100G Ethernet

100Gbit/s Ethernet Router Test: Alcatel-Lucent

Initially, we designed our test program with core routers in mind. Since 2003 the Alcatel-Lucent 7750 Service Router (SR) has become the flagship product of the IP division and is no stranger to the industry, focusing primarily on edge deployments. Alcatel-Lucent chose the 7750 SR-12 for the tests, citing its versatile functionality, scalability and deployment models, which included everything from video contribution networks to having its place within Internet exchange points. As the name implies, the “service router” focuses on services with heavy edge functionality, but the router did not have any problems to fulfill the roles designed in some of the tests for the core of the network. Alcatel-Lucent also mentioned that they indeed see deployments of the product in core, aggregation, and edge network areas. A recent LRTV interview adds some details and gives a nice overview of Alcatel-Lucent's capabilities:

The 100Gbit/s architecture is of course just as much a question of the interface line card as it is of the chassis, if not more so. For the tests, Alcatel-Lucent used their 100Gig-capable version of their Integrated Media Module (IMM) cards -- one with a single 100GbE interface and one with 12 10GbE interfaces (oversubscribed). They explained that the same network processor is used in both the 100GbE IMM card and the 10GbE IMM card and both are 100Gbit/s ready. The code version running on the router throughout the tests was TiMOS-C-8.0.R9. We were told that operators who already have a 7750 SR-12 in their network can upgrade to 100GbE by only purchasing the 100GbE interface card and potentially also a new power supply. The optics used in this test were of the LR10 type, but Alcatel-Lucent explained this was based on availability and that they support LR4 CFPs in their 100GbE interface card as well.

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^Eagle^ 12/5/2012 | 4:59:20 PM
re: 100Gbit/s Ethernet Router Test: Alcatel-Lucent


The article stated that the 100GigE interface was an SR-10.  To my knowledge, this interface is a parallel interface with multiple 10G lanes.  Aggregated to 100G.  

Question: is this true?  That the "100G" side of the tests were actually multiple 10G physical lanes?

If so, how is this different than the other side of the test where it was acknowledged that the links were indeed multiple 10G lanes.

I realize SR-10 was used due to availability of interfaces from ALU suppliers.  And that the statement that the box also supports CFP LR4 interface, but that interface was not used in the tests.  Even though the SR10 is a "single" interface, it is actually multiple 10G lanes each over it's own multimode fiber. 

So, some clarification would be appreciated.  It seems to me that this entire test was basically multiple 10G lanes talking to multiple 10G lanes with one side aggregating the 10G lanes to make a "100G" port.  And the other side treating the 10G lanes as independent oversubscribed ports.

Still an impressive achievement from the box and the tests.  However, it seems clear the electrical IO was all still running at 10G.  

When will we see a 4x25G test?  


^Eagle^ 12/5/2012 | 4:59:12 PM
re: 100Gbit/s Ethernet Router Test: Alcatel-Lucent


Actually, I think the SR10 standard is also 20 strands of fiber.  Not 2.  As I read it anyway.  Willing to be corrected if I mis read the spec.

2 strands would require that this is single mode, and WDM muxed with 10 lambdas and a demux at the end.  if it is indeed WDM muxed then I mis-read the spec for SR10 and my mistake.



krishanguru143 12/5/2012 | 4:59:12 PM
re: 100Gbit/s Ethernet Router Test: Alcatel-Lucent

Yes, 40G and 100G all use 10G lanes.  The difference comes in the fact that you have 100G over a single connection; so two strands of fiber were used; one for tx and one for rx.  On the ten 10G links, 20 fiber strands were used; 10 for tx and 10 for rx.


In the real world, if you needed 100G between A and Z, would you rather use 2 strands or 20?  Sure 20 provides some redundancy over a failure, but you could also use 4 strands and get dual 100G rather than just 100G by using twenty strands.  Another issue that you run into, most equipment does have a limit to the number of aggregated pairs you can have as well as the number of ports in the aggregation.  You are usually limited to 8 per group, so in a single group the most you could get is 80G.  So in order to get 100G using individual 10G interfaces, you would have 10 totally separate paths.  The 100G is making it all look like a single interface as well as you are not using a lag to accomplish it.

Garci 12/5/2012 | 4:59:11 PM
re: 100Gbit/s Ethernet Router Test: Alcatel-Lucent

Actually, the interfaces used were LR-10. LR-10 are 10 lanes of 10Gig DWDMed into a single pair of fibers. Also, the electrical interface for the CFP is ALWAYS 10x10 Serdes. LR-4 optics using 4x25 Gbps lanes with DWDM muxing require a gearbox chip to convert the 10x10 into 4x25. Keep in mind though that these 10x10lanes (on the CFP-baseboard) interface are bit-level muxed and have no view on packets whatsoever. All interfaces, be them LR4, LR10 or SR10 allow the system to carry a single 100Gbps flow. There are no changes in the packet processor or data plane depending on the optics plugged into the card.

Hopes this helps clarify the issue.

furious_george 12/5/2012 | 4:59:10 PM
re: 100Gbit/s Ethernet Router Test: Alcatel-Lucent



100GBASE-SR10 is an IEEE standard defined interface for 100 Gigabit Ethernet.  I don't believe that the full clause is accessible for free online, but I'll point you to the presentation that was the basis for the eventual detailed specification for this PMD interface.


You are correct that the 100GE packet is striped across a physical bus of 10 optical lanes, however, the key point is that this is a 100GE packet.  The IEEE standardized the SR10 as a low cost 100GE variant for <100m connectivity.

Note I do not work for ALU, nor do I have any knowledge of their product -- I'm just chiming in on the IEEE standard.



sdmitriev 12/5/2012 | 4:59:10 PM
re: 100Gbit/s Ethernet Router Test: Alcatel-Lucent

There are only three types of CFPs available for 7750 right now: LR4 10km, OTU4 LR10 10km and LR10 4/10km (4km OTU4 or 10km 100GE). SR10, for sure, is typo.

^Eagle^ 12/5/2012 | 4:59:10 PM
re: 100Gbit/s Ethernet Router Test: Alcatel-Lucent


Thanks for the clarification regards LR-10.  I am very aware of the LR-10 spec.  If the article had stated that, I would never have made my post.  The article stated that it was an SR10 interface.

Hence the comments.

I am also quite aware of the 10x10 SerDes on CFP and the gearbox requirement for CFP to use 25G lanes.  I have been very involved with 10G, 40G, 100G (including 4x25 and all the various reaches in the standards and proposed standards) applications for many years.  

And I get it regards the packet processor, the data plane and bit level muxing.

if the original article, or the editor or the ALU company representative who should have reviewed it before publication for accuracy had caught it, and the article had not incorrectly stated SR10, this discussion would never have happened.

Garci, again, thanks for the clarification.


Houman0 12/5/2012 | 4:59:09 PM
re: 100Gbit/s Ethernet Router Test: Alcatel-Lucent

As correctly mentioned by a few others, the CFP modules used in this test were in fact LR10 variants (SR10 is a typo). Of course the LR4 variant is also supported and shipping. In either case for LR4 or LR10 there is an embedded WDM mux/demux function such that the 100G interface is served over only 2 fibers (TX & RX) and not 20.

krishanguru143 12/5/2012 | 4:59:09 PM
re: 100Gbit/s Ethernet Router Test: Alcatel-Lucent

Both cards that ALU has; single and dual port 100GigE all handle it with two fibers per port.


On the Ixia side going into the SR-12, they had 10 physical ports and each were not dependent on the the others; so no lag was used as that maxes out at 8 ports per lag group.  Each port used 2 fibers; so 20 in total.  On the 100GigE interface, it was two fibers going into a single port.  What they were showing with the test, the IMM could handle 100G of data.  So 100G into a single slot.  The FP3 that ALU is using can handle 400G of throughput.  So 4 port 100G cards will be available in the future.


With the card being run by the FP3, it won't matter if the lanes are 10G or 25G, the same physical silicon is handling it.  So the test of 4x25 will produce the same result.


They should have also mentioned what the forwarding rates were for the Multicast groups.

furious_george 12/5/2012 | 4:59:09 PM
re: 100Gbit/s Ethernet Router Test: Alcatel-Lucent

The "LR10" is not an IEEE standard.  It is a multi-source agreement based upon a proposal from Santur.  There are many pros & cons associated with it.  For a list of the pros, see http://www.10x10msa.org

I'm very pessimistic on it, but one never knows.



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