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djsmith
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SNMP issues with BGP router

Thu Jun 17, 2010 3:52 am

I've noticed a few posters having trouble with enabling SNMP in the The Dude for routers that have a large number of probable entries (e.g. large routing tables). No resolutions have been posted that I could find.

sergejs advised me not to download the routing table http://forum.mikrotik.com/viewtopic.php?f=2&t=42566 which makes sense.

Is it possible to configre The Dude to not download the routing table? What are we able to configure when it comes to The Dude and SNMP data gathering?
 
lebowski
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Re: SNMP issues with BGP router

Thu Jun 17, 2010 8:14 am

That is a good one, I think you can disable SNMP download of the routing table for a Cisco.

Are you certain the dude is downloading the whole BGP routing table? If so how often?

Right now I don't see any performance issues... are you speaking of RB?
 
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gsandul
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Re: SNMP issues with BGP router

Thu Jun 17, 2010 9:28 am

You can have a problem when dude is trying to gownload the whole routing table. The router may have 100% CPU. My friend, is working on ISP now, and has such a problem with Dude and BGP router.
You can not disable routing download on Dude, but you can disable access to routing table on device.
In case of cisco check this document.
http://www.cisco.com/en/US/tech/tk648/t ... 48e6.shtml
 
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gsandul
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Re: SNMP issues with BGP router

Thu Jun 17, 2010 9:49 am

May add to previous post.
The Dude will download the whole routing table in any case, because it has to construct, and refresh from time to time this table
routing.JPG
Hope you can disable access to some SNMP OID's (routing table in your case) on RouterOS 4.5.
You do not have the required permissions to view the files attached to this post.
 
djsmith
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Re: SNMP issues with BGP router

Thu Jun 17, 2010 4:34 pm

I'm using routerOS 4.5 on a Dell server. Yes, The Dude is grabbing (or trying to grab) the whole table (I can see the entries under the SNMP Routes tab in The Dude). I haven't seen the router generate much in the way of CPU usage, however I'm monitoring it with The Dude and the CPU data gathering appears to come after the route table. If I enable a CPU service check for the device it often times out and puts the router into orange status in The Dude. This is what alerted me to the problem in the first place.

An snmpwalk of the router times out at 'random' points but the router CPU doesn't go over 10% (monitored from the winbox system resources window).

So, now I have the problem that I either need routerOS to not respond to SNMP routing queries, or get The Dude to not ask for them in the first place.

I suspect I'll get both support parties pointing to each other as the culprit and no solution..
 
lebowski
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Re: SNMP issues with BGP router

Thu Jun 17, 2010 6:53 pm

On a cisco 2821 when I open the snmp routing tab for my BGP router I see the cpu of the router go up to about 16% for SNMP and the total cpu hit about 50%. No wonder I never saw the trouble but since I don't need the BGP route in the dude, I will use the instructions for blocking based on the Cisco link provided by gsandul.

I applied the cutdown view and BGP routes no longer show up...

[edit - You will notice my tongue has the best of intentions but it trips sometimes.]
Last edited by lebowski on Sat Jun 19, 2010 2:28 am, edited 1 time in total.
 
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gsandul
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Re: SNMP issues with BGP router

Fri Jun 18, 2010 10:18 am

Hi, lebowski.
Do you have the whole internet routing table from BGP peers on your 2821?

I was talking about 100% CPU on a cisco 7206VXR core ISP router and this router has the whole internet routing table.
The same problem I had when I also was working on ISP, it apeared from time to time after we started using Dude. The quick solution was to disable/enable SNMP on a router, then, dude had no responce from router and stoped to query the table.
But the correct solution was to follow the instruction which I had provided in cisco URL and to disable some access to routing table.
The same solution should be applied when you have, many virtual interfaces, for example PPTP users.
 
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sioannou
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Re: SNMP issues with BGP router

Fri Jun 18, 2010 12:50 pm

Hello guys,

This affects the BGP stability on the RouterOS as well. It might not fail within 30 or 60 days of operation but it will fail at somepoint. I used to have that problem until I disabled the snmp on the RouterOS and then disabled the RouterOS querying on the dude as well.

Sotiris
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lebowski
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Re: SNMP issues with BGP router

Sat Jun 19, 2010 2:31 am

We have about 280,000 routes. I am not sure what the total number is...

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