From: Toh Soon, Lim (tohsoon28@gmail.com)
Date: Thu Aug 16 2007 - 03:10:22 ART
Hi,
AFAIK, the "summary-address" command is able to summarize both internal and
external EIGRP routes that cross that interface. The summarizing router will
source the summary-address as an internal EIGRP route to its neighbors.
There are times when you need to adjust the default AD 5 to a higher value.
E.g. you are doing "ip summary-address eigrp 1 0.0.0.0 0.0.0.0" to
downstream routers. This effectively suppresses all routes and sources a
"default route". If this router also dynamically learns a default route from
upstream router via EIGRP (maybe AD 170), it will be offset by the
summary-address which has AD 5.
Just my two cents.
Thank you.
B.Rgds,
Lim TS
On 8/16/07, Cecil Wilson <Cecil.Wilson@flextronics.com> wrote:
>
> Makes sense,
> thanks
>
>
> Cecil G. Wilson
> IT Network Services
> Office: (901) 215-2710
> Cell: (901) 601-6201
> cecil.wilson@flextronics.com
>
>
> -----Original Message-----
> From: Joseph Brunner [mailto:joe@affirmedsystems.com]
> Sent: Wednesday, August 15, 2007 4:50 PM
> To: Cecil Wilson; 'Narbik Kocharians'; 'Julio Carrasco'
> Cc: ccielab@groupstudy.com
> Subject: RE: Little question about EIGRP summary address
>
> The network statement is often misunderstood for IGP's. I'll help you
> out.
>
> The network statement, (UNLIKE BGP) does not advertise the route into
> the protocol. Rather, it simply matches ip addresses configured on
> interfaces.
> Once those interfaces are matched by the network statement,
> eigrp/ospf/rip, etc. send hellos (in the case of eigrp/ospf) and
> establish adjacencies. In the case of RIP, they send routing updates, as
> rip does not build neighbor adjacencies.
>
> If you put the network statement under BGP, the route is checked in the
> routing table and if it exists, the network IS advertised into BGP
> (providing all other bgp conditions are met).
>
> It's a discrete difference, but one worth noting in your studies. As far
> as what is actually advertised, well that is the mask configured on the
> interface.
>
> -Joe
>
> -----Original Message-----
> From: Cecil Wilson [mailto:Cecil.Wilson@flextronics.com]
> Sent: Wednesday, August 15, 2007 5:41 PM
> To: Joseph Brunner; Narbik Kocharians; Julio Carrasco
> Cc: ccielab@groupstudy.com
> Subject: RE: Little question about EIGRP summary address
>
> Yes but my point was; there are 2 ways advertize route into EIGRP
> or any routing protocol
> 1. network STM under the routing protocol 2. Redistribute into
> routing protocol
>
>
> Cecil G. Wilson
> IT Network Services
> Office: (901) 215-2710
> Cell: (901) 601-6201
> cecil.wilson@flextronics.com
>
>
> -----Original Message-----
> From: Joseph Brunner [mailto:joe@affirmedsystems.com]
> Sent: Wednesday, August 15, 2007 4:23 PM
> To: Cecil Wilson; 'Narbik Kocharians'; 'Julio Carrasco'
> Cc: ccielab@groupstudy.com
> Subject: RE: Little question about EIGRP summary address
>
> Remember my earlier example?
>
> Ip route 10.10.0.0 255.255.255.0 null0254
>
> Router eigrp 1
> Redis static metric 1 1 1 1 1
>
> Int f0/0
> Ip summary-address eigrp 1 10.0.0.0 255.0.0.0 5
>
> Now the eigrp route entered the eigrp topology database via the
> redistribution from static.
>
> Consider this...
>
> Router#Show ip int brief
> R2#sh ip int brief
> Interface IP-Address OK? Method Status
> Protocol
> FastEthernet0/0 173.17.180.3 YES NVRAM up
> up
> FastEthernet0/1 193.1.180.3 YES NVRAM up
> up
>
> Router eigrp 1
> Network 10.10.0.0
>
> Int f0/0
> Ip summary-address eigrp 1 10.0.0.0 255.0.0.0 5
>
> No interface matches the network command, so the eigrp top db does not
> include 10.x.x.x anything, so the summary is not created...
>
> -Joe
>
> -----Original Message-----
> From: Cecil Wilson [mailto:Cecil.Wilson@flextronics.com]
> Sent: Wednesday, August 15, 2007 5:16 PM
> To: Joseph Brunner; Narbik Kocharians; Julio Carrasco
> Cc: ccielab@groupstudy.com
> Subject: RE: Little question about EIGRP summary address
>
> Seems contratictory by your own eg
>
> -redistribution from another protocol, including static -learned from an
> eigrp neighbor -network command matching an up/up interface on the
> router.
>
>
>
>
> Cecil G. Wilson
> IT Network Services
> Office: (901) 215-2710
> Cell: (901) 601-6201
> cecil.wilson@flextronics.com
>
>
> -----Original Message-----
> From: Joseph Brunner [mailto:joe@affirmedsystems.com]
> Sent: Wednesday, August 15, 2007 4:11 PM
> To: Cecil Wilson; 'Narbik Kocharians'; 'Julio Carrasco'
> Cc: ccielab@groupstudy.com
> Subject: RE: Little question about EIGRP summary address
>
> "That is not advertising the routes in eigrp". The "network" command
> determines on which interfaces we run eigrp on. Using the network
> command with a non-existent interface for the purpose of later
> generating a summary does not work.
>
> You can get the constituent routes for creating the summary into eigrp
> via
>
> -redistribution from another protocol, including static -learned from an
> eigrp neighbor -network command matching an up/up interface on the
> router.
>
> -Joe
>
> CCNA
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Cecil Wilson
> Sent: Wednesday, August 15, 2007 3:43 PM
> To: Narbik Kocharians; Julio Carrasco
> Cc: ccielab@groupstudy.com
> Subject: RE: Little question about EIGRP summary address
>
> Do you mean advertisizing those routes in Eigrp?
>
> Eg
>
> Router eigrp 100
>
> Net 10.10.10.1 0.0.0.0
>
> Net 10.10.11.1 0.0.0.0
>
> Net 10.10.12.1 0.0.0.0
>
>
>
> Int e0/0
>
> Summary eigrp 10.10.0.0 0.0.255.255
>
>
>
>
>
> Cecil G. Wilson
>
> IT Network Services
>
> Office: (901) 215-2710
>
> Cell: (901) 601-6201
>
> cecil.wilson@flextronics.com
>
>
>
>
>
> -----Original Message-----
>
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>
> Narbik Kocharians
>
> Sent: Wednesday, August 15, 2007 1:31 PM
>
> To: Julio Carrasco
>
> Cc: ccielab@groupstudy.com
>
> Subject: Re: Little question about EIGRP summary address
>
>
>
> When ever you need to generate a summary route, those routes need to be
>
> advertised in the specific routing protocol before a summary is
>
> generated.
>
>
>
> On 8/15/07, Julio Carrasco <julio.carrasco@ya.com> wrote:
>
> >
>
> > Hello Group,
>
> >
>
> > It4s necessary to configure a component of a summary route under the
>
> > EIGRP proccess to announce the summary address ?, or it is just enough
>
>
>
> > having a component of the sumary route in the routing table ?
>
> >
>
> > i.e.
>
> >
>
> > R1 s0/0-------------------------------- s0/0 R2 .2 -------10.0.0.0/24
>
>
>
> > lan segment
>
> > .1 1.1.1.0/24 network .2
>
> >
>
> > R2 config:
>
> >
>
> > interface s0/0
>
> > ip address 1.1.1.2 255.255.255.0
>
> > ip summary-address eigrp 10 10.0.0.0 255.0.0.0 !
>
> > router eigrp 10
>
> > network 1.1.1.2 0.0.0.0
>
> > network 10.0.0.2 0.0.0.0 --> Do I need to add this to my config if I
>
> > want
>
> > R2
>
> > to announce the summary route ??
>
> > !
>
> >
>
> > Is this enough so R2 announces 10.0.0.0/8 network to R1,
>
> >
>
> > or do I need to configure a component of the 10.0.0.0/8 network unter
>
> > the EIGRP 10 proccess ??
>
> >
>
> > TIA
>
> > Julio
>
> >
>
> > ______________________________________________________________________
>
> > _ Subscription information may be found at:
>
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>
> >
>
>
>
>
>
>
>
> --
>
> Narbik Kocharians
>
> CCIE# 12410 (R&S, SP, Security)
>
> CCSI# 30832
>
> www.Net-WorkBooks.com
>
>
>
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