5 ms·

One of the interesting points about SCION is that it achieves today's required forwarding performance on commodity hardware. No more expensive and inefficient T

by _hl_ 5y ago

One of the interesting points about SCION is that it achieves today's required forwarding performance on commodity hardware. No more expensive and inefficient TCAMs, no more limits to scalability. This, among other features of SCION, provides an economic incentive for ISPs and organizations to switch to SCION eventually.

wmf 5y ago
How does that work? I'm not aware of any ASICs that understand SCION packet headers.
- kilburn 5y ago
  You are thinking about decoding, validating and forwarding a packet. I'm not a networking guy, so take the following with a grain of salt. Even without ASICs the read/decode/forward part is apparently not a big deal: you can easily saturate multi-gigabit connections with cheap cpus today. But only if you don't have to make complicated routing decisions (i.e.: select the most appropriate "next hop" for each packet). SCION pushes these decisions to the senders. When a sender sends a packet, that packet already contains the route it _has_ to follow. ISP routes are then dumb forwarders whose only job entails: 1. Ensuring the packet is valid (including a cryptography check for the route information). While this may seem expensive, note that pretty much all general-purpose cpus today include specific hardware to deal with this. 2. Forwarding it according to what the packet says Of course, this implies that there needs to be a "control layer" that allows end hosts to construct these routes for each packet. However, that control layer is similar to a DNS system, meaning that while not trivial it can use a hierarchical, heavily-cached approach and shouldn't be too challenging to scale.
  - wmf 5y ago
    An ASIC router does something like 10 Tbps for $10K while a software router is closer to 1 Tbps for $50K; the limit is I/O and memory bandwidth, so simplifying forwarding won't increase performance. And ISPs need multi-Tbps throughput for backbones (which is where SCION would be used).
  - dariusj18 5y ago
    > that packet already contains the route it _has_ to follow That sounds eminently abusable.

by _hl_ 5y ago

wmf 5y ago

How does that work? I'm not aware of any ASICs that understand SCION packet headers.

kilburn 5y ago
You are thinking about decoding, validating and forwarding a packet. I'm not a networking guy, so take the following with a grain of salt. Even without ASICs the read/decode/forward part is apparently not a big deal: you can easily saturate multi-gigabit connections with cheap cpus today. But only if you don't have to make complicated routing decisions (i.e.: select the most appropriate "next hop" for each packet). SCION pushes these decisions to the senders. When a sender sends a packet, that packet already contains the route it _has_ to follow. ISP routes are then dumb forwarders whose only job entails: 1. Ensuring the packet is valid (including a cryptography check for the route information). While this may seem expensive, note that pretty much all general-purpose cpus today include specific hardware to deal with this. 2. Forwarding it according to what the packet says Of course, this implies that there needs to be a "control layer" that allows end hosts to construct these routes for each packet. However, that control layer is similar to a DNS system, meaning that while not trivial it can use a hierarchical, heavily-cached approach and shouldn't be too challenging to scale.
- wmf 5y ago
  An ASIC router does something like 10 Tbps for $10K while a software router is closer to 1 Tbps for $50K; the limit is I/O and memory bandwidth, so simplifying forwarding won't increase performance. And ISPs need multi-Tbps throughput for backbones (which is where SCION would be used).
- dariusj18 5y ago
  > that packet already contains the route it _has_ to follow That sounds eminently abusable.