Junos OS

Hello everyone.

I got MX running BNG services with DHCP authorization. All traceoptions are turned off and syslog server is configured. But i got jdhcpd_era_discover.log file rising in size and being rotated. So i just wondering is it necessary or i can turn it off somehow?

Hi,

Event Rate Analyzer (ERA) is a Subscriber Login Packet Overload Protection mechanism.

ERA basically is in-built overload protection mechanism (known as ERA or event rate analyser) that monitors the incoming login packets, and admits only what the system is capable of handling in accordance with the prevailing load on the system, while discarding the excess packets that the system cannot handle.  By shedding this excess load, the system is able to maintain optimal performance and prevent any degradation of login-completion-rate under overload.  The load throttling mechanism is light on resources, and is enabled by default. This load throttling mechanism operates on the RE and is secondary to what DDOS offers as a first level of defence for protection against high rates of incoming packets.

These logs are on by default, and there is no need for any configuration. They are non-intrusive and provide useful information about the logins. If you're pushing higher call per sec DHCP Discovery packets, lower the call per secs rate, the ERA monitoring should go off and hence the logging.

Thanks for great explanation!

Hello. 

Nowhere in Juniper Knowledge Base I could't find detailed information about Event Rate Analyzer (ERA)
You have well explained how it works, but what are the values to trigger ERA? And can they be changed?
Can you please answer this question?
Thanks.

Hi,

In general, it is recommended that end user/opertator do not tweak or modify the default ERA parameters.

It is designed to be transparent to the end user thus the information may not directly be visible to user.

They are empirically determined and has been fine tuned over the years. Tuning ERA can result in unexpected / undesired behaviour unless you have environmental use case to modify the ERA value on your B-RAS. If so, please log a case with JTAC /with use case, to have these values tuned.

Will file KB later to give basic & general overview on ERA function.

Did you file/write the KB for ERA?

Yes was this written i can't seem to find it. I have EX4200s in VC that is getting clogged up by these in var and would love to just turn them off since its the only log killing the space. I've set log rotation to 2 because 3 of these take up 100mb 😮 which is alot in switch storage space. I would like to keep my other logs longer than 2 rotations. 

Thanks!

@xfxchilde33 Here you can find a PR for the EX platform

https://prsearch.juniper.net/InfoCenter/index?page=prcontent&id=PR1431201

Unfortunately it wants me to upgrade past the JTAC recommended for my EX4200:  Junos 12.3R12-S15 / 15.1R7-S6

I guess I'm stuck 😞 Can't disable the log?