Interface Source IP Cannot Ping the Gateway of Last Resort / Default-Gateway

[Matthew Martin]

Hello All,

I am trying to get a routed interface on a 3560 to talk to the default-gateway of the same 3560. I have IP Routing enabled and I have the ip route configured for last resort to go to that same default-gateway, but the pings fail when sourced from that interface. If I do not source the pings I can ping the default-gateway just fine. What am I missing here?

The interface I am trying to ping from is Fa0/2 and the default-gateway is connected to Fa0/1...

3560 Switch Config Contains:

!
ip routing
!
!......
!
interface FastEthernet0/1
 description uplink to 4510
 switchport trunk encapsulation dot1q
 switchport mode trunk
!
interface FastEthernet0/2
 no switchport
 ip address 10.241.241.1 255.255.255.0
!
!......
!
interface Vlan1
 ip address 192.168.3.3 255.255.255.0
!
ip default-gateway 192.168.3.2
ip classless
ip route 0.0.0.0 0.0.0.0 192.168.3.2
ip http server
!

Here are the results of the ping:

SWITCH#ping 192.168.3.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.3.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms
SWITCH#
SWITCH#
SWITCH#ping 192.168.3.2 source 10.241.241.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.3.2, timeout is 2 seconds:
Packet sent with a source address of 10.241.241.1
.....
Success rate is 0 percent (0/5)
SWITCH#

Any ideas what I may be missing here? I am using this for testing a new router and switch which are connected to Fa0/2 (*other end of Fa0/2 is an ISR4321 Router, which you can see in show cdp below, and connected to that ISR is a 2960-X switch). This is the 2nd group of the same exact type of ISR router and switch that I am testing. The 1st group was working just fine. Now, after I've configured this 2nd group and it suddenly stopped working...

Show CDP Neighbor on SWITCH:

SWITCH#
SWITCH#show cdp nei
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone

Device ID     Local Intrfce Holdtme Capability Platform   Port ID
ISR-4321-Rtr2 Fas 0/2       174     R          ISR4321/K  Gig 0/0/0
4510R         Fas 0/1       153     R S I      WS-C4510R  Gig 9/22
SWITCH#

Any thoughts or suggestions would be greatly appreciated!

Thanks in Advance,
Matt

[acampbell · Accepted solution]

Hi Mathew,

You have proved that 192.68.3.2 is alive down fas0/1 with your ping :)

But does the device 192.168.3.2 have a route back via your switch address 192.168.3.1 to subnet 10.241.241.0/24.

Regards
Alex

[Matthew Martin]

Hey Alex, thanks for the reply, much appreciated.

Excellent, thanks to your comment I was able to figure it out.! Like you were saying, there was a route to 192.168.3.2, but there was not a route back to 10.241.241.x... So adding this route below to the 4510, which is on Fa0/1, I am now able to get to all the subnets on the 4510.

ip route 10.241.241.0 255.255.255.0 192.168.3.3

The 192.168.3.3 address is the IP of the switch between my new ISR router that I'm configuring and the 4510... Many thanks!

Thanks Again,
Matt