asked on

CISCO1921/K9 IP_VFR-4-FRAG_TABLE_OVERFLOW

Hello Experts,

I have upgraded our copper ADSL line ( 4MB) to Fiber Optic 100 MB Internet Connection.

I am receiving following warning on our cisco router 1921

*Nov 19 09:40:12.123: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Dialer0: the fragment table
has reached its maximum threshold 64

Can someone please advise on the cause and the fix please.

Some outputs

interface Dialer0
ip address negotiated
ip mtu 1492
ip nat outside
ip virtual-reassembly in max-reassemblies 64
encapsulation ppp
dialer pool 1
dialer-group 1
ppp authentication pap chap callin
ppp chap hostname XXXXXXXXXX
ppp chap password 0 8730
ppp pap sent-username XXXXXXXXXXX password 0 8730
no cdp enable
end

interface Dialer0
ip address negotiated
ip mtu 1492
ip nat outside
ip virtual-reassembly in max-reassemblies 64
encapsulation ppp
dialer pool 1
dialer-group 1
ppp authentication pap chap callin
ppp chap hostname 126652897@stc.net.sa
ppp chap password 0 8730
ppp pap sent-username 126652897@stc.net.sa password 0 8730
no cdp enable
end

Dialer0:
Virtual Fragment Reassembly (VFR) is ENABLED [in]
Concurrent reassemblies (max-reassemblies): 64
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:2590809
Total reassembly timeout count:37

Thanks

ASKER CERTIFIED SOLUTION

thrigger

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Ernie Beek

Normally one of the causes of fragmentation could be a wrongly set mtu. From the top of my head 1492 should be ok for a ppp connection but you might want to check (with your ISP).
The other thing you can do is, like thrigger said, raise the value of the reassembly (though that might not address the cause of the issue).

Techrunner

ASKER

I have configured the below command and so far no warning messages.

ip virtuak-reassemble max-reassemblies 512

But what could be the reason for those messages.

Thanks

Ernie Beek

Well, like I stated above (mtu settings). Also, when using IPSec, GRE, etc you can expect this.

thrigger

High CPU usage caused by the low max-reassemblies you set and also there is no hardware acceleration support for the 1921 routers.

Techrunner

ASKER

Thanks it's solved