Nexus Line Cards Naming Convention

This post is a brief explaination about knowing the specification of Nexus series switches M and F series line modules ( or I/O modules) from its name
.
I am taking example of F-Series I/O module (N7K-F248XP-25) and similarly M series can also b read.
Example:
N7K-F2 48 X  P - 2  5 

Below is the explanation of each field and explained with other option you may see in different line cards:
N7k
is self explanatory, it indicates the type of chassis,
F2 
it is the series, family or generation of F series line cards. This one is 2nd generation, means F2 family. Similarly M1, M2, F3 and so on.
48
No. of ports on the card.

X   Or  F or C  or G 
G means ports are 1 Gig ports
X means 10 Gig ports
F means 40 Gig ports (Ex: N7K-F312FQ-25).
C indicates 100 G (Ex: N77-F312CK-26)

P  or S or  T or Q or Kor 2
it is interface type,
S means SFP
P means SFP+ .
T means RJ45(Ex: N7K-F248XT-25E)
Q means QSFP+(Ex: N7K-F312FQ-25) ,
K means Cisco CPAK( Ex: N77-F312CK-26)
2  means X2 (ex. N7K-M108X2-12L)

25 
Means FAB2 module required and 5 FAB2 module needs to be installed to run at full capacity.

Nexus 5548P vs 5548UP vs 5596UP Switch

I am often asked what is difference between Nexus 5548P and 5548UP switch? In this post i am going to explain the differences between these two and will also include 5596UP into the discussion.

First of all, all these 3 models are Nexus 5k Switches and basically 5500 series models.
"U" stands for "Unified" ports, so what does that "unified port" mean? Unified means a port is capable of running into either "Ethernet" or "FC" (Fibre Channel).

For those who are not aware of SAN protocols, i would like to inform you that term "Fibre" here does not mean the "Fiber" Media ( ie. copper vs fiber) which people refer in terms of cable, [ please note the difference in spelling, Fibre vs Fiber).

Fibre Channel or FC is a protocol stack in SAN, similar to what TCP/IP is to Networks. SAN switches run on FC protocol standards, not Ethernet or TCP/IP.(Just a highlevel overview)

So coming back to 5500 series models, all ports of 5548UP and 5596UP models of  Nexus 5k, can be used in ether Ethernet or FC mode,however, ports on 5548P do not work in FC mode. But the ****important thing to note is that this difference is valid for "In-built fixed" ports only******. That means, both 5548P and 5548UP switch comes with 32-port "in-built"or Fixed ports, plus one expansion module capable of 16 ports.

So, basicaly 5548P support Unified Port (Ethernet or native FC ) on the expansion module only,however, in 5548UP, all ports are unified ports.

5596UP comes with built-in 48 Ports, plus we can use  3 expansion slots for additional ports depending on our requirement.

That was the main difference, other differences are:
- 5548P and UP switch are 1 RU,however, 5596 is 2 RU switch
-Switching capacity of 5548 series are 960Gbps ,however, 5596 is 1.92 Tbps
-5548P only supports front-back airflow,however, 5548UP and 5596 supports both front-back and back-front.
-a Seperate Layer 3 Daughter card can also be ordered/used to get 160 Gbps of Layer 3 routing capability in 5548P and 5548UP switches, however, 5596UP can support L3 routing engine through an Expansion Module.

Basic understanding of OTV

Today i am going to help you understand Why we need OTV?

Lets say, we have 3 switches (A,B,C). Switch A is connectec to B and Switch B is connected to Switch C. and Switch A has 2 vlans created on it, vlan 10 and 20. What if we want the the vlan 10 and 20 to be extended to Switch C over Switch B, We will have to simply create vlan 10 and 20 on both switch B and C and allow both the vlans on trunks connecting the switches, right? and its simple!!

If you look at this pic, we have two Datacenters, DC1 and DC2 which are geographicaly far away from each other, lets say one in Newyork and another one in Los Angles and  there are some server which are there in both data centers,however, they sync their hearbeat over layer 2 only and doesnt work on layer 3. So,we have a requirment that we have to extend vlan 10 and 20 from DC1 to another data center, DC2!! You may call it Datacenter Interconnect (DCI).

can we do the same thing which we did to extend vlan from switch A to switch C in above example? Ofcourse Not!!, so what the are the solutions to achieve this?
Until OTV came into picture, we had few of the below options to achieve this:
-VPLS
-Dark Fiber (CWDM or DWDM)
-AToM
-L2TPv3

 

These are the services provided by Service Providers and they work on different mechanisms but basicaly what they do is, they provide you a layer 2 path between DC1 to DC2 similar to a trunk link between Switch A and Switch B. So what does that mean? If a broadcast is sent or a ARP request is sent, that will travel across the service provider to another data center in that VLAN? Ofcourse YES!! Your STP domain will also get extended over DCI. So, if a device in vlan 10 in DC1 is trying to communicate with another device which is also in DC1 but the ARP request will go all the way to DC2 switches on which that particular vlan is configured. 

So, to avoid such problems, Cisco introduced OTV  (Overlay Transport Virtualization) which is basicaly a DCI (data center interconnect) technology to be configured on Nexus Switches. Using OTV, we can extend Layer 2 between two or more datacenters over traditional L3 infrastructure provided by Service Provider, and we dont need a seperate L2 link for layer 2 extension and we will still be able to limit STP domain and unnecessary broadcast over WAN links.  It can overlay multiple VLAN with a simple design. Basically what it does is that, Datacenters will be able to advertise their MAC addresses to each other(its called
Mac in IP" routing) and a decision can be made on the basis of MAC addresses whether that MAC address is local or in another data center and based on that, frame can be forwarded or limited to a particular data center only. OTV uses a control protocol to map MAC address destinations to IP next hops that are reachable through the normal L3 network core.

So, in Cisco's language "OTV can be thought of as MAC routing in which the destination is a MAC address, the next hop is an IP address, and traffic is encapsulated in IP so it can simply be carried to its MAC routing next hop over the core IP network. Thus a flow between source and destination host MAC addresses is translated in the overlay into an IP flow between the source and destination IP addresses of the relevant edge devices. This process is called encapsulation rather than tunneling as the encapsulation is imposed dynamically and tunnels are not maintained"

How this is implemented, that i will show in another simplified post!!Thank you!!