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RE: bgp soft-reconfig in? posted 10/23/2002
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Route Refresh Capability for BGP-4

http://www.faqs.org/rfcs/rfc2918.html

Brian Dennis, CCIE #2210 (R&S/ISP Dial)

-----Original Message-----
From: nobody@xxxxxxxxxxxxxx [mailto:nobody@xxxxxxxxxxxxxx] On Behalf Of
MADMAN
Sent: Wednesday, October 23, 2002 12:52 PM
To: Brian McGahan
Cc: Liban.Mohamed@xxxxxxxxxxxxxxx; ccielab@xxxxxxxxxxxxxx;
rich@xxxxxxxxxxxxxx
Subject: Re: bgp soft-reconfig in?

  I take it the route-refresh is the new, (12.1) dynamic inbound soft
reset which requires no new config.  (I was checking out the URL you
provided:)  So I set up a very basic BGP connection to see if this was
negociated, both routers are running 12.2xx but I'm not sure what this
output is saying and can't find it on CCO:

C7206VXRB#sh ip bgp nei
BGP neighbor is 172.28.64.11,  remote AS 10, external link
  BGP version 4, remote router ID 172.28.64.11
  BGP state = Established, up for 00:00:13
  Last read 00:00:12, hold time is 180, keepalive interval is 60 seconds
  Neighbor capabilities:
    Route refresh: advertised and received(old & new)

  What is the "Route refresh: advertised and received(old & new)"?  I
assume the routers have negociated that they are capable of dynamic
reset, what is the old and new??

  Thanks

  Dave


Brian McGahan wrote:
> 
>         Soft-reconfig and route-refresh are two different
technologies.
> They both accomplish pretty much the same thing, however they are
> implemented differently.
> 
>
http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_configur
> ation_guide_chapter09186a00800d97fc.html#xtocid9
> 
>         Route-refresh is preferable over soft-reconfig, since there is
> no additional configuration required, and it does not require any
> additional memory resources.  Soft-reconfig inbound can be dangerous
to
> use on a production BGP router, since inbound updates must be first
> cached, attributes applied, then flushed from memory.  This means that
> if your router is short on memory, it could crash.
> 
>         For those of you with access to the Partner E-Learning
> connection, check out this link on multiprotocol extensions for BGP.
It
> gives a good overview of route-refresh and ORF.
> 
> http://cisco.partnerelearning.com/pec/trnevtdtl.asp?EvtID=39137
> 
> HTH
> 
> Brian McGahan, CCIE #8593
> Director of Design and Implementation
> brian@xxxxxxxxxxxxxxx
> 
> CyscoExpert Corporation
> Internetwork Consulting & Training
> Voice: 847.674.3392
> Fax: 847.674.2625
> 
> > -----Original Message-----
> > From: nobody@xxxxxxxxxxxxxx [mailto:nobody@xxxxxxxxxxxxxx] On Behalf
> Of
> > Liban.Mohamed@xxxxxxxxxxxxxxx
> > Sent: Sunday, October 20, 2002 2:47 PM
> > To: ccielab@xxxxxxxxxxxxxx; rich@xxxxxxxxxxxxxx
> > Subject: RE: bgp soft-reconfig in?
> >
> > The dynamic inbound soft reset capability was added to
> > Cisco's BGP support in Cisco IOS Software Release
> > 12.0(6)T. BGP Soft Reset Enhancement is supported on
> > most Cisco router platforms up through the Cisco 7500
> > Series routers. Soft resets can be initiated without extra
> > commands using only the clear ip bgp in command.
> >
> >
> > Basically soft reconfiguration is to gracefully allow policies to be
> > configured and activated without "hardsetting" the bgp session.
There
> > are
> > two kinds. Outbound and inbound. For inbound, all recieved routes
are
> > stored
> > regardless of the fact whether they are accepted or denied. When we
> > clear
> > bgp with soft in, the polices are applied on the stored received
path.
> > When we do clear bgp soft out, all entries in bgp table are re-run
and
> > new
> > updates are generated to be sent out.
> > syntax:
> > 1. sh ip bgp neighbor <peer address> received-routes
> > This displays all the received updates from neighbor
> > 2. neighbor <address> soft-reconfiguration <in>
> > This will start storing the received updates. So required for
INBOUND
> > soft
> > reconfig. Outbound reconfig does not need anything to be configured.
> >
> >
> >
> >
> > Thanks,
> >
> >
> > Liban Mohamed
> > IP Engineer
> > Sprintlink Internet BackBone
> > www.sprint.net
> >
> > -----Original Message-----
> > From: rich [mailto:rich@xxxxxxxxxxxxxx]
> > Sent: Sunday, October 20, 2002 2:56 PM
> > To: ccielab
> > Cc: rich
> > Subject: bgp soft-reconfig in?
> >
> >
> > Is it true, when the neighbors support;
> >
> > Neighbor capabilities: (taken from sho ip bgp neighbor)
> >     Route refresh: advertised and received
> >     Address family IPv4 Unicast: advertised and received
> >
> > that you don't need to use the neighbor x.x.x.x soft-reconfiguration
> > inbound command?  I have not used this command once.  After making a
> > change to my bgp I just do a clear ip bgp XX sof.
> >
> >
> > Rich

-- 
David Madland
CCIE# 2016
Sr. Network Engineer
Qwest Communications
612-664-3367

"You don't make the poor richer by making the rich poorer." --Winston
Churchill