06-04-2014 12:50 AM - edited 03-04-2019 11:05 PM
Dear all,
Please i have been having these logging:
*Jun 4 06:52:20.366: %IP_VFR-4-FRAG_TABLE_OVERFLOW: FastEthernet0/1: the fragment table has reached its maximum threshold 32
*Jun 4 07:00:31.574: %IP_VFR-4-FRAG_TABLE_OVERFLOW: FastEthernet0/0: the fragment table has reached its maximum threshold 16
First I don't understand the different between Ip virtual-reassembly in and out.
when I configured the interfaces the default is in.
i can see it with show ip virtual-reassembly (interface).
here is my interfaces config:
interface FastEthernet0/0
description <<""Inside"">>
ip address x.x.x.x 255.255.255.0
ip pim sparse-mode
ip nat inside
ip virtual-reassembly
duplex auto
speed auto
!
interface FastEthernet0/1
description <<""Internet"">>
ip address Real IP address
ip nat outside
ip virtual-reassembly
duplex auto
speed auto
And here is my show ip virtual-reassembly for my both interfaces.
#sh ip virtual-reassembly fa 0/0
FastEthernet0/0:
Virtual Fragment Reassembly (VFR) is ENABLED [in]
Concurrent reassemblies (max-reassemblies): 16
Fragments per reassembly (max-fragments): 32
Reassembly timeout (timeout): 3 seconds
Drop fragments: OFF
Current reassembly count:0
Current fragment count:0
Total reassembly count:6364092
Total reassembly timeout count:3
sh ip virtual-reassembly fa 0/1
FastEthernet0/1:
Virtual Fragment Reassembly (VFR) is ENABLED [in]
Concurrent reassemblies (max-reassemblies): 16
Fragments per reassembly (max-fragments): 32
Reassembly timeout (timeout): 3 seconds
Drop fragments: OFF
Current reassembly count:0
Current fragment count:0
Total reassembly count:10985
Total reassembly timeout count:1533
And when the messages start to appear in the logging the Internet start to get really slow.
Please help me with this problem.
Thanks and regards,
Mohamed Selim.
06-04-2014 05:18 AM
Hi there,
Prima facie it looks like MTU problem, as there is fragmentation happening, Check for MTU along the path.
HTH
Hitesh
06-04-2014 05:42 AM
Dear Hitesh,
My MTU on both interfaces is 1500,
when I open the drop fragment on the interfaces the message is gone..
And my ISP MTU is 1700.
Thanks and regards,
Mohamed Selim.
06-04-2014 05:52 AM
Hi,
Ping from a PC behind the router using option -f -l 1500 and see if makes through to find out path MTU to google or any public IP on the network. Also try extending the buffers on the interface.
ip virtual-reassembly max-fragments xxx max-reassemblies xxx
also you can check your MTU online
http://www.letmecheck.it/mtu-test.php
HTH
Hitesh
06-04-2014 06:00 AM
hi,
here is what appeared to me
Pinging 8.8.8.8 with 1500 bytes of data:
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Ping statistics for 8.8.8.8:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),
And this is my new config now under the interfaces:
interface FastEthernet0/0
description <<""Inside"">>
ip address x.x.x.x 255.255.255.0
ip pim sparse-mode
ip nat inside
ip virtual-reassembly in drop-fragments timeout 5
duplex auto
speed auto
!
interface FastEthernet0/1
description <<""Internet"">>
ip address Real IP
no ip proxy-arp
ip nat outside
ip virtual-reassembly in drop-fragments timeout 5
duplex full
speed 100
and here is the show ip virtual
#sh ip virtual-reassembly
FastEthernet0/0:
Virtual Fragment Reassembly (VFR) is ENABLED [in]
Concurrent reassemblies (max-reassemblies): 16
Fragments per reassembly (max-fragments): 32
Reassembly timeout (timeout): 5 seconds
Drop fragments: ON
Current reassembly count:0
Current fragment count:0
Total reassembly count:0
Total reassembly timeout count:0
FastEthernet0/1:
Virtual Fragment Reassembly (VFR) is ENABLED [in]
Concurrent reassemblies (max-reassemblies): 16
Fragments per reassembly (max-fragments): 32
Reassembly timeout (timeout): 5 seconds
Drop fragments: ON
Current reassembly count:0
Current fragment count:0
Total reassembly count:0
Total reassembly timeout count:0
Thanks.
06-04-2014 06:05 AM
hi,
see these discussion:
https://supportforums.cisco.com/discussion/10350421/ipvfr-3-overlapfragments
https://supportforums.cisco.com/discussion/11027121/ipvfr-4-fragtableoverflow
Regards,
kazim
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