Re: [lwip-users] Xilinx Board LWIP UDP Packet Length limitation

[address@hidden]

I don't have experience with ethernet packets bigger than1514 bytes, but 
I think the main limitations are:
- netif->mtu (you have to set this when initializing the netif)
- TCP_MSS (as you already have discovered)
- IP fragmentation: either turn it off (define IP_FRAG to 0) or set 
IP_FRAG_MAX_MTU higher than its default (1500)

there may be more though...

Simon



Gary Olson wrote:
> Hi,
>
>   I am working with Xilinx EDK and LWIP I think it is version 1.2.   I 
> am able to use the uecho test to send UDP packets less that length 
> 1460 bytes or so. 
>
>  But when I try to increase the UDP Packet length to 2000 it fails.  
> My desire is to at least be able to send packets that are
>
> 2500 bytes in length.  This is because I am trying to send  a whole 
> packet of data with the length of one packet to be about 2020 bytes 
> maximum.
>
>  
>
>  
>
> I tried increasing the TCP_MSS value from 1460 to 3000 (in the lwip 
> software settings).  This did not make it work however.
>
>  
>
> Does anyone know what I can do to send larger packets using LWIP.
>
>  
>
> Thank You,
>
>   Gary Olson
>
>  
>
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