Max ARP in a 6500 or 3560

lawrence · ‎11-23-2009

I have an applications that will be using roughly 16k-64k IP addresses directly connected to a switch, That is .1/24 will be assigned on the switch(or router) and the full subnet will be used by hosts.

These can be broken into groups of 32 class Cs per "set" eq 16k ips per "set"(one vlan per class C) or can be all combined on one device either is fine.

I was originally looking at a a 3560 however after looking at tcam utilization im unclear if this platform will support that high a number of IPs. However I am a little unclear on exactly how the tcam util and actaul arp entries link.

In the 6500 i am unable to identify what the max number of arp entries it could hold are, i understand the arp table and adjacency table are closely linked so they would affect each other i believe?

How can i determine max supported arp entries?

thank you

Jon Marshall · ‎11-23-2009

lawrence@sporkton.com
I have an applications that will be using roughly 16k-64k IP addresses directly connected to a switch, That is .1/24 will be assigned on the switch(or router)  and the full subnet will be used by hosts.
These can be broken into groups of 32 class Cs per "set" eq 16k ips per "set"(one vlan per class C) or can be all combined on one device either is fine. 
I was originally looking at a a 3560 however after looking at tcam utilization im unclear if this platform will support that high a number of IPs. However I am a little unclear on exactly how the tcam util and actaul arp entries link.
In the 6500 i am unable to identify what the max number of arp entries it could hold are, i understand the arp table and adjacency table are closely linked so they would affect each other i believe?
How can i determine max supported arp entries?
thank you

Lawrence

The data sheets are very specific on this -

3560 switches support up to 12000 mac addresses

6500 with supervisor sup-7203b/3bxl support up to 64000 mac addresses

6500 with sup-s720-10g-3c/3cxl support up to 96000 mac addresses

Jon

lawrence · ‎11-23-2009

mac-address implies layer2 switching, i am doing more than layer2 switching. I am doing locally connected routing.

meaning

i typically link mac address with the mac-address-table, here i am looking at the arp.

lawrence · ‎11-23-2009

OK I think i figured it out

after i loaded more than ~6k arp entries the switch started tanking the cpu on the 3560, unable to fully test on a 6500 though. the only way to get the 12k mac that the datasheet specs(for 3560) is if you use the sdm "vlan" which creates high number of mac addresses but lowers your tcam allocation for unicast directly connected routes which is what arp entries show up as in the tcam it seems.

on the 3560 i got

#sho mac address-table count

Mac Entries for Vlan 1:

---------------------------

Dynamic Address Count : 13

Static Address Count : 0

Total Mac Addresses : 13

Mac Entries for Vlan 860:

---------------------------

Dynamic Address Count : 3

Static Address Count : 0

Total Mac Addresses : 3

Total Mac Address Space Available: 6105

#not sure exacly why this is different from

#the tcam part, but its different by 49, unable to find that number anywhere

also from show plat tcam util

IPv4 unicast directly-connected routes: 6144/6144 14/14 # here 14 ends up being the number of arp entries i noticed,

as for the 6500 i got the below, however this seems to be an accurate count of the mac arp/macs but the allocated mac count here is NOT representative of actual arp entries. i am still working out some of the details on that.

6509#sho mac-address-table count

MAC Entries for all vlans :

Dynamic Address Count: 326

Static Address (User-defined) Count: 415

Total MAC Addresses In Use: 741

Total MAC Addresses Available: 65536