Hi Guys.I am trying to learn BGP and I have been playing around with a BGP lab config using GNS3. It calls for different autonomous systems running different IGPs and these atonomous systems are connected via eBGP. iBGP is also running withing the AS. The router are are all connected via loop back addresses. To achieve full BGP connectivity the redistibute connected command is used under the BGP process on each router. There is no redistribution with IGPs. No filtering or router manipulaiton is being performed as yet.
There is a problem within the AS that is running EIGRP and iBGP. When i do the debug ip routing and debug bgp updates on these routers i see where the router's loopback is being learn by learn via iBGP and then withdrawn and the relearned via EIGRP and the flapping continues. I have shut down all outgoing connections from these routers and they are in essence connected back to back just now and the problem still continues.
I would love some advice on this issue. Thanks in advance.
Some configs are listed below.
-------R6------R7-------
R6#sho ver
Cisco IOS Software, 3700 Software (C3745-ADVENTERPRISEK9_IVS-M), Version 12.4(15)T8, RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2008 by Cisco Systems, Inc.
Compiled Mon 01-Dec-08 20:17 by prod_rel_team
ROM: ROMMON Emulation Microcode
ROM: 3700 Software (C3745-ADVENTERPRISEK9_IVS-M), Version 12.4(15)T8, RELEASE SOFTWARE (fc3)
R6 uptime is 3 days, 19 hours, 54 minutes
System returned to ROM by unknown reload cause - suspect boot_data[BOOT_COUNT] 0x0, BOOT_COUNT 0, BOOTDATA 19
System image file is "tftp://255.255.255.255/unknown"
This product contains cryptographic features and is subject to United
States and local country laws governing import, export, transfer and
use. Delivery of Cisco cryptographic products does not imply
third-party authority to import, export, distribute or use encryption.
Importers, exporters, distributors and users are responsible for
compliance with U.S. and local country laws. By using this product you
agree to comply with applicable laws and regulations. If you are unable
to comply with U.S. and local laws, return this product immediately.
A summary of U.S. laws governing Cisco cryptographic products may be found at:
http://www.cisco.com/wwl/export/crypto/tool/stqrg.html
If you require further assistance please contact us by sending email to
export@cisco.com.
Cisco 3745 (R7000) processor (revision 2.0) with 249856K/12288K bytes of memory.
Processor board ID FTX0945W0MY
R7000 CPU at 350MHz, Implementation 39, Rev 2.1, 256KB L2, 512KB L3 Cache
3 FastEthernet interfaces
DRAM configuration is 64 bits wide with parity enabled.
151K bytes of NVRAM.
16384K bytes of ATA System CompactFlash (Read/Write)
Configuration register is 0x2102
R6: sho run
!
interface Loopback0
ip address 6.6.6.6 255.255.255.255
!
interface FastEthernet0/0
ip address 192.168.46.6 255.255.255.0
shutdown
speed 100
full-duplex
!
interface FastEthernet0/1
ip address 192.168.56.6 255.255.255.0
shutdown
speed 100
full-duplex
!
interface FastEthernet1/0
ip address 192.168.67.6 255.255.255.0
duplex auto
speed auto
!
router eigrp 10
network 6.6.6.6 0.0.0.0
network 192.168.67.0
no auto-summary
!
router bgp 200
no synchronization
bgp log-neighbor-changes
redistribute connected
neighbor 4.4.4.4 remote-as 300
neighbor 4.4.4.4 ebgp-multihop 2
neighbor 4.4.4.4 update-source Loopback0
neighbor 5.5.5.5 remote-as 300
neighbor 5.5.5.5 ebgp-multihop 2
neighbor 5.5.5.5 update-source Loopback0
neighbor 7.7.7.7 remote-as 200
neighbor 7.7.7.7 update-source Loopback0
no auto-summary
!
ip forward-protocol nd
ip route 4.4.4.4 255.255.255.255 192.168.46.4
ip route 5.5.5.5 255.255.255.255 192.168.56.5
R7: sho run
!
interface Loopback0
ip address 7.7.7.7 255.255.255.255
!
interface FastEthernet0/0
ip address 192.168.67.7 255.255.255.0
speed 100
full-duplex
!
interface FastEthernet0/1
ip address 192.168.117.7 255.255.255.0
shutdown
duplex auto
speed auto
!
router eigrp 10
network 7.7.7.7 0.0.0.0
network 192.168.67.0
auto-summary
!
router bgp 200
no synchronization
bgp log-neighbor-changes
redistribute connected
neighbor 6.6.6.6 remote-as 200
neighbor 6.6.6.6 update-source Loopback0
neighbor 11.11.11.11 remote-as 400
neighbor 11.11.11.11 password VAULT
neighbor 11.11.11.11 ebgp-multihop 2
neighbor 11.11.11.11 update-source Loopback0
no auto-summary
!
ip forward-protocol nd
ip route 11.11.11.11 255.255.255.255 192.168.117.11
R6: debug ip routing and debug bgp updates
!
Mar 4 19:59:03.597: RT: del 7.7.7.7/32 via 7.7.7.7, bgp metric [200/0]
*Mar 4 19:59:03.601: RT: delete subnet route to 7.7.7.7/32
*Mar 4 19:59:03.601: RT: NET-RED 7.7.7.7/32
*Mar 4 19:59:03.617: RT: Try lookup less specific 7.7.7.7/32, default 1
*Mar 4 19:59:03.621: RT: Found major net on less specific 7.0.0.0/8
--More--
*Mar 4 19:59:30.257: RT: network 7.0.0.0 is now variably masked
*Mar 4 19:59:30.261: RT: add 7.7.7.7/32 via 7.7.7.7, bgp metric [200/0]
*Mar 4 19:59:30.265: RT: NET-RED 7.7.7.7/32
--More--
*Mar 4 19:59:35.369: RT: del 7.7.7.7/32 via 7.7.7.7, bgp metric [200/0]
*Mar 4 19:59:35.373: RT: delete subnet route to 7.7.7.7/32
*Mar 4 19:59:35.377: RT: NET-RED 7.7.7.7/32
*Mar 4 19:59:35.389: RT: Try lookup less specific 7.7.7.7/32, default 1
*Mar 4 19:59:35.393: RT: Found major net on less specific 7.0.0.0/8
*Mar 4 20:01:34.265: RT: network 7.0.0.0 is now variably masked
*Mar 4 20:01:34.269: RT: add 7.7.7.7/32 via 7.7.7.7, bgp metric [200/0]
*Mar 4 20:01:34.273: RT: NET-RED 7.7.7.7/32
--More--
*Mar 4 20:01:39.377: RT: del 7.7.7.7/32 via 7.7.7.7, bgp metric [200/0]
*Mar 4 20:01:39.381: RT: delete subnet route to 7.7.7.7/32
*Mar 4 20:01:39.381: RT: NET-RED 7.7.7.7/32
*Mar 4 20:01:39.397: RT: Try lookup less specific 7.7.7.7/32, default 1
*Mar 4 20:01:39.401: RT: Found major net on less specific 7.0.0.0/8
The following also appears in the logs
*Mar 4 20:23:23.137: RT: recursion error routing 7.7.7.7 - probable routing loop
*Mar 4 20:23:23.449: RT: recursion error routing 7.7.7.7 - probable routing loop
*Mar 4 20:23:23.917: RT: recursion error routing 7.7.7.7 - probable routing loop
*Mar 4 20:23:24.057: RT: recursion error routing 7.7.7.7 - probable routing loop
*Mar 4 20:23:24.065: RT: recursion error routing 7.7.7.7 - probable routing loop
--More--
*Mar 4 20:23:24.669: RT: recursion error routing 7.7.7.7 - probable routing loop
*Mar 4 20:23:25.289: RT: recursion error routing 7.7.7.7 - probable routing loop
--More--
*Mar 4 20:23:25.893: RT: recursion error routing 7.7.7.7 - probable routing loop
--More--
*Mar 4 20:23:27.737: RT: recursion error routing 7.7.7.7 - probable routing loop
*Mar 4 20:23:28.357: RT: recursion error routing 7.7.7.7 - probable routing loop
--More--
*Mar 4 20:23:32.633: RT: recursion error routing 7.7.7.7 - probable routing loop
*Mar 4 20:23:33.297: RT: recursion error routing 7.7.7.7 - probable routing loop
--More--
*Mar 4 20:23:38.825: RT: del 7.7.7.7/32 via 7.7.7.7, bgp metric [200/0]
*Mar 4 20:23:38.829: RT: delete subnet route to 7.7.7.7/32
*Mar 4 20:23:38.833: RT: NET-RED 7.7.7.7/32
*Mar 4 20:23:38.849: RT: Try lookup less specific 7.7.7.7/32, default 1
*Mar 4 20:23:38.849: RT: Found major net on less specific 7.0.0.0/8
Mar 4 20:44:05.952: BGP(0): no valid path for 7.7.7.7/32
*Mar 4 20:44:06.044: BGP(0): nettable_walker 7.7.7.7/32 no best path
*Mar 4 20:44:06.048: RT: del 7.7.7.7/32 via 7.7.7.7, bgp metric [200/0]
*Mar 4 20:44:06.048: RT: delete subnet route to 7.7.7.7/32
*Mar 4 20:44:06.052: RT: NET-RED 7.7.7.7/32
*Mar 4 20:44:06.068: RT: Try lookup less specific 7.7.7.7/32, default 1
*Mar 4 20:44:06.072: RT: Found major net on less specific 7.0.0.0/8
R6#
*Mar 4 20:44:31.300: BGP(0): Revise route installing 1 of 1 routes for 7.7.7.7/32 -> 7.7.7.7(main) to main IP table
*Mar 4 20:44:31.304: RT: network 7.0.0.0 is now variably masked
*Mar 4 20:44:31.308: RT: add 7.7.7.7/32 via 7.7.7.7, bgp metric [200/0]
*Mar 4 20:44:31.312: RT: NET-RED 7.7.7.7/32
R6#
*Mar 4 20:44:36.328: BGP(0): no valid path for 7.7.7.7/32
*Mar 4 20:44:36.444: BGP(0): nettable_walker 7.7.7.7/32 no best path
*Mar 4 20:44:36.448: RT: del 7.7.7.7/32 via 7.7.7.7, bgp metric [200/0]
*Mar 4 20:44:36.448: RT: delete subnet route to 7.7.7.7/32
*Mar 4 20:44:36.448: RT: NET-RED 7.7.7.7/32
*Mar 4 20:44:36.456: RT: Try lookup less specific 7.7.7.7/32, default 1
*Mar 4 20:44:36.456: RT: Found major net on less specific 7.0.0.0/8
R6#
*Mar 4 20:45:02.556: BGP(0): Revise route installing 1 of 1 routes for 7.7.7.7/32 -> 7.7.7.7(main) to main IP table
*Mar 4 20:45:02.560: RT: network 7.0.0.0 is now variably masked
*Mar 4 20:45:02.564: RT: add 7.7.7.7/32 via 7.7.7.7, bgp metric [200/0]
*Mar 4 20:45:02.568: RT: NET-RED 7.7.7.7/32
R6#
Thanks in advance.
Marlon
