07-12-2012 10:10 PM - edited 03-04-2019 04:57 PM
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:
.....
07-12-2012 10:54 PM
HI,
Do you have any rate-limit applied on interface ?
Can you share sanitised configs please...
Regards,
Smitesh
07-13-2012 12:06 AM
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
07-13-2012 01:41 AM
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 .
07-13-2012 12:46 AM
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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