From: Tyson Scott (tscott@ipexpert.com)
Date: Tue Mar 17 2009 - 10:45:07 ART
Nadeem,
That is correct. All BGP tables are scanned. You can verify this by
turning on "debug ip bgp events" You will see the scan occur during each
interval. Here is some sample output.
R1(config-router)#do debug ip bgp events
BGP events debugging is on
R1(config-router)#
BGP(4): Import timer expired. Walking from 1 to 1
BGP(5): Import timer expired. Walking from 1 to 1
BGP(4): Import timer expired. Walking from 1 to 1
BGP(5): Import timer expired. Walking from 1 to 1
R1(config-router)#
BGP(4): Import timer expired. Walking from 1 to 1
BGP(5): Import timer expired. Walking from 1 to 1
R1(config-router)#
BGP: Performing BGP general scanning
BGP(0): scanning IPv4 Unicast routing tables
BGP(IPv4 Unicast): Performing BGP Nexthop scanning for general scan
BGP(0): Future scanner version: 5476, current scanner version: 5475
BGP(1): scanning IPv6 Unicast routing tables
BGP(IPv6 Unicast): Performing BGP Nexthop scanning for general scan
BGP(1): Future scanner version: 5476, current scanner version: 5475
BGP(3): scanning IPv4 MDT routing tables
BGP(IPv4 MDT): Performing BGP Nexthop scanning for general scan
BGP(3): Future scanner version: 5476, current scanner version: 5475
BGP(4): scanning VPNv4 Unicast routing tables
BGP(VPNv4 Unicast): Performing BGP Nexthop scanning for general scan
BGP(4): Future scanner version: 5476, current scanner version: 5475
BGP(5): scanning VPNv6 Unicast routing tables
BGP(VPNv6 Unicast): Performing BGP Nexthop scanning for general scan
BGP(5): Future scanner version: 5476, current scanner version: 5475
BGP(6): scanning IPv4 Multicast routing tables
BGP(IPv4 Multicast): Performing BGP Nexthop scanning for general scan
BGP(6): Future scanner version: 5476, current scanner version: 5475
BGP(7): scanning IPv6 Multicast routing tables
BGP(IPv6 Multicast): Performing BGP Nexthop scanning for general scan
BGP(7): Future scanner version: 5476, current scanner version: 5475
BGP(8): scanning NSAP Unicast routing tables
BGP(NSAP Unicast): Performing BGP Nexthop scanning for general scan
BGP(8): Future scanner version: 5476, current scanner version: 5475
Regards,
Tyson Scott - CCIE #13513 R&S and Security
Technical Instructor - IPexpert, Inc.
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-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Nadeem Ansari
Sent: Tuesday, March 17, 2009 3:38 AM
To: Narbik Kocharians
Cc: naveen M S; M Lab; joe_astorino@comcast.net; CCIE R/S, Groupstudy; CCIE,
R/S OSL
Subject: Re: "bgp scan-time" command documentation
Hi Narbik,
As per my understanding BGP scan timer checks the next-hop reachibility for
BGP table by looking in to the routing table, and it checks for all address
family including IPv4 Unicast, IPv6 Unicast, VPNv4, etc.
correct me if I am wrong
Regards
Nadeem
On Tue, Mar 17, 2009 at 9:35 AM, Narbik Kocharians <narbikk@gmail.com>wrote:
> BGP scan-time takes care of conditional advertisement, Route Dampening and
> every 60 seconds (The default) it scans the entire BGP table and ensure
> that
> the next hop is reachable.
>
> On Mon, Mar 16, 2009 at 4:35 PM, naveen M S <navin.ms@gmail.com> wrote:
>
> > Looking at the master index, it is clear that ..
> >
> > 1) bgp scan-time .. is used for vpnv4 unicast routes
> > 2) bgp nexthop trigger delay .. is used for unicast, mcast, vpnv4 etc
> > routes.
> >
> > For Joe's task, "bgp nexthop trigger delay .." should be the right
> answer.
> >
> >
> >
> > On Mon, Mar 16, 2009 at 3:17 PM, M Lab <mlabccie@gmail.com> wrote:
> >
> > > I did find this in the Master Index....
> > >
> > >
> http://www.cisco.com/en/US/docs/ios/mcl/124mainlinemcl/124_01.html#LTR_B
> > >
> > > Which pointed me to mpls of all places...
> > >
> > >
> > >
> >
>
http://www.cisco.com/en/US/docs/ios/mpls/command/reference/mp_a1.html#wp1011
737
> > >
> > > I'm sure there is a logical reason, but I don't know what it is. ;-)
> > >
> > > On Mon, Mar 16, 2009 at 2:37 PM, <joe_astorino@comcast.net> wrote:
> > >
> > > > Anybody know where to find the documentation on this? I do not see
it
> > > > listed in the IOS 12.4 mainline command reference under BGP. Also,
> can
> > > > anybody help differentiate the difference between the scan-time
> command
> > > and
> > > > the "bgp nexthop" command?
> > > >
> > > > I have a task that asks me "After every 15 seconds the router will
> > check
> > > to
> > > > see weather next-hops of installed prefixes are reachable" Since
"bgp
> > > > scan-time" was not in the documentation, I thought an acceptable
> answer
> > > > would have been "bgp nexthop" as documented in the 12.4 command
> > reference
> > > > and shown below. However, the solution calls for "bgp scan-time 15"
> Has
> > > bgp
> > > > nexthop replaced bgp scan-time ????
> > > > I'm a bit confused.
> > > >
> > > >
> > > >
> > >
> >
>
http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_bgp1.html
> > > >
> > > > BGP next-hop address tracking is event driven. BGP prefixes are
> > > > automatically tracked as peering sessions are established. Next-hop
> > > changes
> > > > are rapidly reported to BGP as they are updated in the routing
> > > information
> > > > base (RIB). This optimization improves overall BGP convergence by
> > > reducing
> > > > the response time to next-hop changes for routes installed in the
> RIB.
> > > When
> > > > a best-path calculation is run in between BGP scanner cycles, only
> the
> > > > changes are processed and tracked.
> > > >
> > > >
> > > > Blogs and organic groups at http://www.ccie.net
> > > >
> > > >
> _______________________________________________________________________
> > > > Subscription information may be found at:
> > > > http://www.groupstudy.com/list/CCIELab.html
> > >
> > >
> > > Blogs and organic groups at http://www.ccie.net
> > >
> > >
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