Re: [OSL | CCIE_RS] Need Help in understanding sequence.

so what i can understand from above is that, what ever statements are there
set... all of those should match to have an action. But set ip default
next-hope is kinda fail safe option, if nothing else work it should work.

Best regards,

Nadeem Rafi

On Mon, Jan 25, 2010 at 12:03 AM, Joe Astorino <jastorino_at_ipexpert.com>wrote:

> Because the two set commands are looking at different values: The
> first two you mention (set ip next-hop and set ip next-hop
> verify-availability make their decisions based on a) if the next-hop
> you specify is in your routing table and b) if it is verified via CDP.
>
> The third set command (set ip default next-hop) looks at something
> different entirely -- It looks at the destination IP address. If you
> don't have a route for the destination, it will policy route to the
> next-hop that you set. The set ip default next-hop command is sort of
> like having a static route ONLY for the things that matched the
> access-list.
>
> On Sun, Jan 24, 2010 at 3:54 PM, Nadeem Rafi <nrafia_at_gmail.com> wrote:
> > i am sorry if i cannot elaborate my question. I will try again...
> > with match statement things will proceed to set commands.
> > set ip next hope ABC
> > will set next hop to ABC but only if
> > set ip next-hope verify-availability
> > CDP can verify that next hope is available. if its not available then set
> > command will not do any thing and will not set it to ABC.
> > quite clear upto this point.
> > BUT why logic take care of following? Why it should not skip it also?
> that
> > was what i want to ask :)
> > set ip default next-hope XYZ
> >
> > Best Regards,
> > Nadeem Rafi
> > On Sun, Jan 24, 2010 at 11:46 PM, Joe Astorino <jastorino_at_ipexpert.com>
> > wrote:
> >>
> >> I'm not sure I understand the question entirely, but there are
> >> fundamental differences in the commands here:
> >>
> >> 1) set ip next-hop <--- This will look at the next-hop address you
> >> specify. If that next-hop is in the routing-table, the packet is
> >> policy routed to that next-hop.
> >> 2) set ip default next-hop <--- This will look at the destination IP
> >> address in the header. If you have a route to the destination in your
> >> routing table the packet is NOT policy routed. If you don't have a
> >> route to the destination, then you are routed to the next-hop
> >> specified.
> >>
> >> The logic is different, and the two commands are looking at different
> >> fields. The first looks at next-hop and the second looks at the
> >> destination IP address to make decisions.
> >>
> >> HTH
> >>
> >> On Sun, Jan 24, 2010 at 1:32 PM, Nadeem Rafi <nrafia_at_gmail.com> wrote:
> >> > Route-map Policy_routing
> >> > match ip address FROM_X_TO_Y permit 10
> >> > set ip next hope ABC
> >> > set ip next-hope verify-availability
> >> > set ip default next-hope XYZ
> >> > how this will work? I know if cdp cannot verify reachability of next
> >> > hope then set ip next-hope ABC will not work. But why set ip default
> >> > will
> >> > work?
> >> > Sorry for such basic question...
> >> > Best Regards,
> >> > Nadeem rafi
> >> > _______________________________________________
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> >> >
> >>
> >>
> >>
> >> --
> >> Regards,
> >>
> >> Joe Astorino CCIE #24347 (R&S)
> >> Sr. Technical Instructor - IPexpert
> >> Mailto: jastorino_at_ipexpert.com
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>
>
> --
> Regards,
>
> Joe Astorino CCIE #24347 (R&S)
> Sr. Technical Instructor - IPexpert
> Mailto: jastorino_at_ipexpert.com
> Telephone: +1.810.326.1444
> Live Assistance, Please visit: www.ipexpert.com/chat
> eFax: +1.810.454.0130
>
> IPexpert is a premier provider of Classroom and Self-Study Cisco CCNA
> (R&S, Voice & Security), CCNP, CCVP, CCSP and CCIE (R&S, Voice,
> Security & Service Provider) Certification Training with locations
> throughout the United States, Europe and Australia. Be sure to check
> out our online communities at www.ipexpert.com/communities and our
> public website at www.ipexpert.com

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Received on Mon Jan 25 2010 - 00:11:21 ART