Routing Issue?

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Sep 16th, 2009
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Dear all,


please take a look at the following output:


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router#show logging

Sep 16 14:10:45: RT: SET_LAST_RDB for NET.NET.NET.NET/32

OLD rdb: via WAN1.WAN1.WAN1.WAN1

NEW rdb: via WAN2.WAN2.WAN2.WAN2

Sep 16 14:10:45: RT: SET_LAST_RDB for NET.NET.NET.NET/32

OLD rdb: via WAN2.WAN2.WAN2.WAN2

NEW rdb: via WAN1.WAN1.WAN1.WAN1

Sep 16 14:10:46: RT: SET_LAST_RDB for NET.NET.NET.NET/32

OLD rdb: via WAN1.WAN1.WAN1.WAN1

NEW rdb: via WAN2.WAN2.WAN2.WAN2

Sep 16 14:10:47: RT: SET_LAST_RDB for NET.NET.NET.NET/32

OLD rdb: via WAN2.WAN2.WAN2.WAN2

NEW rdb: via WAN1.WAN1.WAN1.WAN1

Sep 16 14:10:48: RT: SET_LAST_RDB for NET.NET.NET.NET/32

OLD rdb: via WAN1.WAN1.WAN1.WAN1

NEW rdb: via WAN2.WAN2.WAN2.WAN2

Sep 16 14:10:48: RT: SET_LAST_RDB for NET.NET.NET.NET/32

OLD rdb: via WAN2.WAN2.WAN2.WAN2

NEW rdb: via WAN1.WAN1.WAN1.WAN1

Sep 16 14:10:49: RT: SET_LAST_RDB for NET.NET.NET.NET/32

OLD rdb: via WAN1.WAN1.WAN1.WAN1

NEW rdb: via WAN2.WAN2.WAN2.WAN2

Sep 16 14:10:50: RT: SET_LAST_RDB for NET.NET.NET.NET/32

OLD rdb: via WAN2.WAN2.WAN2.WAN2

NEW rdb: via WAN1.WAN1.WAN1.WAN1

Sep 16 14:10:51: RT: SET_LAST_RDB for NET.NET.NET.NET/32

OLD rdb: via WAN1.WAN1.WAN1.WAN1

NEW rdb: via WAN2.WAN2.WAN2.WAN2

Sep 16 14:10:51: RT: SET_LAST_RDB for NET.NET.NET.NET/32

OLD rdb: via WAN2.WAN2.WAN2.WAN2

NEW rdb: via WAN1.WAN1.WAN1.WAN1

Sep 16 14:10:52: RT: SET_LAST_RDB for NET.NET.NET.NET/32

OLD rdb: via WAN1.WAN1.WAN1.WAN1

NEW rdb: via WAN2.WAN2.WAN2.WAN2


router# show ip route NET.NET.NET.NET

Routing entry for NET.NET.NET.NET/32

Known via "static", distance 1, metric 0

Redistributing via ospf 1

Advertised by ospf 1 subnets

Routing Descriptor Blocks:

WAN1.WAN1.WAN1.WAN1

Route metric is 0, traffic share count is 1

* WAN2.WAN2.WAN2.WAN2

Route metric is 0, traffic share count is 1


**************************************


DO you have any idea why it is showing this output?


Regards,


Mladen

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Giuseppe Larosa Wed, 09/16/2009 - 07:06
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Hello Mladen,

this looks like to be the output of debug ip routing for prefix net.net.net.net/32


the prefix is known via two static routes.


It appears the two static routes are swapping in the role of best path every 1 second.


I cannot say more.


Hope to help

Giuseppe



YANGCCIE4 Wed, 09/16/2009 - 07:35
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Hi, Mladen,


It seem you have redundant links to the host NET.NET.NET.NET/32, and one of link or (path) is not stable,or flapping.



mladentsvetkov Wed, 09/16/2009 - 23:58
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Thanks guys,


Let me tell you some more, maybe now you would be able to help:


The router is an ISR. The problem is the following:


"show ip route" shows a static route to NET.NET.NET.NET/32 via WAN2.WAN2.WAN2.WAN2, although this static route was never configured on the router manually. It was inserted long time ago via reverse route injection by a remote VPN. If this VPN connection is not available any more, why the router would continue to have the static route in the routing table?


When I do "clear ip route NET.NET.NET.NET 255.255.255.255" it shows the following:


RT: del NET.NET.NET.NET/32 via WAN2.WAN2.WAN2.WAN2, static metric [1/0]

RT: delete subnet route to NET.NET.NET.NET/32

RT: NET-RED NET.NET.NET.NET/32

RT: add NET.NET.NET.NET/32 via WAN2.WAN2.WAN2.WAN2, static metric [1/0]

RT: NET-RED NET.NET.NET.NET/32


It automatically inserts the route back into the routing table.


PLS Help


Regards


Mladen

mladentsvetkov Thu, 09/17/2009 - 00:38
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Here is something interesting:


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RRI: Fix support for VRFs and same CM on multi-ints

Symptoms: Reverse Route Injection (RRI) is not working as expected with VPN routing/forwarding (VRF) aware IPSec. Routes are created but may not be removed, leaving them stranded in the routing tables.


Conditions: This symptom occurs on routers that are running Cisco IOS Release 12.4 Mainline.


Workaround: There is no workaround

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YANGCCIE4 Thu, 09/17/2009 - 07:32
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When I do "clear ip route NET.NET.NET.NET 255.255.255.255" it shows the following:


Hi, how about try use #No ip route NET.NET.NET.NET 255.255.255.255,


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