nanog mailing list archives
Re: Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue)
From: Alia Atlas <akatlas () gmail com>
Date: Fri, 2 Dec 2016 11:16:36 -0500
On Fri, Dec 2, 2016 at 11:07 AM, Christopher Morrow <morrowc.lists () gmail com
wrote:
On Fri, Dec 2, 2016 at 11:02 AM, Simon Lockhart <simon () slimey org> wrote:On Fri Dec 02, 2016 at 10:29:56AM -0500, Christopher Morrow wrote:you'd think standard testing of traffic through the asic path somewhere between 'let's design an asic!' and 'here's your board ms customer!'wouldhave found this sort of thing, no? or does testing only use 1 macaddressever?Well, it's actually payload, rather than src/dst MAC used for forwarding, so there's quite a few more combinations to look for... 2^(8*9216) is quite a lot of different packets to test through the forwarding path... But, wait, that assumes every bit combination for 9216 byte packets, but the packet might be shorter than that... So multiply that by(9216-64).but most/all forwarding asics (aside from perhaps extreme's?) only deal with the first N bits in the header (128 or so..) so... not quite as many right?
This sounds related to the well-known (at least 10+ years) issues around guessing the type of IP packet by looking at the first nibble of the encapsulated packet. Take a quick look at RFC 7325, section 2.4.5.1 bullet 6. This is what using the pseudo-wire code-word is meant to protect against. I don't know if that's an option for networks using this. Regards, Alia
Anyone want to work out how many years that'd take to test, even at 100G? Simon
Current thread:
- Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue) Job Snijders (Dec 02)
- Re: Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue) Christopher Morrow (Dec 02)
- Re: Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue) Simon Lockhart (Dec 02)
- Re: Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue) Christopher Morrow (Dec 02)
- Re: Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue) Christopher Morrow (Dec 02)
- Re: Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue) Alia Atlas (Dec 02)
- Re: Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue) Saku Ytti (Dec 02)
- Re: Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue) Simon Lockhart (Dec 02)
- Re: Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue) Job Snijders (Dec 06)
- Re: Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue) Mike Jones (Dec 06)
- Re: Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue) Alexandru Suciu via NANOG (Dec 07)
- Re: Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue) Job Snijders (Dec 07)
- Re: Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue) Christopher Morrow (Dec 02)
- Re: Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue) Saku Ytti (Dec 06)