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Halloween Special - MX480 toast!!!

FIB and RIB size on Juniper Networks MX480 router
Hashtag: #FIBRIBSizeMX480

Quite often I am being asked a question – how many active routes does MX480 router can process and forward traffic without collapsing itself or dropping traffic? Like almost all scalability questions – this one is not an exception and it does not have a simple answer. The number of prefixes in the FIB and RIB(s) of the particular router model – remember, there could be more than one RIB and routing tables and even routing instances in JUNOS highly depends on such things as:

  • the exact software version in use,
  • prefix lengths,
  • number of equal-cost path (next-hops),
  • network topology,
  • router configuration
  • etc...

Anyway, I have some hard limits for you, which were obtained during intense roasting of the platforms in our router torture chambers. For example here is some 'truth' that we squeezed from MX480 equipped with RE-S-2000. FIB capacity: ~1,400,000 prefixes | RIB capacity: ~4,000,000 prefixes

WARNING: Please, note that when approaching these numbers the router becomes extremely volatile and may crash at any moment. You WILL loose your telnet/ssh sessions to the router and SNMP monitoring. You will need the console connection or even power-cycle switch to recover.

In my experience 1 million prefixes for FIB and 2-3 millions for RIB are much safer numbers, which the M480 should be able to handle easily. But keep in mind that all of these numbers are shared between ALL routing instances, tables, RIBs (including in/out BGP RIBs for each peer) in a manner that is hard to predict. So if you have 1000 BGP peers, you may only have 1000 unique routes per peer. In fact this is much more complex than that – well it is complicated indeed, and I hope you just believe me.

Opt/Net Consulting B.V. can perform validation testing accordingly to your exact technical specifications and requirements, on demand, ;-), like in the case below...

Some output from the torture log:
FIB capacity test:
{master} /* hehe... let's see who's master now */

taras@MX480> show bgp summary                 

Groups: 3 Peers: 8 Down peers: 0
Table     Tot Paths  Act Paths Suppressed    History Damp State    Pending
inet.0      1420419    1420406          0          0          0       9117
inet.2            0          0          0          0          0          0
inet6.0          22          7          0          0          0          0
inet6.2           0          0          0          0          0          0

... truncated ...

Fig. 1 -- Throughput vs time line, the total throughput increases as prefixes populate the RIB and FIB

After reaching the point of maximum FIB size, the SSH and SNMP connectivity to the router dropped and console connection was used for RIB scalability tests.

RIB capacity test:

taras@MX480> show bgp summary                 

Groups: 2 Peers: 4 Down peers: 0

Table     Tot Paths  Act Paths Suppressed    History Damp State    Pending
inet.0      4849997    4849993          0          0          0          0
inet6.0           0          0          0          0          0          0
inet.2            0          0          0          0          0          0
inet6.2           0          0          0          0          0          0

... truncated ...

Between 4-5M routes BGP sessions dropped and rpd core dumped.

show log /var/log/messages
... truncated ...

Oct 31 19:51:07 MX480 dumpd: Core and context for rpd saved in /var/tmp/rpd.core-tarball.0.tgz

Have fun this Halloween but please,