually had no more than 1K hosts connected to each.