[f-nsp] MLX Route issues after 5.4.0d upgrade

[Eldon Koyle]

What does 'show ip bgp routes detail 74.1.1.34' give you on the bad
path?  Hopefully that will at least tell you which router is
redistributing that route.  Is it possible that a router somewhere was
configured to redistribute OSPF routes into BGP?

-- 
Eldon Koyle
Information Technology
Utah State University
-- 
A fanatic is one who can't change his mind and won't change the subject.
		-- Winston Churchill

On  Oct 25 15:43-0400, James Cornman wrote:
> Hello,
> 
> I've come across some strange routing on an MLX8 (NI-MLX-MR) where the next
> hop for a route that is learned via BGP is overwritten by an OSPF neighbor.
> The routes are cycling every 10 seconds or so as well.
> 
> IE: 74.1.1.0/24 announced from a customer over 208.123.123.0/30 (customer
> is .2 and we're .1). Arbitrarily, the next hop will be overwritten with a
> next-hop IP of another downstream router in the network, say, 69.123.123.2.
> That OSPF neighbor is an NSSA in a area 4. The odd thing is that the
> redundant pair for this device was upgraded 60 days ago and hasn't shown
> these symptoms so it seems very safe to upgrade. Its as if that neighbor's
> advertisement for the next hop, learned by way of its redundant connection
> to a different device, is being seen as better than the directly connected
> neighbor. Upping the OSPF cost to that downstream site seems to band-aid
> the issue but it seems that this should not be occurring at all.
> 
> This only started occurring after upgrading from 5.3f to 5.4d. No other
> topology changes were introduced at the same time. I'm curious if anyone
> else has seen strange behavior like this. Totally seems like a bug of some
> sort for which I'll try to convey to Brocade.
> 
> Bad path:
> 
> SSH at CSR1.LGA1#show ip route 74.1.1.34
> Type Codes - B:BGP D:Connected I:ISIS O:OSPF R:RIP S:Static; Cost -
> Dist/Metric
> BGP  Codes - i:iBGP e:eBGP
> ISIS Codes - L1:Level-1 L2:Level-2
> OSPF Codes - i:Inter Area 1:External Type 1 2:External Type 2 s:Sham Link
> STATIC Codes - d:DHCPv6
>         Destination        Gateway         Port          Cost          Type
> Uptime src-vrf
> 1       74.1.1.0/24    69.123.123.2   ve 47         200/0         Bi   0m7s
>   -
> 
> OSPF Neighbor -- the downstream site doesnt even run BGP yet this route is
> learned via BGP.
> 
> 
> Good path:
> 
> SSH at CSR1.LGA1#show ip route 74.1.1.34
> Type Codes - B:BGP D:Connected I:ISIS O:OSPF R:RIP S:Static; Cost -
> Dist/Metric
> BGP  Codes - i:iBGP e:eBGP
> ISIS Codes - L1:Level-1 L2:Level-2
> OSPF Codes - i:Inter Area 1:External Type 1 2:External Type 2 s:Sham Link
> STATIC Codes - d:DHCPv6
>         Destination        Gateway         Port          Cost          Type
> Uptime src-vrf
> 1       74.1.1.0/24    208.123.123.2  ve 239        200/0         Bi
> 2m24s   -
> 
> The end customer's BGP advertisement.
> 
> 
> -James
> 
> -- 
> 
> *James Cornman*
> 
> jcornman at atlanticmetro.net
> 212.792.9950
> *
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