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Can Ping Switch but Can't Ping Rtr (behind it)

 
 
Bob Simon
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      11-05-2003
I am at home (68.0.56.75) and can ping my company's 2924 switch
(public address: x.y.34.2) but not a 2500 lab router behind it (public
address: x.y.34.4). However, if I telnet to the switch, I can then
ping or telnet to the 2500. I am able to ping all the other devices
attached to the switch from home, why not the 2500?

The config for the switch and router ports follow:
SWITCH
>show int f0/19

FastEthernet0/19 is up, line protocol is up
Hardware is Fast Ethernet, address is 0030.7bdd.8c13 (bia
0030.7bdd.8c13)
Description: Cisco 2500
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Auto-duplex (Half), Auto Speed (10), 100BaseTX/FX
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:58, output 00:00:01, output hang never
Last clearing of "show interface" counters 01:11:12
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 5000 bits/sec, 10 packets/sec
768 packets input, 68420 bytes
Received 283 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 71 multicast
0 input packets with dribble condition detected
44727 packets output, 7433576 bytes, 0 underruns
0 output errors, 22 collisions, 0 interface resets
0 babbles, 0 late collision, 2 deferred
0 lost carrier, 0 no carrier
419 output buffer failures, 0 output buffers swapped out

ROUTER
#show int e0
Ethernet0 is up, line protocol is up
Hardware is Lance, address is 0000.0c5d.1126 (bia 0000.0c5d.1126)
Internet address is x.y.34.4 255.255.255.0
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, rely 255/255, load
1/255
Encapsulation ARPA, loopback not set, keepalive set (10 sec)
ARP type: ARPA, ARP Timeout 4:00:00
Last input 0:00:00, output 0:00:00, output hang never
Last clearing of "show interface" counters 0:01:49
Output queue 0/40, 0 drops; input queue 23/75, 0 drops
5 minute input rate 8000 bits/sec, 13 packets/sec
5 minute output rate 1000 bits/sec, 3 packets/sec
2323 packets input, 142399 bytes, 0 no buffer
Received 2234 broadcasts, 0 runts, 0 giants
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 input packets with dribble condition detected
80 packets output, 6223 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets, 0 restarts
0 output buffer failures, 0 output buffers swapped out

Also, debug ip packet on the switch shows that it receives icmp
packets from my home pc to it, but not when I ping the router. What
could cause this?
 
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Rik Bain
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      11-05-2003
On Thu, 06 Nov 2003 11:41:44 +0600, Walter Roberson wrote:

> In article <(E-Mail Removed)>, Bob Simon
> <(E-Mail Removed)> wrote:
> :I found my problem! I was missing the following statement in the
> :router:
> :ip route 0.0.0.0 0.0.0.0 x.y.34.1 1
>
> :I had this instead (which did not work): :ip default-gateway x.y.34.1
>
> :I thought that 0.0.0.0/0 WAS the default gateway. I guess not! :What's
> the difference between these two statements?
>
> If I recall correctly, default-gateway is the gateway of last resort if
> all the routing protocols fail.


ip default-gateway, IIRC, is only for traffic from the router (i.e. TFTP,
telnet, et al.) when ip routing is disabled.

Rik
 
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Bob Simon
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      11-06-2003
On 5 Nov 2003 13:51:50 -0800, http://www.velocityreviews.com/forums/(E-Mail Removed) (Bob Simon)
wrote:

>I am at home (68.0.56.75) and can ping my company's 2924 switch
>(public address: x.y.34.2) but not a 2500 lab router behind it (public
>address: x.y.34.4). However, if I telnet to the switch, I can then
>ping or telnet to the 2500. I am able to ping all the other devices
>attached to the switch from home, why not the 2500?


I have some more info:
I can successfully ping both the switch and router from another
computer that is directly connected to the switch. I cannot ping the
router from another host that is off-net.

Thinking that perhaps my ISP's managed router (not under my control)
is blocking x.y.34.4, I changed the router's IP address to x.y.34.14.
This did not help.

Anyone got any other ideas for me to try?

--
Bob Simon
remove x from domain for private replies
 
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Scooby
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      11-06-2003
Try a trace (tracert in windows) from your pc to the router and then a trace
from the router to your pc - that will at least tell you where the packets
are getting dropped or routed improperly.



"Bob Simon" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> On 5 Nov 2003 13:51:50 -0800, (E-Mail Removed) (Bob Simon)
> wrote:
>
> >I am at home (68.0.56.75) and can ping my company's 2924 switch
> >(public address: x.y.34.2) but not a 2500 lab router behind it (public
> >address: x.y.34.4). However, if I telnet to the switch, I can then
> >ping or telnet to the 2500. I am able to ping all the other devices
> >attached to the switch from home, why not the 2500?

>
> I have some more info:
> I can successfully ping both the switch and router from another
> computer that is directly connected to the switch. I cannot ping the
> router from another host that is off-net.
>
> Thinking that perhaps my ISP's managed router (not under my control)
> is blocking x.y.34.4, I changed the router's IP address to x.y.34.14.
> This did not help.
>
> Anyone got any other ideas for me to try?
>
> --
> Bob Simon
> remove x from domain for private replies



 
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Bob Simon
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Posts: n/a
 
      11-06-2003
I found my problem! I was missing the following statement in the
router:
ip route 0.0.0.0 0.0.0.0 x.y.34.1 1

I had this instead (which did not work):
ip default-gateway x.y.34.1

I thought that 0.0.0.0/0 WAS the default gateway. I guess not!
What's the difference between these two statements?
Bob

On Thu, 06 Nov 2003 02:08:15 GMT, "Scooby"
<(E-Mail Removed)> wrote:

>Try a trace (tracert in windows) from your pc to the router and then a trace
>from the router to your pc - that will at least tell you where the packets
>are getting dropped or routed improperly.
>
>
>
>"Bob Simon" <(E-Mail Removed)> wrote in message
>news:(E-Mail Removed).. .
>> On 5 Nov 2003 13:51:50 -0800, (E-Mail Removed) (Bob Simon)
>> wrote:
>>
>> >I am at home (68.0.56.75) and can ping my company's 2924 switch
>> >(public address: x.y.34.2) but not a 2500 lab router behind it (public
>> >address: x.y.34.4). However, if I telnet to the switch, I can then
>> >ping or telnet to the 2500. I am able to ping all the other devices
>> >attached to the switch from home, why not the 2500?

>>
>> I have some more info:
>> I can successfully ping both the switch and router from another
>> computer that is directly connected to the switch. I cannot ping the
>> router from another host that is off-net.
>>
>> Thinking that perhaps my ISP's managed router (not under my control)
>> is blocking x.y.34.4, I changed the router's IP address to x.y.34.14.
>> This did not help.
>>
>> Anyone got any other ideas for me to try?
>>
>> --
>> Bob Simon
>> remove x from domain for private replies

>



--
Bob Simon
remove x from domain for private replies
 
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Walter Roberson
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Posts: n/a
 
      11-06-2003
In article <(E-Mail Removed)>,
Bob Simon <(E-Mail Removed)> wrote:
:I found my problem! I was missing the following statement in the
:router:
:ip route 0.0.0.0 0.0.0.0 x.y.34.1 1

:I had this instead (which did not work):
:ip default-gateway x.y.34.1

:I thought that 0.0.0.0/0 WAS the default gateway. I guess not!
:What's the difference between these two statements?

If I recall correctly, default-gateway is the gateway of last resort
if all the routing protocols fail.
--
Any sufficiently advanced bug is indistinguishable from a feature.
-- Rich Kulawiec
 
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Pete Mainwaring
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Posts: n/a
 
      11-06-2003
"Scooby" <(E-Mail Removed)> wrote in message news:<j2iqb.11894$(E-Mail Removed) hlink.net>...
> Try a trace (tracert in windows) from your pc to the router and then a trace
> from the router to your pc - that will at least tell you where the packets
> are getting dropped or routed improperly.
>
>
>
> "Bob Simon" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
> > On 5 Nov 2003 13:51:50 -0800, (E-Mail Removed) (Bob Simon)
> > wrote:
> >
> > >I am at home (68.0.56.75) and can ping my company's 2924 switch
> > >(public address: x.y.34.2) but not a 2500 lab router behind it (public
> > >address: x.y.34.4). However, if I telnet to the switch, I can then
> > >ping or telnet to the 2500. I am able to ping all the other devices
> > >attached to the switch from home, why not the 2500?

> >
> > I have some more info:
> > I can successfully ping both the switch and router from another
> > computer that is directly connected to the switch. I cannot ping the
> > router from another host that is off-net.
> >
> > Thinking that perhaps my ISP's managed router (not under my control)
> > is blocking x.y.34.4, I changed the router's IP address to x.y.34.14.
> > This did not help.
> >
> > Anyone got any other ideas for me to try?
> >
> > --
> > Bob Simon
> > remove x from domain for private replies


Check the routing on the 2500 - does it have a return route to your
home (68.0.56.75) address or a default route? If you can't ping the
2500 from anywhere other than the network that it is directly
connected to, I reckon it hasn't got the necessary routing statements.

Pete
 
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Andre Beck
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Posts: n/a
 
      11-09-2003
Bob Simon <(E-Mail Removed)> writes:
>
> I found my problem! I was missing the following statement in the
> router:
> ip route 0.0.0.0 0.0.0.0 x.y.34.1 1
>
> I had this instead (which did not work):
> ip default-gateway x.y.34.1
>
> I thought that 0.0.0.0/0 WAS the default gateway. I guess not!
> What's the difference between these two statements?


The "ip default-gateway" statement is only significant when you configure
"no ip routing", whereas the explicit declaration of a 0.0.0.0/0 static
route is only significant when you configure "ip routing".

--
The _S_anta _C_laus _O_peration
or "how to turn a complete illusion into a neverending money source"

-> Andre "ABPSoft" Beck +++ ABP-RIPE +++ Dresden, Germany, Spacetime <-
 
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John Lamar
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      01-19-2005
Yes, you need a default route for all other traffic other than your
directly connected network... however the 2500 knows where the switch
is so you are in good shape.

The problem is between you and your switch. Actually that doesn't make
sense. Your isp gets you to the switch, the x.y.3.0 network....
something before that switch knows about this network also. Turn on the
appropriate routing protocols on both devices and you should be in good
shape.

If the switch is then connected to a router or gateway on the other
side that allows it on the internet make that path (that adapter's
network) the default route.

 
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