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The ICMP packet can't transit between cisco 7609 router

liuluht
Level 1
Level 1

We have two 7609 routers at different city . Our both 7609 routers make MTU 1800 bytes and when I ping the other router with  packet (1500 bytes) ,it can get thought .But when I ping with 15000 even 1506 bytes ,it didn.t work .As I didn't  disable the DF field .Please tell me why ?

Internet address is 202.112.38.54/30

  MTU 1800 bytes, BW 1000000 Kbit, DLY 10 usec,

     reliability 255/255, txload 96/255, rxload 81/255

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

ping

Protocol [ip]:

Target IP address:  202.112.38.53   

Repeat count [5]: 5

Datagram size [100]: 1502

Timeout in seconds [2]:

Extended commands [n]:

Sweep range of sizes [n]:

Type escape sequence to abort.

Sending 5, 1502-byte ICMP Echos to 202.112.38.53, timeout is 2 seconds:

!!!!!

ping

Protocol [ip]:

Target IP address:  202.112.38.53

Repeat count [5]: 5

Datagram size [100]: 1506

Timeout in seconds [2]:

Extended commands [n]:

Sweep range of sizes [n]:

Type escape sequence to abort.

Sending 5, 1506-byte ICMP Echos to 202.112.38.53, timeout is 2 seconds:

.....

4 Replies 4

HI,

Do you have any rate-limit applied on interface ?

Can you share sanitised configs please...

Regards,

Smitesh

I didn't have any rate-limit applied on the  interface .

interface GigabitEthernet2/3

mtu 1800

bandwidth 1000000

ip address 202.112.38.54 255.255.255.252

no ip redirects

no ip unreachables

no ip proxy-arp

ip flow ingress

ip pim sparse-mode

ip ospf cost 80

end

Hi

Thank you for your answer . The link between them is  dark filber .And the fiber is leased line from another company .There is not  anyother network device (router) . The company reported there isn't error code on the line .We have eliminate the cause

of line .

Giuseppe Larosa
Hall of Fame
Hall of Fame

Hello Liuluht,

the two C7600 are in different cities. The link between them is provided by a SP or it is dark filber?

In the first case you may be facing an MTU limitation on the service provided by the SP, your devices are configured with an MTU of 1800, so they do not fragment the packets when sending on the link, but the packets may be too big for the SP network devices.

Hope to help

Giuseppe

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