On Mon, Mar 10, 2014 at 02:18:57PM +0000, Justin Marshall wrote:

> > What does "show ip ospf route" look like from the ImageStream for
> > anything in that /24?  During the problem and while normal.
>
> Normal:
> N    x.x.213.0/26      [30] area: 0.0.0.0
>                            via x.x.214.74, eth1.206
> 
> During the problem it disappears from the "show ip ospf route"

Okay, the specific /26 route is probably being withdrawn from OSPF.

There must be a covering route sending that traffic to the Tower A
mikrotik in the absense of the specific /26 in order for the looping
traceroute to occur.  The Tower A mikrotik either doesn't have the
covering route so uses it's default, or has the covering route pointed
back to the ImageStream.  Possibly a leftover static route on the
ImageStream or the MikroTik at Tower A.

Are there any interface up or down messages in the logs on the Tower B
MikroTik?  Is STP enabled on the Tower B MikroTik's bridge interface?
Just grasping at staws.
 
> -----Original Message-----
> From: [email protected] 
> [mailto:[email protected]] On Behalf Of Justin Marshall
> Sent: Monday, March 10, 2014 9:51 AM
> To: Mikrotik discussions
> Subject: Re: [Mikrotik] OSPF Issue
> 
> > I may be interpreting your message incorrectly.  Could you clarify if
> > x.x.36.209 is an IP on an interface on the ImageStream?  Or is it on a 
> > router at Tower C which may also be connected to Tower A via a wireless 
> > link?  I suspect it is on the ImageStream.
> 
> Yes, the x.x.36.209 is an IP on an interface on the Imagestream...
> 
> > So, only the one subnet is falling out?  At the time that you get looping 
> > traceroutes for 213.1, other subnets run clean?
> 
> Yes, only the one subnet is falling out, all other subnets run clean
> 
> > Are you only looping for the one IP in that subnet or for all hosts in the 
> > subnet?
> 
> All IP's in that subnet are failing...
> 
> > What does "show ip ospf route" look like from the ImageStream for anything 
> > in that /24?  During the problem and while normal.
> 
> I will answer this as soon as I catch it again... It's so intermittent, hard 
> to catch it unless I stare at it...(most of the times I don't have to wait 
> too long)
> 
> > What does "/ip route print where dst-address in x.x.213.0/24" look like on 
> > MikroTik A and B?
> Tower A:
> [admin@Tower-VB_SBA] /ip route> print where dst-address in x.x.213.0/26
> Flags: X - disabled, A - active, D - dynamic, C - connect, S - static, r - 
> rip, b - bgp, o - ospf, m - mme, B - blackhole, U - unreachable, P - prohibit 
>  #      DST-ADDRESS        PREF-SRC        GATEWAY            DISTANCE
> 28 ADo  x.x.213.0/26                   198.172.214.66          110
> 
> Tower B:
> [admin@Tower-FP_Selvitz] /ip route> print where dst-address x.x.213.0/26
> Flags: X - disabled, A - active, D - dynamic, C - connect, S - static, r - 
> rip, b - bgp, o - ospf, m - mme, B - blackhole, U - unreachable, P - prohibit 
>  #      DST-ADDRESS        PREF-SRC        GATEWAY            DISTANCE 
> 
> > Is x.x.213.1 the OSPF router ID of your MikroTik at Tower B?  Have you made 
> > sure your all of your OSPF router IDs are all manually specified and unique 
> > within your network?
> 
> No, the router ID is x.x.214.66.  And Yes, all the OSPF router IDs are all 
> manually specified and unique.
> 
> > Does the problem resolve itself after a bit? how long? or do you have to 
> > take some action to clear it?
> 
> Yes, the problem resolves itself after about 8 to 10 seconds, haven't seen it 
> go much longer than that...
> 
> Thanks again for any input you can and have provided :) Justin
> 
> 
> 
> -----Original Message-----
> From: [email protected] 
> [mailto:[email protected]] On Behalf Of Scott Lambert
> Sent: Friday, March 07, 2014 5:15 PM
> To: Mikrotik discussions
> Subject: Re: [Mikrotik] OSPF Issue
> 
> On Wed, Mar 05, 2014 at 08:05:16PM +0000, Justin Marshall wrote:
> > Hi,
> > 
> > We are having an OSPF issue. At least i'm assuming it's an OSPF issue 
> > because there are no static routes involved.
> >
> > We have our core router (imagestream) connected via Fiber to a 
> > Mikrotik at Tower A, Which in turn is connected via 2 RB411AH's with 
> > Atheros AR922X's to a Mikrotik at Tower B.  Every 500-1000 pings we 
> > are loosing pings to 1 of the IP addresses on a bridge interface on 
> > the Mikrotik at Tower B.  When this happens I see an IP address that 
> > is bound to one of the interfaces on our imagestream, show up on an 
> > MTR like so...
> >
> 
> How is the wireless link from Tower A to Tower B configured?  Are the RB411s 
> bridged or do they participate in OSPF?  How are the wireless AP and station 
> interfaces configured?
> 
> What is the OSPF interface configuration across the wireless link?
> 
> Is the ImageStream up to date?
> 
> Are you losing OSPF neighbor associations on the MikroTiks?  Should show in 
> the MikroTik log or you can just see how long the OSPF neighbor association 
> has been installed.
> 
> > Host                                                         Loss%   Snt   
> > Last   Avg  Best  Wrst StDev
> > 1. 10.192.172.1                                               0.0%  3642    
> > 0.7   0.4   0.4  27.1   1.0
> > 2. x.x.99.1                                                   0.3%  3642    
> > 0.8   0.6   0.5  36.5   1.2
> > 3. x.x.214.74                                                 0.0%  3642    
> > 9.7   0.7   0.6  33.4   1.3
> >     x.x.36.209
> > 4. x.x.214.66                                                 0.0%  3642    
> > 8.0  10.3   0.7  75.1   9.1
> >     x.x.99.1
> > 5. x.x.213.1                                                  0.2%  3642   
> > 32.7  26.1   0.8 288.3  21.3
> >     x.x.36.209
> > 
> > 
> > This is how it should look:
> > Host                                                         Loss%   Snt   
> > Last   Avg  Best  Wrst StDev
> > 1. x.x.172.1                                                  0.0%     4    
> > 0.8   0.9   0.5   1.4   0.4
> > 2. x.x.99.1                                                   0.0%     4    
> > 0.7   0.8   0.6   1.0   0.2
> > 3. x.x.214.74                                                 0.0%     4    
> > 1.2   1.1   0.7   1.7   0.4
> > 4. x.x.214.66                                                 0.0%     3   
> > 29.8  15.5   5.7  29.8  12.7
> > 5. x.x.213.1                                                  0.0%     3   
> > 15.3  14.4  13.8  15.3   0.8
> > 
> >
> > Both Mikrotik's are on 6.7, running OSPF.  What we can't figure out is 
> > why this x.x.36.209 keeps showing up in the route. While this is 
> > happening, pings come back as: TTL exceeded.  Also we aren't loosing 
> > any pings to any other IP's on the Mikrotik in question at Tower B, 
> > nor are we loosing pings to any other IP addresses bound to that 
> > bridge interface.
> > 
> > The IP that we are loosing pings to is a public IP vs the others being 
> > private and not being in the /routing ospf networks.  This may or may 
> > not be relevant.  There is also no NAT involved whatsoever.
> 
> I may be interpreting your message incorrectly.  Could you clarify if
> x.x.36.209 is an IP on an interface on the ImageStream?  Or is it on a router 
> at Tower C which may also be connected to Tower A via a wireless link?  I 
> suspect it is on the ImageStream.
> 
> So, only the one subnet is falling out?  At the time that you get looping 
> traceroutes for 213.1, other subnets run clean?
> 
> Are you only looping for the one IP in that subnet or for all hosts in the 
> subnet?
> 
> What does "show ip ospf route" look like from the ImageStream for anything in 
> that /24?  During the problem and while normal.
> 
> What does "/ip route print where dst-address in x.x.213.0/24" look like on 
> MikroTik A and B?
> 
> Is x.x.213.1 the OSPF router ID of your MikroTik at Tower B?  Have you made 
> sure your all of your OSPF router IDs are all manually specified and unique 
> within your network?
> 
> Does the problem resolve itself after a bit? how long? or do you have to take 
> some action to clear it?
> 
> RouterOS 6.x has been better for us than 5.x for wierd OSPF issues.
> But it still seems a bit delicate.  Especially if you have a misconfiguration 
> somewhere or the wrong OSPF network type on a wireless bridge.
> 
> -- 
> Scott Lambert                    KC5MLE                       Unix SysAdmin
> [email protected]
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-- 
Scott Lambert                    KC5MLE                       Unix SysAdmin
[email protected]

How to be a "computer expert," http://www.xkcd.com/627/

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