大数据是否需要封装在多个MDL中发送

前段时间，我们已经解决如何发送自定义的网络数据。那么接下来要做的是，要是要发送的数据很大， 是否需要把数据拆分，然后封装在多个MDL中发送呢？由于NdisAllocateMDL函数只能分配一个MDL，所以倘若需要多个MDL的话，那么就要解决如何串联多个MDL的问题。现在所掌握的资料，如果通过预分配调用NdisALlocateNetBufferAndNetbufferList的方式构建NBL的话，那么串连两个MDL的可查资料为：

NDIS_MDL_LINKAGE(FirstMdl) = SecondMdl;

 需要其他的比如设置dataLength这些应该不要设置了吧。但如果是后来增加新的一个MDL，就需要设置哪些数据参数了。

 

话又说回来了，如果我统统把所有的数据都放在一个MDL中，会如何呢？据我所知，如果在发送网络数据的时候，过大的数据也自动会被切成多个小包发送。这个网络上的一问一答(http://www.eggheadcafe.com/software/aspnet/33553113/ndisallocatemdl.aspx)：

问题：

写道

Does NdisAllocate Mdl return a single MDL or a chain of MDL's based on the
size of the data buffer being described and physical page size? I looked at
MSDN but it does not say anything about this.

I am guessing that if say I have a 15K buffer on a system with 4k page size
then I will need 4 MDLs to describe the buffer and these MDLs will be chained
and the chain is what is returned from the call to NdisAllocateMdl. Is this
statement correct?

Thanks.

 回答是：

写道

As long as the buffer is "virtually contiguous" (i.e. one virtual address
describes the entire 15K buffer) then you only need one MDL to describe it.
You don't need multiple MDLs just because the buffer may be "physically
fragmented”.


The fact that the memory might span 5 pages is reflected in the pfn array at
the bottom of the MDL (after the header).

 所以我想，不妨先试试看~当然分两个MDL发，肯定也是可以的。只不过我还没有想到如何串联它们俩。https://www.osronline.com/cf.cfm?PageURL=showThread.CFM?link=134437

 

二：还有一个问题，如何区分多个Filter实例。我们知道每个Filter instance都绑定在对应的网卡上，包含虚拟网卡。那么如何区分哪个filter实例是对应的某个网卡呢？因为倘若要指定某张网卡执行操作，那么必须知道其对应的那个filter实例。目前可以利用的资源就是pFilter中的一个参数：

BaseMiniportInstanceName

A pointer to a an NDIS_STRING type value that contains a counted Unicode string. This string specifies the friendly name of the interface for the base miniport adapter. For Windows 2000 and later versions, NDIS defines the NDIS_STRING type as a UNICODE_STRING type.

BaseMiniportName

The name of the base miniport adapter.

FilterModuleGuidName

The GUID name of the filter module that NDIS is attaching.

至于哪个可以用，还需测试~