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Nirmal Behuria

Ping break in OSPF


    We are building a Network with 4 Core Routers,22 Aggregation Routers & 34 Edge Routers.

Core Routers                : Cisco CRS-1

Aggregation Routers     :  Cisco ASR9000

Edge Routers               : Cisco 7609/7613

We have a Data Center consisting of two nos. of Cisco6509-V-E switches along with two nos. of Csico 7613 & some servers.

Our WAN Network (outside Data Center) is almost ready & we need to connect it to Data Center so that we can show WAN Links in NNM.

For the time being, we are connecting just one Cisco6509-V-E directly to Aggregation Router (ASR9000 which is also residing in our Data Center) in order to show WAN links to Customer.This link is point to point link.

We have configured OSPF in the whole Network in area0.Cisco6509-V-E is also running OSPF for all its VLAN interfaces.

Problem: When we try to ping any WAN ip address of any of the Routers (Core or Aggregation) FROM ASR9000 router, we get full ping no matter what count it is.A 10,000 count ping also gets successful without any drop.

                But, when i ping any WAN address from my Cisco6509-V-E Switch, i get packet drops.Same issue with servers too,when i ping from any server i get packet drops.These drops are enough which are not allowing me to run any service in the Network.

        Cisco 6509 is showing all the routers in Data Base as well as Routing Table. But the ping breaks much when we ping some multihop address.It is vice versa,when we ping from outside some router to Data Center, we get breaks,but we don't get them apart from Data Center.

Is there is some specific configuration between IOS & IOS XR devices for OSPF to work smoothly.I am very much confused & in pressure to resolve the same so please help me in detail.

(Attaching Sh Tech of 6509,Sh run of ASR connected to CRS & show run of CRS connected to ASR)

Please let me know if the documents attached are sufficient or you need some more.


Mahesh Gohil
Rising star


I assume below is the current setup


Few questions to get more clarity.

> when you ping CRS ping is OK. is it?

> When you ping ASR9000 what is the result. (ping point y as well as point x)

> can you tell us what are those interface at point x and point y

> what are the servers pinging.



Hi Mahesh,

                  The setup you thought is corrent.

> when you ping CRS ping is OK. is it?

If i Ping CRS from 6500,i get breaks.If i ping CRS from ASR, its 100%.

> When you ping ASR9000 what is the result. (ping point y as well as point x)

I can ping ASR9000 any interface with 100% success from 6500.

> can you tell us what are those interface at point x and point y

X is TenGigE0/1/0/0

Y is Gigabit Etthernet Port (Copper)

> what are the servers pinging.

Every server is getting ping breaks.Our main server is HP Network Node Manager for topology view.

Kishore Chennupati
Rising star

Hi Shankar,

When pinging from the servers to the Routers you advised you are getting packet loss. Is there a particular fashion or pattern you see. like loosing packets after 5 pings etc. Maybe its because of Control plane policing. you might want to check that.

If you are going the other way around i.e from the routers to the servers and getting packet loss, then you need to check the speed, duplex MTU setting across the whole path.




Hi Kishore,

                  yes, it is like in a perticular fashion. I see after ,say,60 pings, i loose 5-6 pings,,then again 60 pings,,i loose 5-6 pings..Its in a fashion.

But OSPF Neighbour shows full adjacency.showling like "FULL/-"

What is Control Plane policy.Kindly tell me how to change it in a best way?

MTU was not configured in any of interfaces..I read in Cisco Document,,then I put "ip ospf MTU-ignore" in Cisco 6500,,but no effect!!

Hi Shanker,

1. You mentioned ping from servers or ping from 6500 is getting packet loss right? which IP address did you ping? You have mentioned  WAN address, does it means, an IP configured on CRS-1 box? or some other IOS box?.

1. if  the remote IP is on CRS-1, please check the LPTS (local packet transport service).  Like mentioned in the thread, CRS-1 enabled with default control plane protection technique.  You can verify the packet drops for the ICMP.


show lpts pifib hardware entry statistics location R/S/CPU0

show  lpts pifib hardware police location R/S/CPU0 (where R/S/O Ingress line card for the PING i.e the line card where the remote IP is configured ex 0/1/CPU0)

2. If you remote IP is on  IOS based router , please check whethet any COPP (control plane policing is enabled) and for testing purpose, disable it and check

sh policy-map control-plane


Hi Meenakshi,

                     I get ping breaks when i ping from Cisco 6500 or any other server connected to it destined to:

-Any loopback ip configured on Cisco CRS-1,Cisco ASR9K or Cisco 7600 series router.

-Any interface ip configured on Cisco CRS-1,Cisco ASR9K or Cisco 7600 series router.

I will try the commands you told tomarrow & will get back to ya with results.


Wanted to verify with what packet size you are pinging, the asr9k doesn't do fragmentation in hardware and everything gets sent to the CPU for processing then in order to fragmentation.

To find out if the 9k is part of the issue you can do the following troubleshooting guide for packet tracing within the 9k:

ASR9000 packet troubleshooting and understanding NP drop counters

The CRS is known to have very strict LPTS policers for locally destined Low priority traffic such as ICMP pings, hence you will see losses

with a larger amount of pings.

the show lpts commands provided earlier .

From the further tests you've done, it looks like you might be looking at the 6k for this particular issue.


Xander Thuijs - CCIE #6775

Sr Tech Lead ASR9000

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