[c-nsp] BGP as-path access list question on 1841 routers

[Kenny Sallee]

You don't need to specify the 'soft-reconfiguration' under the bgp neighbor
but I believe you still should do a

clear ip bgp nei <ip> soft in|out

or

clear ip bgp nei <ASN> soft in|out

Kenny

On Thu, Apr 1, 2010 at 11:45 AM, Dan Goldberg <dan.goldberg at vgt.net> wrote:

>
> I left out a detail that may be important:
> This is on an MPLS WAN where I control all the CEs. The PEs are all
> provider controlled.
> The "hubs" I mentioned are just larger CEs with a broader BGP policy
> permitting all my AS numbers. So each routers neighbor is not under my
> control.
>
> Thanks again.
> Dan
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net [mailto:
> cisco-nsp-bounces at puck.nether.net] On Behalf Of Dan Goldberg
> Sent: Thursday, April 01, 2010 1:10 PM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] BGP as-path access list question on 1841 routers
>
> Hi there,
> I have what is probably a very simple BGP question which I wanted to ask.
> The short version is how to refresh/reread an existing BGP as-path
> access-list (with new permits added) without rebooting the router?
>
> The long version:
> I run primarily IOS Version 12.4(15)T9 on 1841s with EBGP configured
> largely as follows. I have roughly 100 sites like this. For the most part
> all sites have connectivity to 2 "hubs", a NOC and an alternative (BCP) NOC.
> Tail sites are not supposed to be able to reach each other or even know
> about each other (through BGP) in most cases. That is what the as-path
> access list provides.
>
> There are some cases where there are groups of ASes that I want to allow
> BGP to learn about each other. These relationships are built sometimes
> arbitrarily.
>
> <all numbers are faked>
> router bgp 65534
> network blah mask 255.255.255.255
> neighbor www.xxx.yyy.zzz remote-as 65533
>  neighbor www.xxx.yyy.zzz filter-list 1 in
> !
> ip as-path access-list 1 permit 64542
> ip as-path access-list 1 permit 64543
>
> I have found that if I start with the above as-path filter and then add a
> new permit to the filter as below:
> ip as-path access-list 1 permit 64551
>
> #sho ip bgp neighbors shows:
> Neighbor capabilities:
>    Route refresh: advertised and received(old & new)
>
> The question (finally):
> Can I use a soft restart to re-read the as-path access-list?
> Do I need to add a "neighbor soft-reconfiguration" statement to BGP first?
> Is there another method to force a reread of the filter-list without losing
> connectivity to the router?
>
> Thanks I appreciate your feedback.
>
> --
> Dan Goldberg
> <title removed due to other thread>
> Video Gaming Technologies, Inc.
> 434-992-5450
>
>
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