From: Muhamamd Durrani (dan_schaw@xxxxxxxxx)
Date: Mon Jan 14 2002 - 00:45:59 GMT-3
Hi All,
Luu,
I guess you wanna ask about redistribution scenario
!!!
Inwhich you are redistributing EIGRP routes into OSPF
!!
Well , In this Scenario :
One thing u need to understand is, while
redistributing routes between diffrent protocols the
timers basic (Invalid, holdtime,dead-Interval , hello
Interval etc etc....) doesn't change ...so if eigrp is
redistributing routes into OSPF and that route is no
more valid EIGRP will still use its mechanism for
query and set the route to ACTIVE state and will try
to search it in its topological database first and
than will query to next directly connected neighor and
bla bla .....but OSPF will wait whatever is set for
dead-Interval and will declare route as invalid and
will re-calculate its routing table (spf) ....
Let me know if you need more clarification !!!!
I am just added to the list and have my exam on 27th
march !!!!
Regards,
--- Paul Borghese <pborghese@groupstudy.com> wrote:
> When a route goes down, the router first checks for
> a feasable sucessor. If
> there is no feasable sucessor, it then queries the
> directly connected
> neighbors to see if they have a better route.
>
> What is confusing is the term active. In most
> people vocabulary if you told
> them that the route was active they would say
> "great". "Hey boss, I don't
> know what they are complaining about the route is
> Active". In this case,
> the router is actively looking for a new route :-)
>
>
> Here is a paper by cisco that explains it far better
> then I.
>
> http://www.cisco.com/warp/public/103/eigrp6.html
>
>
> Paul
> ----- Original Message -----
> From: "Huy Luu" <Huy_Luu%COMMONWEALTH@ccginc.com>
> To: "Ellis, Neil" <Neil.Ellis@expanets.com>
> Cc: <ccielab@groupstudy.com>
> Sent: Friday, January 11, 2002 2:51 PM
> Subject: RE: EIGRP routes
>
>
> > Thankyou Neil
> >
> > I'm not sure if this info is correct, can you
> please verify
> >
> > For Eigrp, when a neighbor is unreachable after
> the hold time which is
> > three times the hello, the route is actually mark
> active and remain so for
> > a default of three minutes while DUAL finds an
> alternative route. So the
> > process takes 3-4 minutes before the route is
> consider unreachable but
> > still advertised as unreachable route to other
> live EIGRP neighbor.
> >
> > If you run OSPF and EIGRP and once the route is
> unavailable through EIGRP,
> > how much time does it take for OSPF to take over
> and add an OSPF route to
> > the routing table?
> >
> > Please confirm.
> >
> >
> >
> >
> > "Ellis, Neil"
> > <Neil.Ellis@exp To:
> 'Huy Luu'
> <Huy_Luu%COMMONWEALTH@ccginc.com>,
> > anets.com>
> ccielab@groupstudy.com
> > cc:
> "Duffy, Bryan"
> <Bryan.Duffy@expanets.com>
> > 01/11/02 01:50 Subject:
> RE: EIGRP routes
> > PM
> >
> >
> >
> >
> >
> >
> >
> > LUU:
> >
> >
> >
> > It depends on the routing protocol in use. OSPF
> uses a hello and dead
> > interval. The hello depending upon the network
> type is default at 10
> > seconds. The dead interval is always 4 times the
> hello interval. If a
> > neighbor is not heard from by the time the dead
> interval is expired it is
> > assumed down and taken out of the neighbor table.
> The hello interval can
> be
> > manually manipulate with the interface command ip
> ospf hello-interval.
> >
>
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/ip_r
> >
> > /iprprt2/1rdospf.htm#xtocid796920
> >
> >
> > At the time that the dead interval expires that
> router is no longer a
> > neighbor and that whole routing table is taken
> out. The SPF tree also has
> > to
> > be recalculated. Good resources are Jeff Doyle
> TCP/IP Volume I and a new
> > Cisco press book CCIE Practical Studies. Must
> reads for anyone attempting
> > the CCIE Lab!
> >
> >
> > With Eigrp neighbors are communicated with in a
> similar manner. Hellos are
> > multicast out every 5 seconds or 60 seconds
> depending on the network type.
> > It can be manipulated with the interface command
> ip hello-interval eigrp.
> >
>
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/ip_r
> >
> > /iprprt2/1rdeigrp.htm#xtocid1895711
> > The hello will include a hold time which is three
> times the hello timer.
> > This determines how long to wait for another hello
> from the sending
> > neighbor. Once that timer has expired the neighbor
> is considered gone. The
> > default for hold time can be manipulated with the
> interface command ip
> > hold-time eigrp.
> >
>
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/ip_r
> >
> > /iprprt2/1rdeigrp.htm#xtocid1895712
> > As with OSPF once the neighbor adjacency is lost
> all routes from that
> > neighbor is cleared from the routing table.
> >
> >
> > RIP has an expiration timer or timeout for routes
> in the routing table.
> > Cisco may refer to it as an invalid timer. This is
> set at a default of 180
> > seconds or 6 update periods. The protocol will
> change a route's hop count
> > to
> > 16 or unreachable if it has not been given an
> update for that particular
> > route. Updates in the Cisco world can vary
> (according to Jeff Doyle's
> > TCP/IP
> > Volume I) between 25.5 to 30 seconds. Now there's
> another timer called the
> > flush timer that is set to 240 seconds. The route
> is advertised as
> > unreachable until that timer expires. At that time
> the route is finally
> > removed from the router. The last timer is
> referred to as the holddown
> > timer. Is is used when an update is received with
> a hop count greater than
> > what exists in the current routing table. The
> protocol will place this
> > route
> > into holddown for 180 seconds.
> >
> >
> > I hope all of this helps it is available in TCP/IP
> Volume I by Jeff Doyle.
> > Good luck to all!
> >
> >
> > Best Regards,
> >
> > Neil Ellis MCSE, CCNP,CCDP,A+,Net+,i-Net+,
> > Network Engineer
> > Converged Solutions
> > * Neil.Ellis@expanets.com
> > * 303-300-6320 x6224
> > Cell 303-548-9453
> >
> >
> >
> > -----Original Message-----
> > From: Huy Luu
> [mailto:Huy_Luu%COMMONWEALTH@ccginc.com]
> > Sent: Friday, January 11, 2002 11:08 AM
> > To: ccielab@groupstudy.com
> > Subject: EIGRP routes
> >
> >
> > When Eigrp, OSPF, RIP or any routing protocol
> looses a neighbor and does
> > not have alternative route to networks advertised
> by the down neighbor,
> > how long does it take for that neighbor's routes
> to dissapear from the
> > routing table? Is there a default timeout value
> for routes in the
> > routing table?Any link from CCO will be greatly
> appreciated. Thanks all
>
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