From: Kenneth Wygand (KWygand@customonline.com)
Date: Tue Jun 22 2004 - 16:51:34 GMT-3
Rexperts,
Since your backup "default ip route" statements for your E1/0 interface
points to a directly connected >BROADCAST< interface, your routing table
thinks all networks are directly connected and will thus arp for all
addresses. This will work provided the next-hop router on your
Ethernet1/0 interface is providing "proxy-arp" services (default on a
Cisco box).
Do a 'debug ip packet'. Are you getting "encapsulation failed" messages
when your T1 circuit is down? If so, one solution is to set your default
route to an IP address for next-hop instead of a directly connected
interface (specifically because this is a broadcast interface).
P.S. The reason this works is because a route to an IP address is
basically a recursive lookup, that continues looking up destination IP
addresses until it locates a next-hop interface (directly connected) out
which it can forward a packet.
Kenneth E. Wygand
Systems Engineer, Project Services
CISSP #37102, CCNP, CCDP, ACSP, Cisco IPT Design Specialist, MCP, CNA,
Network+, A+
Custom Computer Specialists, Inc.
"The only unattainable goal is the one not attempted."
-Anonymous
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
rexperts
Sent: Tuesday, June 22, 2004 3:17 PM
To: Howard C. Berkowitz; ccielab@groupstudy.com
Subject: Failover: 2nd Interface not working
When the T1 goes down the back-up interface Ethernet 1/0 does not kick
in.
I am thanking you in advance for your assistance.
Here is the config:
interface FastEthernet0/0
ip address 172.16.16.41 255.255.255.248
ip nat inside
speed auto
!
interface Serial0/0
description T1
ip unnumbered FastEthernet0/0
encapsulation ppp
no fair-queue
service-module t1 timeslots 1-24
!
interface Ethernet1/0
ip address dhcp
ip nat outside
half-duplex
!
ip nat inside source list 1 interface Ethernet1/0 overload
ip classless
ip route 0.0.0.0 0.0.0.0 Serial0/0
ip route 0.0.0.0 0.0.0.0 Ethernet1/0 20
no ip http server
!
access-list 1 permit any log
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