From: Tarun Pahuja (pahujat@gmail.com)
Date: Mon Jun 18 2007 - 15:06:30 ART
Ben,
My comments were based on the following document and I was
referring to standard ACLs.
http://www.cisco.com/warp/public/103/eigrpfaq.shtml
"The use of ACL and distribute-list under EIGRP does not work in this case.
This is because ACLs do not check the mask, they just check the network
portion. Since the network portion is the same, when you allow 172.16.1.0/24,
you also allow 172.16.1.0/28."
I usually use Prefix-list for route filtering as it gives me more control. I
have seen cases where extended ACLs are used to match subnet mask, but the
logic is slightly different as you suggested. Destination portion becomes
the subnet mask portion. You will find prefix list must easier to implement
specially when dealing with VLSM addresses.
HTH,
Tarun
On 6/18/07, Ben <bmunyao@gmail.com> wrote:
>
> Tarun
>
> "remember ACLs will not match subnet mask."
>
>
> Correct me if I'm off track but I was under the impression an ACL can also
> match a subnet mask as follow:
>
> access-list 100 permit ip host 150.4.5.0 host 255.255.255.0
>
> I haven't tested it in a lab yet, so I'm still unsure if it works. I'd
> sure appreciate any input on this ACL usage.
>
> Ben
>
>
>
>
> On 6/18/07, Tarun Pahuja <pahujat@gmail.com> wrote:
>
> > Yan,
> > You are right about the use to route-map for advanced filtering.
> > I
> > am not aware of any limitations of distributing routes in and out of
> > eigrp
> > in terms of routing protocols. Remember, to specify the metric when
> > redistributing in eigrp as their is no default metric, also use
> > prefix-list
> > in place of ACLs for better control, remember ACLs will not match subnet
> > mask.
> >
> > For your second question, It is more useful in many cases to configure
> > the
> > route map that includes matching the route type based on the source
> > protocol
> > and AS using the distribute-list command for EIGRP.
> >
> > In the following example, the source protocol is specified as Border
> > Gateway
> > Protocol (BGP) and the AS number is 2, which permits external EIGRP
> > routes
> > of BGP:
> >
> > match source-protocol bgp 2
> >
> > HTH,
> > Tarun
> >
> >
> > On 6/17/07, Filyurin, Yan <yan.filyurin@eds.com> wrote:
> > >
> > > Hello Groupstudy. Recently I've reading up EIGRP support for route
> > maps
> > > and the way they explain it is that it almost works like a distribute
> > > list where you can do advanced matching on incoming routes. However
> > > according to some playing around and documentation, use of route-map
> > in
> > > a distribute list is only supported with OSPF. So here I was reading
> > > this URL:
> > >
> > >
> > http://www.cisco.com/en/US/products/sw/iosswrel/ps5207/products_feature_
> > > guide09186a0080220721.html
> > >
> > > And the part that confused me the most was this
> > >
> > > "
> > > The EIGRP Route Map Support feature enables Enhanced Interior Gateway
> > > Routing Protocol (EIGRP) to interoperate with other protocols by
> > > filtering inbound and outbound traffic based on complex route map
> > > options.
> > > "
> > >
> > > Am I just confused by the description and that URL gives nothing more
> > > than ability to redistribute the routes better by matching on some of
> > > the parameters of other protocols, or is actual route filtering
> > > involved. And in case of the second, how would it even know which
> > > source protocol it originally came from. Sounds very logical, so just
> >
> > > wanted to do a sanity check.
> > >
> > > Thank you
> > >
> > > Yan
> > >
> > >
> > _______________________________________________________________________
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> >
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> >
>
>
>
> --
> Benedict Munyao
> Dimension Data
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