Please explain "Routed Clients" in table with Supported Models L3 switches

cld
Comes here often

Please explain "Routed Clients" in table with Supported Models L3 switches

The Meraki document "MS Layer 3 Switching and Routing" contains a table with supported models. 

Can someone explain the meaning of "Routed Clients" in this table?

For MS250 the routed clients number in the table is 4096.  We have an MS250 in our network. We have not configured layer 3 settings yet. As we are having significantly more than 4096 clients in our network (>5000), I am worried that we could get into trouble when activating L3 routing on the MS250.

https://documentation.meraki.com/MS/Layer_3_Switching/MS_Layer_3_Switching_and_Routing#Configuring_S...

3 REPLIES 3
ww
Kind of a big deal
Kind of a big deal

Re: Please explain "Routed Clients" in table with Supported Models L3 switches

Sound like the limit of the arp table

Bruce
Kind of a big deal

Re: Please explain "Routed Clients" in table with Supported Models L3 switches

Yep, I’d agree, sounds like the MAC address table size. So effectively this is the number of devices that the switch can know of from all of its SVIs (Layer 3 interfaces). If you exceed this figure then you’ll experience flooding of unicast packets. 

 

If a client sits the other side of another Layer 3 hop then the switch doesn’t need to know it’s MAC address, only the MAC address for the next hop. So as long as your 5,000+ clients aren’t all using the MS250 as their Layer 3 gateway then you should be fine - if they are all using the MS250 as their Layer 3 gateway then you may hit flooding issues (might be time for a switch upgrade).

 

EDIT: I think I explained a MAC address table well, but it’s not actually the same as the ARP table that @ww mentions. Since it’s referenced in a Layer 3 document, the ARP table makes more sense as it’s more aligned with Layer 3 - similar but different. If it’s the ARP table then it will still be a limit on clients from Layer 3 interfaces, but might result in extra ARP broadcasts (instead of flooding).

cld
Comes here often

Re: Please explain "Routed Clients" in table with Supported Models L3 switches

@Bruce 

I am quite sure the "Routed Clients" number is not the maximum size of the MAC address table. In the Meraki MS250 Data Sheet (https://meraki.cisco.com/lib/pdf/meraki_datasheet_ms250.pdf) one can read: "MAC forwarding entries: 16K on 24-port models, 32K on 48-port models". These numbers must be the maximum size of the MAC address table.

 

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