This article explains about BGP flaps due to route scale exceeding threshold and also provides details on how to monitor the route scale using SNMP

• The switch has over 2 million routes or more in its RIB table.

Switch> show route summary 

Autonomous system number: 20940

Router ID: 2.19.8.4

Maximum ECMP: 32

Highwater Mark (All time / Time averaged watermark)

  RIB unique destination routes: 1179129 at 2024-07-16 04:10:17 / 1168749

  RIB routes          : 2724836 at 2024-06-27 14:21:47 / 2158671 <<<<<<<<

  FIB routes          : 121018 at 2023-12-04 17:32:12 / 94418

  VRF type routing instances  : 0 at 2023-05-26 07:37:55

inet.0: 965101 destinations, 1703092 routes (959274 active, 90482 holddown, 101628 hidden)

       Direct:   54 routes,   54 active

        Local:   52 routes,   52 active

         BGP: 1702969 routes, 959153 active

       Static:   1 routes,   1 active

      Aggregate:   16 routes,   14 active

inet6.0: 204972 destinations, 461307 routes (200868 active, 20170 holddown, 62787 hidden)

       Direct:   53 routes,   53 active

        Local:   93 routes,   93 active

         BGP: 461157 routes, 200718 active

       Static:   1 routes,   1 active

      Aggregate:   2 routes,   2 active

        INET6:   1 routes,   1 active

{master:0}

• High memory usage on the Juniper device.

Switch> show system processes extensive |match rpd   

10556 root     94  0 2950M 2380M RUN   0 2093.9 73.88% rpd{rpd}. <<<<<

10556 root     22  0 2950M 2380M kqread  0 112.5H  3.96% rpd{bgpio-0-th}

10556 root     20  0 2950M 2380M kqread  1 927:59  0.00% rpd{TraceThread}

10556 root     20  0 2950M 2380M kqread  0 150:24  0.00% rpd{krtio-th}

{master:0}

Switch> show system processes extensive |match rpd   

10556 root     95  0 2950M 2380M CPU1   1 2093.9 75.39% rpd{rpd}. <<<<<

10556 root     22  0 2950M 2380M kqread  1 112.5H  3.86% rpd{bgpio-0-th}

10556 root     20  0 2950M 2380M kqread  0 927:59  0.00% rpd{TraceThread}

10556 root     20  0 2950M 2380M kqread  1 150:24  0.00% rpd{krtio-th}

We need to reduce the RIB table size As per below supported scale.

** Supported scaling on the device is:

• RIB IPv4: 2M
• RIB IPV6: 500K
• FIB IPV4: 262K
• FIB IPV6: 172K

These numbers have been tested on QFX5210, which is equivalent of AS7816 (both platforms use same chipset). 

We can use the MIB for monitoring the total number of routes. Here is the link to the MIB:

https://apps.juniper.net/mib-explorer/navigate?software=Junos%20OS&release=21.4R3&name=inetCidrRouteNumber&oid=1.3.6.1.2.1.4.24.6

18-10-2024 Article Created