This article talks about one scenario where LPM route installation fails and how to troubleshoot the issue.
When the LPM profile is not enabled on the device, below logs might be reported(one possible scenario).
Feb 14 02:14:51 QFX5100: %PFE-3: fpc0 brcm_rt_ip_uc_lpm_install:1404(LPM route add failed) Reason : Table full unit 0
Feb 14 02:14:51 QFX5100 : %PFE-3: fpc0 brcm_rt_ip_uc_entry_install:1262brcm_rt_ip_uc_entry_install Error: lpm ip route install failed vrf 1 ip 171.82.10/24 nh-swidx 131093 nh-hwidx 100021
Check the show chassis forwarding-options for the UFT profiles currently enabled on the device.
>>>>Currently the device is using default-profile -----------l2-profile-three which has default limits of (MAC: 160K L3-host: 144K LPM: 16K)
root@QFX5100> show chassis forwarding-options
fpc0:
--------------------------------------------------------------------------
UFT Configuration:
l2-profile-three. (MAC: 160K L3-host: 144K LPM: 16K) (default)
num-65-127-prefix = 1K
>>>>Check for the free space for LPM routes with default profile enabled:-
root@QFX5100> show pfe route summary hw
Slot 0
Unit: 0
Profile active: l2-profile-three
Type Max Used Free % free
----------------------------------------------------
IPv4 Host 147456 414 147030 99.71
IPv4 LPM 12288 12251 31 0.25 <<<<<The current free space is only 0.25%
IPv4 Mcast 73728 0 73515 99.71
IPv6 Host 73728 6 73515 99.71
IPv6 LPM(< 64) 6144 3 16 0.26
IPv6 LPM(> 64) 1024 0 1024 100.00
IPv6 Mcast 36864 0 36758 99.71
>>>>In order to increase the space for LPM routes, you will have to configure lpm-profile under chassis forwarding-options as below:-
root@QFX5100#set chassis forwarding-options lpm-profile
After enabling the lpm-profile the space is updated as below:-
Profile active: lpm-profile
IPv4 Host 16384 410 15962 97.42
IPv4 LPM 131072 12253 118819 90.65 <<<<<<<<<< after enabling lpm-profile the free space is updated to 90.65%
IPv4 Mcast 8192 0 7981 97.42
IPv6 Host 8192 6 7981 97.42
IPv6 LPM(< 64) 16385 3 16380 99.97
IPv6 LPM(> 64) 16385 2 16380 99.97
IPv6 Mcast 4096 0 3991 97.44