This article details how to determine the space utilized by a prefix in the Unified Forwarding Table (UFT) in QFX5100 Series devices.
The following table represents the memory utilized for programming a single prefix/route across route types and UFT profiles:
To determine the memory utilized for programming a single prefix, use the following procedure:
Note: For this example, the following hardware and Junos OS was used:
labroot@QFX51xx-R5> show version Feb 19 19:23:03 fpc0: -------------------------------------------------------------------------- Hostname: QFX51xx-R5 Model: qfx5100-48s-6q Junos: 14.1X53-D35.3
labroot@QFX51xx-R5> show version
Feb 19 19:23:03
fpc0:
--------------------------------------------------------------------------
Hostname: QFX51xx-R5
Model: qfx5100-48s-6q
Junos: 14.1X53-D35.3
Outputs with the default IPV4 host routes/before any IPV4 routes are advertised:
labroot@QFX51xx-R5> show pfe route summary hw ----> Displays routes installed in the on-chip hardware table Slot 0 Unit: 0 Profile active: lpm-profile Type Max Used Free % free ---------------------------------------------------- IPv4 Host 16384 14 16362 99.87 ----> Default free space IPv4 LPM 131072 5 131067 100.00 IPv4 Mcast 8192 0 8181 99.87 -----snip----- {master:0} labroot@QFX51xx-R5> show pfe route summary ----> Displays summary of Packet Forwarding Engine information Slot 0 IPv4 Route Tables: Index Routes Size(b) -------- ---------- ---------- Default 12 2352 ----> Default value 1 11 2152 -----snip-----
Outputs when one IPV4 host route is advertised:
{master:0} labroot@QFX51xx-R5> show pfe route summary hw ----> Displays routes installed in the on-chip hardware table Slot 0 Unit: 0 Profile active: lpm-profile Type Max Used Free % free ---------------------------------------------------- IPv4 Host 16384 15 16361 99.86 ----> Used value has increased by 1 and Free value has reduced by 1. IPv4 LPM 131072 5 131067 100.00 IPv4 Mcast 8192 0 8181 99.87 -----snip----- labroot@QFX51xx-R5> show pfe route summary ----> Displays a summary of Packet Forwarding Engine information. Slot 0 IPv4 Route Tables: Index Routes Size(b) -------- ---------- ---------- Default 13 2548 ----> Routes value has increased by 1 and Size(b) has increased by 196. 1 11 2152 -----snip-----
The same can be followed for other route types to determine their space utilization.
When the route threshold/space utilization exceeds the supported value, logs similar to the ones mentioned below are seen and hardware programming of new routes will fail:
Jan 17 08:50:49 2021 QFX51xx-R5 fpc0 _soc_alpm_128_insert: Unable to add newpivot to tcam Jan 17 08:50:49 2021 QFX51xx-R5 fpc0 (brcm_rt_ip_uc_lpm_install:LPM route add failed) Reason : Table full Jan 17 08:50:49 2021 QFX51xx-R5 fpc0 brcm_rt_ip_uc_entry_install Error: lpm ip route install failed vrf 1 ip 2007:0:500::/48 nh-swidx 131116 nh-hwidx 100045 Jan 17 08:50:49 2021 QFX51xx-R5 fpc0 _soc_alpm_128_insert: Unable to add newpivot to tcam labroot@QFX51xx-R5> show pfe route summary hw ------> Displays routes installed in the on-chip hardware table Slot 0 Unit: 0 Profile active: lpm-profile Type Max Used Free % free ---------------------------------------------------- IPv4 Host 16384 3560 11276 68.82 IPv4 LPM 131072 1527 129545 98.83 IPv4 Mcast 8192 209 5638 68.82 IPv6 Host 8192 565 5638 68.82 IPv6 LPM(< 64) 16385 26801 0 0.00 --------> No free space IPv6 LPM(> 64) 16385 172 0 0.00 --------> No free space IPv6 Mcast 4096 0 2820 68.85
Route scale is higher for IPV6, which lead to a lack of space in the hardware table.
labroot@QFX51xx-R5> show route summary ------> Displays summary statistics about the entries in the routing table ----- snip ------ inet6.0: 106429 destinations, 106732 routes (106429 active, 0 holddown, 0 hidden) Restart Complete Direct: 20 routes, 12 active Local: 18 routes, 18 active BGP: 106533 routes, 106238 active --------> BGP IPV6 routes are exceeding the threshold [default Limit - IPv6 unicast routes: 64,000 prefixes] IS-IS: 161 routes, 161 active ----- snip ------
Reduce the number of IPv6 routes learned either through route summarization or route aggregation to address the above issue.
UTF Profile Best Practice
If the host or LPM table stores the maximum number of entries for any given type of entry, the entire shared table will be full and will be unable to accommodate any entries of any other type. Different entry types occupy different amounts of memory. Visit Understanding the Unified Forwarding Table for more information.