How to make the sales department finish reading a boring engineer letter about Cisco transceivers?

On duty, I often put in a copy of many letters in our company. It would seem that letters between engineers and sales managers should be mostly technical and slightly interesting. But engineers — creative people and even ordinary letters try to make so that at the other end of the correspondence not only technical knowledge but also a little bit of good mood is added. I would like to share with Habr one of these letters. At a minimum, it can be useful for the community when selecting transceivers for Cisco Nexus switches. The style of the letter is fully preserved.

---

Hello, my dear manager!
By popular demand today, I will tell you about the balloons of the transceivers that enter and exit can be connected to the Nexus 3524X switch in the pot .
')


Tsiski has a pair of documents by which you can determine which transceivers are suitable for a particular device and what kind of transceivers are:

1. 1 GB SPF transceivers. Compatibility Matrix Description of transceivers, it is the same date .
2. 10 GB SFP + transceivers. Compatibility Matrix Description of transceivers, it is the same date .
3. 40 GB QSFP + transceivers. Compatibility Matrix Description of transceivers, it is the same date .

In the 3524X there are no QSFP connectors, so the third point would seem to be irrelevant for us. Moreover, in Compatibility Matrix for 40GB QSPF +, in principle, there is no N3K-C3524P-10GX. But we can all connect it early to Tsisk, which has a QSFP + port (of course, provided that this type of cable is supported by this tsiska). This is done using Twinax cable, similar to octopus, but with 4 tentacles:



That is, in fact, we spend 4 ports of 10GB SFP + of our nexus on connecting to another 40 GB QSPF +.

I draw your attention that our pot does not support FCoE in principle, therefore only 10GB SPF + S-Class transceivers are relevant, which will save both money and time for explaining the difference between S and not S.

So, if you run through these documents, then we get the following general picture of the balloons transceivers. Remove the extra 10GB transceivers and add our four-piece:

Speed	Part Number	Fiber type		Distance 1 (m)	Price GPL (USD)	Software version on the switch (minimum)
		Single mode (SM)	Multimode (MM)
1 GB SFP	GLC-SX-MMD 2	-	+	220, 275, 500, 550, 1 000	525.00	NX-OS 6.0 (3) A6 (1)
	GLC-LH-SMD	+	+	10,000 for SM 550 for MM	1,044.75
	GLC-TE	on copper	on copper	100	414.75
	GLC-EX-SMD	+	-	40,000	2,094.75
	GLC-ZX-SMD	+	-	70 000 3	4,194.75
10 GB SPF +	SFP-10G-SR-S 4	-	+	26, 33, 66, 82, 300, 400	682.50	NX-OS 6.0 (2) A6 (8)
	SFP-10G-LR-S	+	-	10,000	1,995.00
	SFP-10G-ER-S	+	-	40 000 5	8,295.00
	SFP-10G-ZR-S	+	-	80,000 5	11,445.00
	Twinax / AOC 6 cables
	Part Number	Active / Passive 7		Distance (m)	Price GPL (USD)	Software version on the switch (minimum)
		Active	Passive
	SFP-H10GB-CU1M	-	+	one	105.00	NX-OS 6.0 (2) A6 (1)
	SFP-H10GB-CU1-5M	-	+	1.5
	SFP-H10GB-CU2M	-	+	2
	SFP-H10GB-CU2-5M	-	+	2.5
	SFP-H10GB-CU3M	-	+	3
	SFP-H10GB-CU5M	-	+	five	157.50
	SFP-H10GB-ACU7M	+	-	7	378.00
	SFP-H10GB-ACU10M	+	-	ten	430.50
	SFP-10G-AOC1M	+	-	one	220.50
	SFP-10G-AOC2M	+	-	2
	SFP-10G-AOC3M	+	-	3
	SFP-10G-AOC5M	+	-	five	273.00
	SFP-10G-AOC7M	+	-	7
40 GB QSFP +	Twinax QSFP to Four SFP + (Copper Breakout Cables) 8
	Part Number		Distance (m)		Price GPL (USD)
	QSFP-4SFP10G-CU1M		one		472.50
	QSFP-4SFP10G-CU3M		3
	QSFP-4SFP10G-CU5M		five		708.75

1 - Where several parameters are indicated, means that the distance depends on the class of optical cable - FDDI, OM1, 400/400, OM2, OM3, OM4 (relevant only for 10 GB).

2 - The letter “D” means DOM - Digital Optical Monitoring, monitoring the status of the transceiver (voltage, temperature, power and signal level, etc.).

3 - The value is not guaranteed, it depends, to a large extent, on the link losses.

4 - The letter "S" means S-Class transceiver. It features no support for FCoE (Fiber Channel over Ethernet). FCoE is mainly used to connect to a SAN. For most of the tasks of our customers, S-Class is more than relevant.

5 - When used at distances less than 20 km, it is necessary to use an attenuator ( what is this at all ). In fairness, the use of an attenuator is relevant for cases where the actual distance between the devices is substantially less than the maximum possible distance of the transceivers.

6 - Active Optical Cables - active (more on this below) optical cables with already sealed transceivers at both ends (everything is exactly the same as twinax, except that they are only active and optical).

7 - For Twinax, there is a division into active and passive. The difference is that in active Twinax (as in all AOC) additional components are used (in the connector itself) to increase the signal. This allows active transceivers to operate at greater distances than passive ones. There is no visual difference (except for the wire length) between active and passive Twinax.

8 - Twinax Breakout Cable is a branched Twinax cable, which has a QSFP + transceiver on one side for connecting to the corresponding port, and on the other side 4 transceivers for 10GB SFP + connectors. To N3K-C3524P-10GX connect exactly 4 branched wires to 10GB SFP +.

PS Twinax - copper, AOC - optical, this is their main difference, in addition to the fact that AOC is only active.
PPS The table may not indicate all transceivers that are in the compatibility matrix. This is due to the fact that some of them have already gone to EOS or will go there soon.

In the case of Twinax, we don’t forget that the same partnumber must be supported by both devices that are connected by this Twinax.

My dear manager, we know that there is a rumor among you about the existence of unique (!), Vendor independent (!!) super cheap (!!!) transceivers. As well as the rumor that Twinax is excellent for servers and switches from other vendors. In most cases, such rumors are spread by satisfied customers who have managed to deceive the system. BUT. We cannot give any guarantees or recommendations on the use of third-party transceivers with Cisco or Twinax equipment with other vendors' equipment. At least because the vendor itself, in most cases, will not give such guarantees and recommendations. In our professional activities, we cannot rely on the words and personal practice of Evdokim from Horns and Hoofs LLC or the user superCiscovoda from, even the official, Cisco forum. There are a lot of nuances in transceivers that can affect its operation. Even a software update device can lead to the fact that a non-native, long-working, transceiver suddenly stopped working. In most of these situations, it is worthwhile to tell the customer that he is cool, how lucky and super, that everything works.

And one more important point: the Cisco 10 GB transceiver does not exist on copper! Anyway, bye .

That's all. Thank you very much for reading to the end, and I hope you find this useful. If you have any questions, you know where to find me.



Yours, your engineer.

---

The author of the letter is a system engineer of our company, hiding under the name epicf4il .