The articles provide detail on how the space in "show pfe route summary hw" output is calculated for prefixes

The KB explains the details on how to calculate the space consumed  by host prefixes seen from "show pfe route summary hw"

• Kindly consider below output to check how the space is calculated

labroot@JTAC> show pfe route summary hw

Slot 0

Unit: 0

Profile active: custom-profile

Type      Max    Used   Free   % free

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

IPv4 Host    8192   3584   42    0.51.  >>>>>>>>>>>

IPv4 LPM    294912  162984  131928  44.73

IPv4 Mcast   4096   0     21    0.51

IPv6 Host    4096   2283   21    0.51

IPv6 LPM(< 64) 49152   31988   17055   34.70

IPv6 LPM(> 64) 49152   109    17055   34.70

IPv6 Mcast   2048   0     11    0.54

• The IPV4 host, IPV6 host, IPV4 Mcast and IPV6 Mcast use the same bank for storing the host prefixes
• IPV4 host uses one index/entries for each prefix.
• IPV6 host and IPV4 Mcast uses 2 index/entries for each prefix.
• IPV6 Mcast uses 4 indexes/entries for each prefix.

In our case we see the total space is 8192 for all the 4 banks combined which includes space for IPV4/V6/Multicast

1. Since each IPV6 host entries consumes 2 index, the space for IPV6 shows as 4096 which is half of the total bank value 8192.
2. Please note the 4096 seen on the IPV6 host is not addition to IPV4 value seen 8192.

Analysis of the  table :

>>Based on the output we see the total space is 8192

>>Out of which we have already 3584 used by IPV4 host and 2283 used for IPV6 

>>Sine each IPV6 uses 2 index , the total index used by IPV6 in our case is 2x2283 = 4566 

>>so now we have IPV6 using total of 4566 indexe's and IPV4 using 3584 which in total is = 3584 +4566 = 8150

Free space= total space[8192] - used space[ 3584 +4566 = 8150] = 42 

The 42 is the free available index in whole which can either hold 42 IPV4 entries or 21 IPV6 entries .