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New Member

Ping Fail from Core Switch

Hey,

We just installed some new switches at a remote site. A 3750X as the core switch and around 12 access layer switches distributed around different closets at the site.

On the core switch, when I ping without specifying a source I get some very inconsistant results. When I ping the loopback interface on the same switch I get a normal response:

WN-B3-CORE-3750X#ping 10.255.255.7

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.255.255.7, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms
WN-B3-CORE-3750X#

If I ping the router's loopback connected to the core switch I get a very slow response:

WN-B3-CORE-3750X#ping 10.255.255.6

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.255.255.6, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 302/337/403 ms
WN-B3-CORE-3750X#

If I ping the router's loopback connected to the core switch but, specify a source(any source that exists on the core switch) I get a normal response:

WN-B3-CORE-3750X#ping 10.255.255.6 source lo0

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.255.255.6, timeout is 2 seconds:
Packet sent with a source address of 10.255.255.7
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms
WN-B3-CORE-3750X#

If I ping an address on the other side of the WAN without specifying a source the ping fails.

Any ideas?

Some output:

WN-B3-CORE-3750X#sh cef state
CEF Status:
RP instance
common CEF enabled
IPv4 CEF Status:
CEF enabled/running
dCEF enabled/running
CEF switching enabled/running
universal per-destination load sharing algorithm, id CF615770
IPv6 CEF Status:
CEF disabled/not running
dCEF disabled/not running
universal per-destination load sharing algorithm, id CF615770

WN-B3-CORE-3750X#sh ip route 10.255.255.7

Routing entry for 10.255.255.7/32

  Known via "connected", distance 0, metric 0 (connected, via interface)

  Redistributing via eigrp 99

  Routing Descriptor Blocks:

  * directly connected, via Loopback0

      Route metric is 0, traffic share count is 1

Thank you

Everyone's tags (3)
1 REPLY
New Member

Ping Fail from Core Switch

Forget it - solved the issue. Router had wrong mask.Since we have 2 interfaces between the router and switch I was able to change them live. I tried to ping from the switch using all sources except for the actual physical interface connected to the router. I wonder if it would have failed if I used that? I'll lab it.

Thanks anyway, Pat.

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