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16 votes

Serialization and serialization times in 40G/10G and 100G/25G Ethernet

You're overthinking. The number of lanes used doesn't really matter. Whether you transport 50 Gbit/s over 1, 2, or 5 lanes, the serialization delay is 20 ps/bit. So, you'd get 5 bits every 100 ps, ...
Zac67's user avatar
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14 votes
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Serialization and serialization times in 40G/10G and 100G/25G Ethernet

The part that does the division to multiple lanes is called Physical Coding Sublayer in IEEE 802.3ba standard. This presentation by Gary Nicholl gives a good overview of it. The short explanation is ...
jpa's user avatar
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8 votes
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Must 40/100G uplink ports on a 10G switch be connected to another switch?

That switch uses (Q)SFP+ ports which are essentially PHYless. You need to either use matching PHY type transceivers on both the switch and the host ports (e.g. 10GBASE-SR or 40GBASE-SR4) or direct-...
Zac67's user avatar
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5 votes
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Can I use a 40G transceiver in a QSFP56 NIC to connect to a 10G transceiver/switch if the NIC supports 10G speeds?

The only way you'd be able to keep using the same 40G QSFP is to get a 40G-SR4 and break it out to 4x10GE coming from the NIC and then connect one of those 10G's to your 4500. Once you have a switch ...
rnxrx's user avatar
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3 votes

QSFP BiDi 40GB with two LC-LC

Hi and welcome to Network Engineering. Probably, you won't be able to specify nor auto-detect "speed 20000" on the QSFP+ switchport, and as long as not all 4 lanes of the PHY return an "up" signal ...
Marc 'netztier' Luethi's user avatar

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