What are "IP host entries" on a Nexus 9K line card?

[modular182]

I was looking at a datasheet for Nexus 9500 line cards. In it it had a table listing the number of "IP host entries" each card could hold. Are IP host entries ARP entries in the ARP table? When I think of "ip host" I think of the IOS command that allows you to assign an IP to a string so that the router/switch can resolve it without performing a dns query... which is why I'm confused over "IP host entries". Thanks!

[marce1000]

 - Take a look at this paragraph which kind of explains the 'use for' related to IP Host Entries : https://www.cisco.com/c/en/us/products/collateral/switches/nexus-9000-series-switches/white-paper-c11-729987.html#_Toc435046313

 M.

[Jon Marshall]

As far as I know the IP host entries are the IP host routes as opposed to the prefix routes in LPM. 

Jon

[modular182]

But aren't IP host routes routes that are added to the routing table for directly connected interfaces? For instance, if you have a router and you configure an interface on that router with a 10.1.1.1 IP address the router will put an IP host route in the route table for 10.1.1.1. If I'm correct here then why would a line card on a N9K need the ability to have 208K IP host routes per line card? It doesn't seem possible to assign 208K IPs to the 16/32/48 interfaces on a single line card. Thanks for taking the time to help me!

[Jon Marshall · Accepted solution]

From the link @marce1000 posted - 

"Inside the L3 lookup logic on the line card NFE, the destination IP address (DIP) is used for search in the L3 host table. This table stores forwarding entries for directly attached hosts or learned/32 host routes. If the DIP matches an entry in the host table, the entry indicates the destination port, next-hop MAC address and egress VLAN. If there is no match to the DIP in the host table, the packet will be forwarded to fabric module where the longest prefix match (LPM) lookup is performed in the LPM routing table."

there could be a lot of directly attached hosts or hosts on switches connected at L2 to the Nexus switch.

Jon

[modular182]

Very cool! This makes sense to me. Really appreciate it Jon!