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Every other Ping times out

Hello,

I have a unique situation.  Below is the output from a ping to google.com sourcing different interfaces:

pag1rtr01#ping google.com so gi0/2

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 74.125.21.138, timeout is 2 seconds:

Packet sent with a source address of 192.168.6.1

!.!.!

Success rate is 60 percent (3/5), round-trip min/avg/max = 4/4/4 ms

pag1rtr01#

pag1rtr01#

pag1rtr01#ping google.com so gi0/0

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 74.125.21.138, timeout is 2 seconds:

Packet sent with a source address of 10.92.4.3

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/8 ms

pag1rtr01#

pag1rtr01#

pag1rtr01#ping google.com so gi0/1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 74.125.21.138, timeout is 2 seconds:

Packet sent with a source address of 10.20.4.1

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms

pag1rtr01#

pag1rtr01#

pag1rtr01#ping google.com so gi0/1.2

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 74.125.21.138, timeout is 2 seconds:

Packet sent with a source address of 172.29.0.1

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms

pag1rtr01#

The ping output in bold above is the one in question.  As you can see, the other interfaces don't have this problem.  We are using a route map to change the normal routing behavior for this particular network only.  When I ping from this interface, every other ping times out.  This router is at a remote location and is connected to our corporate office via a transit router as seen here:

                            REMOTE-ROUTER (Gi0/0) -----> (Gi0/0)TRANSIT-ROUTER(Gi0/2) ------> (Gi3/26)CORE-SWITCH

The remote router is advertising the 192.168.6.0/24 network in EIGRP.  The transit router uses a distribute list to deny this network from being advertised into our corporate network.  The transit router is the router where we have the route map configured.  The configuration for it is as follows:

access-list 60 permit 192.168.6.0 0.0.0.255

route-map patnet_isp_access permit 10

match ip address 60

set ip default next-hop 192.168.60.1

This transit router has an interface configured on the 192.168.60.0/22 network, in which the IP is 192.168.60.38 and we have a route back on the firewall so that return traffic can get back to the 192.168.6.0/24 network in which the next hop IP would be 192.168.60.38.  Provided the information given, can anyone point me in the right direction as to why every other ping times out?  I can provide more info if needed.  Thanks!

Regards,

Terence

4 REPLIES
New Member

Every other Ping times out

If not already set try setting your speed and duplex on the interface.

duplex full

speed 100 or speed 1000 depending on what your gig port is connected to.

Hall of Fame Super Gold

Every other Ping times out

Terence

I have seen the behavior where every other ping times out in situations where at some hop there were equal cost links creating load sharing and one path had a return route and one path did not have a return route. I have also seen the behavior when some device was doing rate limiting. I can not be sure from your description whether either of these might explain your situation.

One thing about your situation is not clear to me and I hope that you can provide some clarification. Your route map does a set default next-hop and not a set next-hop. I am not clear why this is done. And it is not clear to me when your ping packet gets to the transit router whether there is an entry in the routing table for the destination (no default next-hop does not apply) or whether there is not an entry for the destination and the default is used.

HTH

Rick

New Member

Every other Ping times out

If you are using an ethernet cable, are you using a straight-thru from router to router instead of a crossover? Doesn't hurt to check.

Every other Ping times out

Hello Terrence and Others,

I totally agree with Rick on this one regarding the fact that there got to be at some point in the network a device where Load-Balancing is occuring and packets are just getting lost on one of the available paths (this is the most commom cause).

Now regarding the set ip default-next hop. I guess you have a default route on that router. If you do you are going to be just fine as packets will get policy based routed.

Make sure you check the entire path from the REMOTE-ROUTER to the ISP looking for a the route to the internet and also the route back to the 192.168.6.0

Looking for some Networking Assistance? 
Contact me directly at jcarvaja@laguiadelnetworking.com

I will fix your problem ASAP.

Cheers,

Julio Carvajal Segura
http://laguiadelnetworking.com

Julio Carvajal
Senior Network Security and Core Specialist
CCIE #42930, 2xCCNP, JNCIP-SEC
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