From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Fri Mar 16 2007 - 00:27:31 ART
router1#sh ip bgp 192.168.117.249
BGP routing table entry for 192.168.117.249/32, version 0
Paths: (4 available, no best path) <-----
"no best path" means that the prefix is not candidate for installation in the BGP table and henceforth is not candidate to be advertised to any BGP neighbor. Check the BGP Bestpath Selection documentation to see why the route is not being installed as best. The most common reasons are that either synchronization is on and the synchronization rule is not met or you do not have an IGP route to the next hop value. For more info: http://www.cisco.com/warp/public/459/25.shtml
HTH,
Brian McGahan, CCIE #8593 (R&S/SP)
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987 x 705
Outside US: 775-826-4344 x 705
24/7 Support: http://forum.internetworkexpert.com
Live Chat: http://www.internetworkexpert.com/chat/
________________________________________
From: Au, Ricky [CCC-OT_IT] [mailto:ricky.au@citigroup.com]
Sent: Thursday, March 15, 2007 9:09 PM
To: Anthony Bonilla
Cc: Brian McGahan; Ming Ki Au
Subject: RE: route advertise in BGP
Dear,
The next hop IP address is directly connected... please see the following.
router1#sh ip bgp 192.168.117.249
BGP routing table entry for 192.168.117.249/32, version 0
Paths: (4 available, no best path)
Multipath: eBGP
Not advertised to any peer
2908 65445 65016, (received-only)
199.67.157.66 from 199.67.157.66 (192.168.116.252)
Origin IGP, localpref 100, valid, external
65445 65016, (received-only)
199.67.152.53 from 199.67.152.53 (199.67.154.2)
Origin IGP, localpref 100, valid, external
2908 65445 65016, (received-only)
199.67.157.70 from 199.67.157.70 (192.168.116.20)
Origin IGP, localpref 100, valid, external
65445 65016, (received-only)
199.67.152.49 from 199.67.152.49 (199.67.154.1)
Origin IGP, localpref 100, valid, external
router1#sh ip ro
router1#sh ip route 199.67.157.66
Routing entry for 199.67.157.64/30
Known via "connected", distance 0, metric 0 (connected, via interface)
Routing Descriptor Blocks:
* directly connected, via GigabitEthernet1/7
Route metric is 0, traffic share count is 1
router1#sh ip roue
router1#sh ip rout
router1#sh ip route 199.67.152.53
Routing entry for 199.67.152.52/30
Known via "connected", distance 0, metric 0 (connected, via interface)
Routing Descriptor Blocks:
* directly connected, via GigabitEthernet1/6
Route metric is 0, traffic share count is 1
router1#sh ip ro
router1#sh ip route 199.67.157.70
Routing entry for 199.67.157.68/30
Known via "connected", distance 0, metric 0 (connected, via interface)
Routing Descriptor Blocks:
* directly connected, via GigabitEthernet1/8
Route metric is 0, traffic share count is 1
router1#sh ip to
router1#sh ip ro
router1#sh ip route 199.67.152.49
Routing entry for 199.67.152.48/30
Known via "connected", distance 0, metric 0 (connected, via interface)
Routing Descriptor Blocks:
* directly connected, via GigabitEthernet1/5
Route metric is 0, traffic share count is 1
router1#
Regards,
Ricky Au
Network Engineering
Citigroup Architecture & Technology Engineering (CATE)
Address: Citigroup Global Markets Asia Pacific 15/F, 3 Exchange Square Central, Hong Kong, China
Email: ricky.au@citigroup.com
Office: +852-3551-5542
Fax: +852-3551-5182
________________________________________
From: Anthony Bonilla [mailto:anthonybonilla.ccie@gmail.com]
Sent: Friday, March 16, 2007 10:35 AM
To: Au, Ricky [CCC-OT_IT]
Cc: Brian McGahan; Ming Ki Au; Cisco certification
Subject: Re: route advertise in BGP
Ricky,
Would it be possible for you to share your routing table and configs with us? First thing I would like to confirm is that if you have a valid route to your next hop IP address within AS200 for the router(s) advertising host routes from AS100 - can you confirm that? Secondly, how are you advertising /23 network to AS300 - do you have a static route or something because just by using a network statement should not aggregate host routes to a /23 network?
HTH,
Tony
On 3/15/07, Au, Ricky [CCC-OT_IT] <ricky.au@citigroup.com> wrote:
Dear all,
It is happened in a real case. I show ip bgp for the host route /32. It says that there are 4 available paths but no best path. Why?
Paths: (4 available, no best path)
Multipath: eBGP
Not advertised to any peer
Regards,
Ricky Au
Network Engineering
Citigroup Architecture & Technology Engineering (CATE)
Address: Citigroup Global Markets Asia Pacific 15/F, 3 Exchange Square Central, Hong Kong, China
Email: ricky.au@citigroup.com
Office: +852-3551-5542
Fax: +852-3551-5182
________________________________________
From: Anthony Bonilla [mailto:anthonybonilla.ccie@gmail.com]
Sent: Friday, March 16, 2007 4:36 AM
To: Brian McGahan
Cc: Ming Ki Au; Cisco certification; Au, Ricky [CCC-OT_IT]
Subject: Re: route advertise in BGP
Brian,
To me, it sounded like a concept type question - it did not seem to be that Ming has a real setup that he is working with. I would say you would advertise both host routes and /23 out to your eBGP peer if the routes are valid and also you need to ensure that there is a corresponding /23 network in your IGP before you can advertise it via BGP using a network statement being that the router will not summarize the two host routes automatically.
HTH
Tony
On 3/15/07, Brian McGahan <bmcgahan@internetworkexpert.com > wrote:
Assuming the host routes aren't being manually filtered they should be
passed on. Look at the "show ip bgp 192.168.10.91 255.255.255.255"
output and see what it says about it being advertised. Also are you
sure that these host routes are best routes?
HTH,
Brian McGahan, CCIE #8593 (R&S/SP)
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987 x 705
Outside US: 775-826-4344 x 705
24/7 Support: http://forum.internetworkexpert.com
Live Chat: http://www.internetworkexpert.com/chat/
-----Original Message-----
From: nobody@groupstudy.com [mailto: nobody@groupstudy.com] On Behalf Of
Ming Ki Au
Sent: Thursday, March 15, 2007 11:22 AM
To: Cisco certification
Cc: ricky.au@citigroup.com
Subject: route advertise in BGP
Dear all,
I have a question on BGP, can anyone help?
A router running BGP AS 200 is receiving from its ebgp peers (AS 100)
with 2
host routes. 192.168.10.91/32 and 192.168.10.92/32.
Then it advertise another route using the network command with the
followings.
router bgp 200
network 192.168.10.0 mask 255.255.254.0
What routes will be distributed to another eBGP peer (AS 300)? I found
that
only a single route 192.168.10.0/23 which is originated from AS 200 is
advertised to AS 300, is it correct?
This archive was generated by hypermail 2.1.4 : Sun Apr 01 2007 - 06:35:51 ART