03-27-2009 12:13 PM - edited 03-04-2019 04:07 AM
Hi,
We have eBGp with our SP and they are sending default to us. When we do a show ip bgp ne X.X.X.X received-routes the O/P says % Inbound soft reconfiguration not enabled on X.X.X.X.
If I do a Soft reconfiguration on the Inbound. It learns a whole lot of routes along with default even if i have a distribute list for the neighbor with deny any which looks like
neighbor X.X.X.X distribute-list 2 in
access-list 2 deny any
Please let me know
1. How do i get only the default.
2. What all events will trigger our SP's Border Gateway to stop sending the default.
Thanks in advance,
subra
03-27-2009 12:16 PM
Subra,
access-list 2 permit 0.0.0.0
access-list 2 deny any
Regards
03-27-2009 03:22 PM
Hi,
THanks for the info.
I get the following from the sh ip bgp neighbor
Network Next Hop Metric LocPrf Weight Path
r> 0.0.0.0 X.X.X.X 0 65535 i
What could be wrong now?
r -> rib failure.
I am running cat 4500. below is the show ver:
Cisco IOS Software, Catalyst 4500 L3 Switch Software (cat4500-ENTSERVICESK9-M), Version 12.2(46)SG, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2008 by Cisco Systems, Inc.
Compiled Fri 27-Jun-08 16:24 by prod_rel_team
Image text-base: 0x10000000, data-base: 0x11E3C0D8
ROM: 12.2(31r)SGA1
Pod Revision 14, Force Revision 31, Tie Revision 32
Telecity_Border_1 uptime is 9 weeks, 4 days, 9 hours, 53 minutes
System returned to ROM by power-on
System image file is "bootflash:cat4500-entservicesk9-mz.122-46.SG.bin"
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
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agree to comply with applicable laws and regulations. If you are unable
to comply with U.S. and local laws, return this product immediately.
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If you require further assistance please contact us by sending email to
cisco WS-C4506 (MPC8540) processor (revision 13) with 524288K bytes of memory.
Processor board ID FOX06460YN3
MPC8540 CPU at 800Mhz, Supervisor V-10GE
Last reset from PowerUp
1 Virtual Ethernet interface
58 Gigabit Ethernet interfaces
2 Ten Gigabit Ethernet interfaces
511K bytes of non-volatile configuration memory.
Configuration register is 0x101
Thanks in advance
03-27-2009 03:30 PM
Hi,
I got it. it was due to a lower AD static route already installed. after removing it. I got it working.
Thanks hritter for your help.
Can some one help me with my second doubt.
03-27-2009 03:46 PM
Your second dounbt? Do you mean question?
03-27-2009 03:47 PM
What all events will trigger our SP's Border Gateway to stop sending the default.
When the BGP router no longer has the 0.0.0.0/0 on its routing table.
__
Edison.
03-27-2009 04:35 PM
Thanks for your time.
Does it mean that my SP BG Router has a Default originate from its upstream as well.
Cheers
Subra
03-27-2009 04:39 PM
Does it mean that my SP has a Default originate from its upstream as well.
Hard to tell what the SP may have but there are several ways on how to inject a 0.0.0.0 into BGP or advertise the 0.0.0.0 to a neighbor for that matter.
The SP may have a dynamic or static default route along with the network 0.0.0.0 under BGP.
The SP may also have a dynamic or static default route along with a distribution information originate under BGP.
or
The SP may have an unconditional default originate on the neighbor statement pointing towards you.
On the latter approach, they don't need to have the 0.0.0.0 in the routing table.
It will advertise the 0.0.0.0 all the time.
HTH,
__
Edison.
03-27-2009 04:48 PM
Thanks again.
I would like to know, if for some reason my SP's BGP peering fails with any other T1 SP or fails to learn the routes from its upstream will it be still sending me a default originate (in case of unconditionally sending default originate). What should i do to overcome this. Please help me clear this doubt.
cheers
Subra
03-27-2009 06:42 PM
Subra,
The best way to know is asking the provider. Each provider will have different BGP policies on how they handle the network advertisement to customers.
If you still want to send your traffic towards the ISP even if they don't send 0.0.0.0/0 network, then you can configure a floating default route towards that same ISP. However, if they aren't sending the 0.0.0.0/0 - you may as well drop it locally.
__
Edison.
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