98 lines
2.9 KiB
Plaintext
98 lines
2.9 KiB
Plaintext
Just some general thoughts that have occurred to me as I've started
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looking at stuff related to designing a network stack...
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These are in no particular order.
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General Jottings
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----------------
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- zero-copy is a laudible aim, but in reality single copy is probably
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as good as we're going to get to. Basically this means that we copy data
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into the stack at some point.
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- we should use a version of the mbuff's that the BSD stack uses with changes
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so we use them more efficiently for our stack.
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- probably need an rx and tx queue for frames.
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- we should reallt be dealing with frames as soon as we can in the stack,
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though we don't want to fragment earlier than we need to - what a quandry!
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- it should be possible to stack/reorder modules as needed. This would be cool
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if we could deal with input from other sources, e.g. data from a USB port
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to be fed into a ppp stack, onto an atm/ethernet frame module and upwards.
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Userland vs Kernel Land
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-----------------------
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This has been decided as follows...
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- initial stack will be userland
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- stack should be modular enough that it could be moved into kernel with
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little or no real work.
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Initial Protocols
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-----------------
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- ethernet/802.x encapsulation (rx only for 802.x)
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- slip (?)
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- ppp (?)
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- arp
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- ipv4
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- icmp (v4)
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- udp
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- tcp
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Extra's
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-------
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- appletalk ?
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- ipv6
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- icmpv6
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- ipv6 discovery (arp for v6)
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- atm encapsulation module?
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- usb interface (net stack to usb??)
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Stack Map
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=========
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So, how does this all fit together???
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[david: My ascii art is terrible, so hope this works out :)]
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=================
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= User apps = USERLAND
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=================
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========= ========= =========
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= UDP = = ICMP* = = TCP =
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========= ========= =========
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\ | /
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\ | /
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===============
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MBUF = IP (v4/v6) =
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===============
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-----------------------------
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=============== | =======
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BUFFER = Eth/802.x =----|---= ARP =
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=============== | =======
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----------------------------|-----
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=========== |
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= NIC IF = | KERNEL
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===========
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* ICMP is used as a placeholder for both ICMPv4 and ICMPv6, which are very
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different from each other in scope and usage.
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Basically every module only needs to be able to call the module that deal with the
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input/output of the protocol it find encapsulated, i.e. if IP finds a TCP packet
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it simply needs to be able to call tcp_input and pass the mbuf along. There is a
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requirement that each call to xxx_input gives the length of the header as they're
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variable in most protocols.
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This just starts to scratch the surface, but I hope gives more of an idea
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of what's been bouncing around in my head. :)
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