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New Member

C2610&cat1924 can't talk properly

Hi there,

I have more then 450 locations with Cisco 2610 & Catalyst 1924 couples in my WAN. But i saw that some of these couples have a problem: can not send packets larger than 1500 bytes properly, some of them are lost. The characteristics of this couples are shown below:

Cisco 2610

Part number 73-2839-08

Catalyst 1924

PCA Number: 73-3121-04

Model Number: WS-C1924-A

V8.01.02 : Standard Edition

I tried to download and update the Catalyst 1924 to V9.00.06 but there is no difference.

How can it be true? Is this a reality or am I dreaming?

Thank in advance,

Yasemin.

7 REPLIES
Bronze

Re: C2610&cat1924 can't talk properly

Yasemin,

What is the MTU on the ethernet interface of your 2610? The default is 1500, and this could explain your inability to send packets larger than 1500 bytes. Try increasing the MTU.

Mark

New Member

Re: C2610&cat1924 can't talk properly

Yes of course their deafult MTU is 1500 bytes, and 450 of my routers have the same default ethernet configuration. But only 10 couples with the above characteristics has this problem.

Yasemin.

Silver

Re: C2610&cat1924 can't talk properly

are you doing any GRE tunneling or running IPSec ?

New Member

Re: C2610&cat1924 can't talk properly

No, i'm not.

Silver

Re: C2610&cat1924 can't talk properly

I would do a traceroute then ping each hop with 1 ping & sweep the range from 1400 to 1600 with an interval of 100 to determine where the MTU is less than 1500.

Bronze

Re: C2610&cat1924 can't talk properly

This sounds like a path MTU problem. You cannot send packets larger than 1500 without fragmentation or path MTU. If a host (on a lan with a larger mtu than the intervening network can handle) uses PMTU it sends packets with the do not fragment bit set and the network device should send back an ICMP message so the host will try a smaller size. If the network device doesnt support PMTU it just drops the packet, hence lost data. Can you explain where the large packets are coming from? Is there a lan with a larger mtu or is the host preframenting the data?

New Member

Re: C2610&cat1924 can't talk properly

Yes this is a kind of MTU problem and the problem is over when mtu of the interface decreased to 1400. But i want to learn if there is a known problem with Cisco 2610 (Part number 73-2839-08 ) and Catalyst 1924 (PCA Number: 73-3121-04, Model Number: WS-C1924-A, V8.01.02 : Standard Edition). Because i don't have any problem with Cisco 2610 (Part number 73-2839-11, xxxxxxx-12, xxxxxxx13 ) and Catalyst 1924 (PCA Number: 73-3121-04, Model Number: WS-C1924-A, V8.00.xx : Standard Edition, and Enterprise Edition).

Large packets are coming from central office. Some screen shots of the application are saved on branch office's application server. They are sent to branch in night, but we saw that some of them could not be replaced. At the end of this research only 10 of these branches with -08 router and 8.01 switch has this problem. All the other 440 branches work properly.

Thanks.

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