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scionproto / scion

SCION Internet Architecture
https://scion.org
Apache License 2.0
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Host address padding #355

Closed kormat closed 8 years ago

kormat commented 9 years ago

Currently host addresses are not padded in the scion header, they're just appended to the common header, and all other headers are then appended to the host addresses. This makes for bad alignment. We need to decide on how to pad the addresses.

My proposal is we concatenate the src/dest host addresses, and then pad the result to an 8B boundary. Doing padding after each host address means that IPv6->IPv6 will have 8B of padding in the header, which is something that would be better to avoid.

taka-sasaki commented 9 years ago

Nice idea! Good alignment may improve the performance of High-speed router.

pszal commented 9 years ago

Why we need to pad that? In both cases (ipv4/6) concatenation of src and dst SCION addresses is multiplication of 8B. I.e., 2 * (ISD+AD+IPv4) gives 16B and 2 * (ISD+AD+IPv6) gives 40 B. We may consider to pad other addresses (if we want to use them), or in case of hybrid addressing (like IPv4 -> IPv6).

On 7 September 2015 at 17:34, taka-sasaki notifications@github.com wrote:

Nice idea! Good alignment may improve the performance of High-speed router.

— Reply to this email directly or view it on GitHub https://github.com/netsec-ethz/scion/issues/355#issuecomment-138326244.

kormat commented 9 years ago

An SVC host address is 6 bytes. And yes, hybrid addressing needs fixing.

kormat commented 8 years ago

This is fixed.