alt.certification.cisco - Problem with route maps

Author

Problem with route maps

Robert Bowen

2002-12-27, 3:24 pm

I have inherited a network where a route map was setup before I arrived.
All looks well as it seems to accomplish its purpose.

The route map was setup to route all traffic to and from the 192.168.60.0/22
network out a single T-1 line. The other 3 T-1 lines are for the rest of
the users. Problem is that when the T-1 line goes down for the
192.168.60.0 network, we don't want their traffic going out any of the other
T-1 lines.

From what I understand this did work at some point in time. When I shut
down the interface with the single T-1 line traffic for that network pauses
for a few seconds and then goes out one of the other T-1 lines.

Trace commands show all traffic exiting the correct T-1 line until the
interface is disabled. Then the traffic goes out one of the other 3
interfaces.

I can place an ACL on each of the T-1 lines that I don't want the traffic
exiting on. I would prefer not to.

I put a small diagram of the design at this URL
http://www.baldwinschools.org/nwmap.gif
The sanitized configuration files are included below.

I would appreciate any help. Please feel free to e-mail with any
questions.

Thank you and have a good weekend,
Robert
bowenr@baldwin.k12.ny.us

ROUTER CONFIGURATION FILE
!
ip subnet-zero
no ip source-route
ip cef
!
!
no ip domain-lookup
!
interface Ethernet0/0
description Feed to Students (VL60)
ip address 192.168.63.253 255.255.252.0
no ip mroute-cache
ip policy route-map Student_Internet
full-duplex
!
interface Serial0/0
description Single T-1 line for students
ip address 147.55.245.22 255.255.255.252
encapsulation ppp
no ip mroute-cache
!
interface Serial0/1
description Bundle1-1
ip address 147.55.245.78 255.255.255.252
ip load-sharing per-packet
encapsulation ppp
no ip mroute-cache
!
interface Ethernet1/0
description connected to EthernetLAN
ip address 192.168.251.252 255.255.252.0
no ip mroute-cache
half-duplex
!
interface Serial1/0
description Bundle1-2
ip address 147.55.245.82 255.255.255.252
ip load-sharing per-packet
encapsulation ppp
no ip mroute-cache
!
interface Serial1/1
description Bundle1-3
ip address 147.55.245.86 255.255.255.252
ip load-sharing per-packet
encapsulation ppp
no ip mroute-cache
!
ip local policy route-map net-STUDENT
ip classless
ip route 0.0.0.0 0.0.0.0 Serial1/0
ip route 0.0.0.0 0.0.0.0 Serial1/1
ip route 0.0.0.0 0.0.0.0 Serial0/1
no ip http server
ip pim bidir-enable
!
access-list 10 permit 192.168.60.0 0.0.3.255
access-list 50 permit 192.168.60.0 0.0.3.255
access-list 120 permit ip 192.168.60.0 0.0.3.255 any
route-map net-STUDENT permit 10
match ip address 120
set ip next-hop 147.55.245.21
!
route-map Student_Internet permit 10
match ip address 120
set ip next-hop 147.55.245.21
!
!
end

MSFC CONFIGURATION (MAIN ROUTER FOR ORGANIZATION)

!
version 12.1
no service pad
service timestamps debug uptime
service timestamps log uptime
service password-encryption
!
ip subnet-zero
!
!
no ip finger
no ip domain-lookup
!
!
interface Vlan1
ip address 192.168.1.254 255.255.255.0
no ip route-cache
no ip mroute-cache
!
interface Vlan60
ip address 192.168.63.254 255.255.252.0
no ip route-cache
no ip mroute-cache
ip policy route-map Student_Connect
!
interface Vlan248
ip address 192.168.251.248 255.255.252.0
no ip route-cache
no ip mroute-cache
!
ip classless
ip route 0.0.0.0 0.0.0.0 192.168.251.252
no ip http server
!
access-list 190 permit ip 192.168.60.0 0.0.3.255 192.168.0.0 0.0.255.255
access-list 191 permit ip 192.168.60.0 0.0.3.255 any

route-map Student_Connect permit 10
match ip address 190
set ip next-hop 192.168.63.253
!
route-map Student_Connect permit 20
match ip address 191
set ip next-hop 192.168.63.253
!
end

Barry Margolin

2002-12-27, 4:24 pm

In article <O%2P9.171224$a8.84425@news4.srv.hcvlny.cv.net>,
Robert Bowen <bowenr@baldwin.k12.ny.us> wrote:
>I have inherited a network where a route map was setup before I arrived.
>All looks well as it seems to accomplish its purpose.
>
>The route map was setup to route all traffic to and from the 192.168.60.0/22
>network out a single T-1 line. The other 3 T-1 lines are for the rest of
>the users. Problem is that when the T-1 line goes down for the
>192.168.60.0 network, we don't want their traffic going out any of the other
>T-1 lines.
>
>From what I understand this did work at some point in time. When I shut
>down the interface with the single T-1 line traffic for that network pauses
>for a few seconds and then goes out one of the other T-1 lines.

Instead of "set ip next-hop 147.55.245.21", use "set ip interface Serial0/0".

When the interface is shut down, the router no longer has a route for
147.55.245.20/30, so it ends up using the default route to get to the next
hop, which causes it to use the other T-1 lines. When you point the route
to an interface instead of an address, it can't do this kind of recursive
routing, and the traffic simply fails.

--
Barry Margolin, barmar@genuity.net
Genuity, Woburn, MA
*** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.
Please DON'T copy followups to me -- I'll assume it wasn't posted to the group.

Hansang Bae

2002-12-27, 7:24 pm

In article <Hu3P9.13$fU2.247@paloalto-snr1.gtei.net>, barmar@genuity.net
says...
[snip]
> Instead of "set ip next-hop 147.55.245.21", use "set ip interface Serial0/0".

"set interface Serial0/0"

--

hsb

"Somehow I imagined this experience would be more rewarding" Calvin
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AEM Networking

2002-12-28, 11:24 am

Let me know if this works...Using an interface to point to a route tells the
router to use proxy arp so you may have to turn off proxy arp on the Serial
Interfaces,

no ip proxy-arp or no proxy-arp, something like that

Also using an interface as a route can cause problems with cef. After you
do this, check the cef table.

www.aemnetworking.com

"Barry Margolin" <barmar@genuity.net> wrote in message
news:Hu3P9.13$fU2.247@paloalto-snr1.gtei.net...
> In article <O%2P9.171224$a8.84425@news4.srv.hcvlny.cv.net>,
> Robert Bowen <bowenr@baldwin.k12.ny.us> wrote:
> >I have inherited a network where a route map was setup before I arrived.
> >All looks well as it seems to accomplish its purpose.
> >
> >The route map was setup to route all traffic to and from the
192.168.60.0/22
> >network out a single T-1 line. The other 3 T-1 lines are for the rest
of
> >the users. Problem is that when the T-1 line goes down for the
> >192.168.60.0 network, we don't want their traffic going out any of the
other

> >T-1 lines.
> >
> >From what I understand this did work at some point in time. When I
shut
> >down the interface with the single T-1 line traffic for that network
pauses
> >for a few seconds and then goes out one of the other T-1 lines.
>
> Instead of "set ip next-hop 147.55.245.21", use "set ip interface
Serial0/0".
>
> When the interface is shut down, the router no longer has a route for
> 147.55.245.20/30, so it ends up using the default route to get to the next
> hop, which causes it to use the other T-1 lines. When you point the route
> to an interface instead of an address, it can't do this kind of recursive
> routing, and the traffic simply fails.
>
> --
> Barry Margolin, barmar@genuity.net
> Genuity, Woburn, MA
> *** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to
newsgroups.
> Please DON'T copy followups to me -- I'll assume it wasn't posted to the
group.

Barry Margolin

2002-12-30, 10:24 am

In article <BRkP9.480558$WL3.125693@rwcrnsc54>,
AEM Networking <aemnetworking@aemnetworking.com> wrote:
>Let me know if this works...Using an interface to point to a route tells the
>router to use proxy arp so you may have to turn off proxy arp on the Serial
>Interfaces,

There's no such thing as ARP on a point-to-point serial line, since there
are no addresses needed. A packet goes in one end and comes out the other.

>Also using an interface as a route can cause problems with cef. After you
>do this, check the cef table.

We point all our customer routes to interfaces rather than addresses and
don't have problems.

--
Barry Margolin, barmar@genuity.net
Genuity, Woburn, MA
*** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.
Please DON'T copy followups to me -- I'll assume it wasn't posted to the group.

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