Re: CBAC and Local Policy : Why OSPF neighbor relation dead ?

From: Edouard Zorrilla (ezorrilla@tsf.com.pe)
Date: Thu Feb 12 2009 - 18:46:34 ARST


Good, it works :

Excluding OSPF from the local routing policy:

My route-map adding "match ip address 122":

Rack1R4#sh run | sec route-map
ip local policy route-map POL-LOCAL
route-map POL-LOCAL permit 10
 match ip address 122
 set interface Loopback0
Rack1R4#

So ACL 122 is like:

Rack1R4#sh ip access-lists 122
Extended IP access list 122
    10 deny ospf any any (24 matches)
    20 permit ip any any (1 match)
Rack1R4#

And then :

Rack1R6#
000147: *Feb 12 21:34:55.944: %OSPF-5-ADJCHG: Process 1, Nbr 150.1.4.4 on
GigabitEthernet0/0 from EXSTART to DOWN, Neighbor Down: Too many
retransmissions
Rack1R6#
Rack1R6#
Rack1R6#sh ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
150.1.4.4 1 DOWN/DROTHER - 183.1.46.4
GigabitEthernet0/0
Rack1R6#
000148: *Feb 12 21:35:55.944: %OSPF-5-ADJCHG: Process 1, Nbr 150.1.4.4 on
GigabitEthernet0/0 from DOWN to DOWN, Neighbor Down: Ignore timer expired
000149: *Feb 12 21:35:55.948: %OSPF-5-ADJCHG: Process 1, Nbr 150.1.4.4 on
GigabitEthernet0/0 from LOADING to FULL, Loading Done
Rack1R6#
Neighbor ID Pri State Dead Time Address Interface
150.1.4.4 1 FULL/DROTHER 00:00:37 183.1.46.4
GigabitEthernet0/0
Rack1R6#
000150: *Feb 12 21:36:02.160: %BGP-5-ADJCHANGE: neighbor 183.1.0.3 Up
Rack1R6#

OSPF relationship goes up.

Thanks to everydoby,

Regards

  ----- Original Message -----
  From: paul cosgrove
  To: Edouard Zorrilla
  Cc: security@groupstudy.com ; ccielab@groupstudy.com
  Sent: Thursday, February 12, 2009 2:42 PM
  Subject: Re: CBAC and Local Policy : Why OSPF neighbor relation dead ?

  Hi Edouard,

  Exclude OSPF from your policy routing. The packets will have a TTL of 1 and
so it looks like they are being dropped when returning on the loopback. Even
if the TTL was higher, your outbound ACL does not permit OSPF.

  Paul.

  On Thu, Feb 12, 2009 at 6:50 PM, Edouard Zorrilla <ezorrilla@tsf.com.pe>
wrote:

    Just doing a lab and I run into this issue.

    My topology:

    R4(Gi0/0)---ethernet --- (Gi0/0)R6

    Rack1R4#sh run int gi0/0
    Building configuration...

    Current configuration : 232 bytes
    !
    interface GigabitEthernet0/0
     description Connected-to-SW1-Fa0/4
     ip address 183.1.46.4 255.255.255.0
     ip access-group inbound in
     ip access-group outbound out
     ip ospf message-digest-key 1 md5 CISCO
     duplex auto
     speed auto
    end

    Rack1R4#

    Rack1R4#sh ip access-lists outbound
    Extended IP access list outbound
       11 permit icmp any any reflect acl-ccie (113 matches)
       12 permit udp any any reflect acl-ccie (33 matches)
       20 permit tcp any any reflect acl-ccie (624 matches)
       30 deny ip any any log
    Rack1R4#

    Rack1R4#sh ip access-lists inbound
    Extended IP access list inbound
       9 permit icmp any any port-unreachable
       10 permit ospf any any (1258 matches)
       11 permit icmp any any time-exceeded (149 matches)
       12 permit icmp any any unreachable (14 matches)
       13 permit icmp any host 183.1.46.4 echo-reply (30 matches)
       20 evaluate acl-ccie
       30 deny ip any any log (31 matches)
    Rack1R4#

    It works fine, but If I need to push traffic out from the router R4 and
also
    need the Reflexive ACL to not drop the traffic that I originate from the
    router, like this one:

    Rack1R4#telnet 183.1.46.6
    Trying 183.1.46.6 ...
    Feb 12 18:23:37.857: %SEC-6-IPACCESSLOGP: list inbound denied tcp
    183.1.46.6(23) -> 183.1.46.4(64178), 1 packet
    Feb 12 18:23:39.857: %SEC-6-IPACCESSLOGP: list inbound denied tcp
    183.1.46.6(23) -> 183.1.46.4(64178), 1 packet
    % Connection reset by user
    Rack1R4

    Then I need to set a local policy pointing to any loopback (another
option
    could be adding more acls inside inbound access-list), in that way I make
my
    traffic Flow Throw through the router, and not to be originated from the
    router itself. Good so far.

    Then in R4:

    Rack1R4#
    route-map POL-LOCAL permit 10
     set interface Loopback0

    and

    Rack1R4(config)#ip local policy route-map POL-LOCAL

    Then in R4 I can telnet R6:

    Rack1R4#telnet 183.1.46.6
    Trying 183.1.46.6 ... Open
    User Access Verification

    Password:
    Rack1R6>

    But OSPF dies:
    -------------

    Rack1R4#sh ip ospf neighbor

    Neighbor ID Pri State Dead Time Address
Interface
    150.1.6.6 1 FULL/DR 00:00:38 183.1.46.6
    GigabitEthernet0/0
    150.1.5.5 0 FULL/ - 00:00:32 183.1.45.5
Serial0/2/0
    150.1.5.5 0 FULL/ - 00:01:39 183.1.0.5
    Serial0/3/0.345
    Rack1R4#

    and

    Rack1R6#sh ip ospf neighbor

    Neighbor ID Pri State Dead Time Address
Interface
    150.1.4.4 1 FULL/BDR 00:00:37 183.1.46.4
    GigabitEthernet0/0
    Rack1R6#

    In R6 I perform:
    ---------------------------------

    Rack1R6#clear ip ospf process
    Reset ALL OSPF processes? [no]: yes
    Rack1R6#
    Rack1R6#
    000119: *Feb 12 19:33:56.213: %OSPF-5-ADJCHG: Process 1, Nbr 150.1.4.4 on
    GigabitEthernet0/0 from FULL to DOWN, Neighbor Down: Interface down or
    detached
    Rack1R6#sh ip ospf neighbor

    Neighbor ID Pri State Dead Time Address
Interface
    150.1.4.4 1 EXSTART/DR 00:00:33 183.1.46.4
    GigabitEthernet0/0
    Rack1R6#

    Rack1R4#sh ip ospf neighbor

    Neighbor ID Pri State Dead Time Address
Interface
    150.1.6.6 1 EXCHANGE/BDR 00:00:39 183.1.46.6
    GigabitEthernet0/0
    150.1.5.5 0 FULL/ - 00:00:39 183.1.45.5
Serial0/2/0
    150.1.5.5 0 EXCHANGE/ - 00:01:59 183.1.0.5
    Serial0/3/0.345
    Rack1R4#

    Why OSPF neighbord relationship dead when I add local policy routing ? Any
one
    one an idea ?

    Regards

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