From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Mon Nov 24 2003 - 16:37:48 GMT-3
Kurt,
Correct, if route-refresh is supported you can 'clear ip bgp
x.x.x.x in' without memory implications. Route-refresh is supported by
default as of 12.0T.
> also memory held by a previous soft (configured) reset will
> be held until a reboot ??
This I'm not sure about, but I'm going to guess no. If you add
or remove the 'soft-reconfiguration inbound' statement a hard clear of
the BGP neighbor automatically takes place. Therefore any cached
received routes will be automatically flushed.
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 708-362-1418 (Outside the US and Canada)
> -----Original Message-----
> From: kurt [mailto:kurt@cybernex.net]
> Sent: Monday, November 24, 2003 1:18 PM
> To: Brian McGahan
> Subject: Re: BGP Soft Reset (BGP RIB)
>
>
>
> ok ,
>
> if i understand this correctly
> i had been in the practice of setting
> neighbor xxxxx soft-reconfiguration inbound
> this causes the memory doubling issue
> correct?
>
> if i do a
> sh ip bgp neighbor
> and it says route refresh is supported then i can
> do a clear ip bgp * soft without memory implications
> right ??
>
> also memory held by a previous soft (configured) reset will
> be held until a reboot ??
>
> main-gw#sbn
> BGP neighbor is , remote, external link
> BGP version 4, remote router ID BGP state = Established,
> up for 7w4d
> Last read 00:00:00, hold time is 180, keepalive interval is
> 60 seconds
> Neighbor capabilities:
> Route refresh: advertised and received(old & new)
> Address family IPv4 Unicast: advertised and received
> Message statistics:
> InQ depth is 7
> OutQ depth is 0
> Sent Rcvd
> Opens: 2 2
> Notifications: 1 0
> Updates: 6 3448866
> Keepalives: 148547 148540
> Route Refresh: 1 0
> Total: 148557 3597408
> Default minimum time between advertisement runs is 30 seconds
>
> For address family: IPv4 Unicast
> BGP table version 10566014, neighbor version 0
> Index 1, Offset 0, Mask 0x2
> Inbound path policy configured
> Outgoing update prefix filter list is locally-originated
>
>
> ----- Original Message -----
> From: "Brian McGahan" <bmcgahan@internetworkexpert.com>
> To: "'Kurt Kruegel'" <kurt@cybernex.net>;
> <Ken.Farrington@barclayscapital.com>; <ccielab@groupstudy.com>
> Sent: Monday, November 24, 2003 1:50 PM
> Subject: RE: BGP Soft Reset (BGP RIB)
>
>
> > Kurt,
> >
> > If route-refresh is supported then both 'clear ip bgp * in'
> and 'clear
> > ip bgp * soft in' will do route-refresh. If route-refresh is not
> > supported and soft-reconfiguration is not configured you
> will get the
> > following error message:
> >
> > router#clear ip bgp 172.16.4.3 in
> > %BGP: Inbound soft reconfig for 172.16.4.3 not possible as it
> > has neither refresh capability, nor inbound soft reconfig
> >
> > router#clear ip bgp 172.16.4.3 soft in
> > %BGP: Inbound soft reconfig for 172.16.4.3 not possible as it
> > has neither refresh capability, nor inbound soft reconfig
> >
> >
> >
> > HTH,
> >
> > Brian McGahan, CCIE #8593
> > bmcgahan@internetworkexpert.com
> >
> > Internetwork Expert, Inc.
> > http://www.InternetworkExpert.com
> > Toll Free: 877-224-8987
> > Direct: 708-362-1418 (Outside the US and Canada)
> >
> >
> >
> > > -----Original Message-----
> > > From: Kurt Kruegel [mailto:kurt@cybernex.net]
> > > Sent: Sunday, November 23, 2003 7:45 PM
> > > To: Brian McGahan; Ken.Farrington@barclayscapital.com;
> > > ccielab@groupstudy.com
> > > Subject: Re: BGP Soft Reset (BGP RIB)
> > >
> > >
> > > so ....
> > > will
> > > clear ip bgp in
> > > force a route refresh ???
> > >
> > >
> > >
> > > ----- Original Message -----
> > > From: "Brian McGahan" <bmcgahan@internetworkexpert.com>
> > > To: <Ken.Farrington@barclayscapital.com>; <ccielab@groupstudy.com>
> > > Sent: Sunday, November 23, 2003 8:21 PM
> > > Subject: RE: BGP Soft Reset (BGP RIB)
> > >
> > >
> > > > Ken,
> > > >
> > > > "Soft-reconfiguration" is Cisco's old proprietary way
> of allowing
> > > > changes in the BGP policy without tearing down the TCP
> session and
> > > > rebuilding it. "Route-refresh" is the standard and
> > > preferred method
> > > > to do so.
> > > >
> > > > Soft-reconfiguration must be preconfigured with the
> > > 'neighbor x.x.x.x
> > > > soft-reconfiguration inbound' bgp subcommand. With
> > > soft-reconfig, the
> > > > router caches prefixes received from a neighbor, then
> installs a
> > > > separate copy which is a result of configured inbound filters.
> > > > The original copy can be seen by issuing the 'show ip bgp nei
> > > > x.x.x.x received-routes' command. Using this method is not
> > > > recommended, because the memory required on a per
> neighbor basis
> > > > can be
> > > effectively
> > > > doubled.
> > > >
> > > > Unlike soft-reconfig, route-refresh does not need to keep
> > > two copies
> > > > of the BGP table. There is no way to see the
> unmodified received
> > > > table other than going to the upstream side and doing a 'sh
> > > ip bgp nei
> > > > x.x.x.x advertised'. Route-refresh is part of the BGP
> > > > capabilities exchange, and does not require any additional
> > > > configuration.
> > > >
> > > >
> > > > HTH,
> > > >
> > > > Brian McGahan, CCIE #8593
> > > > bmcgahan@internetworkexpert.com
> > > >
> > > > Internetwork Expert, Inc. http://www.InternetworkExpert.com
> > > > Toll Free: 877-224-8987
> > > > Direct: 708-362-1418 (Outside the US and Canada)
> > > >
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> > > > > Behalf Of Bob Sinclair
> > > > > Sent: Sunday, November 23, 2003 5:05 PM
> > > > > To: Ken.Farrington@barclayscapital.com; ccielab@groupstudy.com
> > > > > Subject: Re: BGP Soft Reset (BGP RIB)
> > > > >
> > > > >
> > > > > Ken,
> > > > >
> > > > > The soft-reconfiguration inbound command is required if you
> > > > > want to issue a
> > > > > "neighbor received-routes" command. The received routes
> > > > > command will show
> > > > > you what the neighbor is sending you BEFORE any inbound
> > > > > policies are applied. Very helpful!
> > > > >
> > > > > HTH,
> > > > >
> > > > > -Bob Sinclair
> > > > > CCIE #10427, CISSP, MCSE
> > > > > bsinclair@netmasterclass.net
> > > > >
> > > > > ----- Original Message -----
> > > > > From: <Ken.Farrington@barclayscapital.com>
> > > > > To: <ccielab@groupstudy.com>
> > > > > Sent: Sunday, November 23, 2003 5:05 PM
> > > > > Subject: BGP Soft Reset (BGP RIB)
> > > > >
> > > > >
> > > > > > Guys,
> > > > > >
> > > > > > Please can I confirm that nowadays you do not have
> to use the "
> > > > > > neighbor 200.200.1.1 soft-reconfiguration inbound" command.
> > > > > >
> > > > > > All my routers without this command have the route-refresh
> > > > > capability
> > > > > > on (please see output below), and as such and I can do a
> > > > > >
> > > > > > "cle ip bgp 200.200.1.1 soft in" or "cle ip bgp
> > > > > 200.200.1.1 in"
> > > > > >
> > > > > > without configuring soft-reconfiguration under the
> BGP process.
> > > > > >
> > > > > >
> > > > > > Also, I assume the router stores two copies of the
> RIB, one
> > > > > > unmodified
> > > > > and
> > > > > > one modified with inbound policies. If this is
> > > correct, is there
> > > > > > a
> > > > > > way of showing the unmodified RIB ?
> > > > > >
> > > > > >
> > > > > > TEST2#sh ip bgp nei 200.200.1.1
> > > > > > BGP neighbor is 200.200.1.1, remote AS 6500, external link
> > > > > > BGP version 4, remote router ID 155.195.16.161
> > > > > > BGP state = Established, up for 00:06:48
> > > > > > Last read 00:00:48, hold time is 180, keepalive interval
> > > > > is 60 seconds
> > > > > > Neighbor capabilities:
> > > > > > Route refresh: advertised and received(new)
> > > > > > <======================Please Note
> > > > > > Address family IPv4 Unicast: advertised and received
> > > > > > Received 1481 messages, 936 notifications, 0 in queue
> > > > > > Sent 1537 messages, 0 notifications, 0 in queue
> > > > > > Route refresh request: received 0, sent 6
> > > > > > Default minimum time between advertisement runs
> is 30 seconds
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > >
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