Hello Operator?
Before we jump into the switches we use in our day to day lives at the office. I would like to take you back again to a time when we had telephone operators who would 'switch' our calls for us. These operators had the job of picking up any calls that would come in. You would tell them who you are trying to reach and they would connect your line by physically moving a cable from one port on the switchboard to the port of the person you are calling. Their phone will ring and now you are able to have a telephone conversation.
I want you to remember the concept of the operator having to take a physical wire and connect it to a different port as we will be making our own switches do this for us in a similar fashion automatically for us as we start discussing the network switch next.
The Network Switch
Mac OS / Clang Windows / MSVC WebAssembly / Emscripten Interpreter / Cling IDEs Basic Syntax Basic Syntax Input / Output Input / Output Build script Hello World Input Output Format Tabulate Control flow Control flow Build script. So here we'll make a command line operating system. As we saw the previous code, the code just writes some text on screen via Console.WriteLine function. Now we will write a OS where the user gives the input and the computer processes it. So, lets make a code which prints Hello User! On January 5, 2009, Google released a beta version of Picasa for Mac (Intel-based Macs only). Also, a plugin is available for iPhoto to upload to the Picasa Web Albums hosting service. There is also a standalone Picasa Web Albums uploading tools for OS X 10.4 or later. The Picasa for Mac is a Google Labs release.
Now what is a switch and what does it do? Similar to the call operators it is a central point where cabling goes into (physical) in order to receive frames or 'Signals' that are then switched out of the correct ports, switches are an evolution of networking technology which is a great advancement from things such as hubs as well as bridges, the switch is smart enough to switch traffic specifically on a port basis where only the port where the recipient is connected to will receive the frames and the sender will receive any return traffic back, things such as hubs would broadcast the traffic out of all the ports causing problems such as increased network traffic as well as major security concerns as everyone would receive your data.
The process a switch follows is quite straight forward and I will quickly list the details here while we reference the OSI Model as well.
1) The switch will receive a frame on one of its ports and this frame will contain a destination and source MAC-address.
2)The switch will put an entry in its CAM Table or MAC-Address table of which port the frame came from and it will do a lookup against the MAC-Address table if the destination MAC-Address has been learned.
3)If the destination MAC-Address has not yet been learned the switch will send a broadcast message out (an ARP) of all of its ports to try and learn the MAC-Adress.
4)If the destination MAC-Address has been learned the frame will be sent out of the port where the MAC-Address has been learned if no MAC-Address is learned the frame will be dropped.
That is the base function the switch has, it is there to learn MAC-Addresses and switch the traffic in and out of ports, we also have additional features to talk about such as VLANs where the switch can partition some of its ports into different broadcast domains, meaning if the switch receives a frame with a VLAN tag added to the header it will only forward the frame out ports that also have this same VLAN tag configured to it.
Media Access Control Address
A Media Access Control Address or for short a MAC-ADDRESS. This is a physical 48bit address that is burned into each and every NIC when manufactured. These addresses will contain information on the OUI (Organizational Unique Identifier) as well as NIC specific information, think of the OUI as the vendor where Cisco, Juniper or Mikrotik devices will have their own unique 24bit address added to the front of each MAC-Address which serves as proof that this hardware belongs to this vendor.
Think of the MAC-ADDRESS as the IP address that switches use to communicate and that switches transfer frames by sending them out of a port for a specific MAC-ADDRESS, this is all pure Layer 2 communication.
Virtual Local-Area-Network (VLANs)
If you're new to networking then the idea of VLANs might confuse you a little however, I will do my best to explain what a VLAN is in the easiest terms possible. VLANs allow us a way to assign our switch ports into different broadcast domains. VLANs also follow a standard called 802.1Q. Goin mac os. If you recall I mentioned that a switch will send a broadcast message whenever it is doing a lookup for a MAC-ADDRESS. When we start adding VLANs to the Layer 2 equation the lookup will only be done on the broadcast domain that the frame was received so if you have a Laptop in VLAN1 trying to send a frame, the switch will receive the frame and only send the frame out of ports that also have VLAN1 assigned to it, the machines in VLAN2 will not receive any broadcast messages and no frames will be passed between machines in different VLANs.
This is useful for segmenting your network and could potentially also be a security requirement for the company you work for, where machines in your finance department may only see other finance department machines. Another use for this would be to split up customer networks as well, you could potentially use the same switch for many different customers and none of their frames will be exchanged with each-other due to how VLANs function.
Conclusion
You have now learned how switches work in our day to day lives and how layer 2 frames are passed between ports as well as what a Mac-Address is and what VLANs are, this is a very important fundamental for any network engineer as this plays a big part in your daily work, the bigger the networks you support the more VLANs you will start seeing and the more switches you will be supporting. I hope this has been informational for you and that you have learned something new.
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Hungry for more?
Why not check out the follow-up post on routers and routing
https://thenetworkberg.com/routers-and-routing to get more insight on how routing works or check out the previous article for a refresher on host-to-host communication on what a network is
https://thenetworkberg.com/networking-basics
'Miss Susie had a steamboat', also known as 'Hello Operator',[1] 'Miss Suzy', 'Miss Lucy', and many other names,[8] is the name of an American schoolyard rhyme in which each verse leads up to a rude word or profanity which is revealed in the next verse as part of an innocuous word or phrase. Originally used as a jump-rope rhyme, it is now more often sung alone or as part of a clapping game.[9] Hand signs sometimes accompany the song, such as pulling on the bell in the first verse or making a phone gesture in the second.
This song is sometimes combined or confused with 'Miss Lucy had a baby', which is sung to the same tune and also served as a jump-rope song. That song developed from verses of much older (and cruder) songs which were most commonly known as 'Bang Bang Rosie' in Britain, 'Bang Away Lulu' in Appalachia,[10] and 'My Lula Gal' in the West.[11] The variants including a woman with an alligator purse urging the baby's mother to vote have been seen as a reference to Susan B. Anthony, an American suffragette and wife,[12] and may be responsible for the steamboat owner's most common name today.
Structure[edit]
The rhyme is arranged in quatrains, with an A-B-C-B rhyme scheme. The rhyme is organized by its meter, a sprung rhythm in trimeter.[13]Accentual verse (including sprung rhythm) is a common form in English folk verse, including nursery rhymes and jump-rope rhymes. The rhyme approaches taboo words, only to cut them off and modify them with an enjambment. It shares much of the same melody as the 1937 'The Merry-Go-Round Broke Down' used by Warner Bros. as the theme to their Looney Tunes cartoons.[14]
History[edit]
The song has developed many variations over an extended period, as is common for such rhymes.[15] Even 21st-century versions, however, typically preserve long-outdated references to the dangerousness of 19th-century steamers and to the need for a switchboard operator to manually connect a telephone call.
The earliest recorded version—about a girl named Mary—appears among the vaudeville jokes collected by Ed Lowry during his career in the 1910s, '20s, and '30s,[2] although versions about Fulton (popularly credited with the invention of the steamboat[16]) and Lulu (the star of 'Bang Bang Lulu') may record older traditions. The Lulu tradition—including 'Miss Lucy had a baby'—already record enjambeddouble entendres during the World Wars, but the first version of this song known to have done so—versions about Fulton and a girl named Helen—date to the 1950s.[17]
Later versions developed by embellishment: adding, removing, and adjusting stanzas involving kissing, boys in bathrooms, a little black boy, bras, King Arthur, questions and lies,[18][unreliable source?] German spies,[5] raving aunts,[5] and so forth. While the initial stanzas were fairly stable by the late 20th century, the folklorist Josepha Sherman noted that two unrelated children in 1990s New York took the change from 'Miss Lucy' to 'Ms. Lucy' for granted.[19] An adaptation—'Miss Lucy had some leeches'—has been recorded by Emilie Autumn[20] and another—'Mrs. Landers was a health nut'—featured in the South Park episode 'Something You Can Do with Your Finger'.[21][22]
Lyrics[edit]
Hello Operator. Mac Os Catalina
This song is sometimes combined or confused with 'Miss Lucy had a baby', which is sung to the same tune and also served as a jump-rope song. That song developed from verses of much older (and cruder) songs which were most commonly known as 'Bang Bang Rosie' in Britain, 'Bang Away Lulu' in Appalachia,[10] and 'My Lula Gal' in the West.[11] The variants including a woman with an alligator purse urging the baby's mother to vote have been seen as a reference to Susan B. Anthony, an American suffragette and wife,[12] and may be responsible for the steamboat owner's most common name today.
Structure[edit]
The rhyme is arranged in quatrains, with an A-B-C-B rhyme scheme. The rhyme is organized by its meter, a sprung rhythm in trimeter.[13]Accentual verse (including sprung rhythm) is a common form in English folk verse, including nursery rhymes and jump-rope rhymes. The rhyme approaches taboo words, only to cut them off and modify them with an enjambment. It shares much of the same melody as the 1937 'The Merry-Go-Round Broke Down' used by Warner Bros. as the theme to their Looney Tunes cartoons.[14]
History[edit]
The song has developed many variations over an extended period, as is common for such rhymes.[15] Even 21st-century versions, however, typically preserve long-outdated references to the dangerousness of 19th-century steamers and to the need for a switchboard operator to manually connect a telephone call.
The earliest recorded version—about a girl named Mary—appears among the vaudeville jokes collected by Ed Lowry during his career in the 1910s, '20s, and '30s,[2] although versions about Fulton (popularly credited with the invention of the steamboat[16]) and Lulu (the star of 'Bang Bang Lulu') may record older traditions. The Lulu tradition—including 'Miss Lucy had a baby'—already record enjambeddouble entendres during the World Wars, but the first version of this song known to have done so—versions about Fulton and a girl named Helen—date to the 1950s.[17]
Later versions developed by embellishment: adding, removing, and adjusting stanzas involving kissing, boys in bathrooms, a little black boy, bras, King Arthur, questions and lies,[18][unreliable source?] German spies,[5] raving aunts,[5] and so forth. While the initial stanzas were fairly stable by the late 20th century, the folklorist Josepha Sherman noted that two unrelated children in 1990s New York took the change from 'Miss Lucy' to 'Ms. Lucy' for granted.[19] An adaptation—'Miss Lucy had some leeches'—has been recorded by Emilie Autumn[20] and another—'Mrs. Landers was a health nut'—featured in the South Park episode 'Something You Can Do with Your Finger'.[21][22]
Lyrics[edit]
Hello Operator. Mac Os Catalina
Numerous versions exist, varying across time and regionally. One version is as follows:
Miss Susie had a steamboat,
The steamboat had a bell,
Miss Susie went to heaven,
The steamboat went to..
Hello Operator,
Please dial Number 9,
And if you disconnect me,
I'll kick you from..
Behind the 'frigerator,
There lay a piece of glass,
Miss Susie sat upon it,
And cut her little..
Ask me no more questions,
I'll tell you no more lies,
The boys are in the bathroom,
Zipping down their..
Flies are in the backyard,
The bees are in the park,
Miss Susie and her boyfriend
Are kissing in the D-A-R-K
Dark, dark, dark
Another version, from the early 1900s, begins as follows:[17]
Mary had a steamboat
The steamboat had a bell
Mary went to Heaven
And the steamboat went Toot Toot.[2][3]
See also[edit]
- 'Bang Bang Lulu'
- 'K-I-S-S-I-N-G'
- 'Miss Lucy had a baby'
References[edit]
- ^Mayfield, Josh. 'Hello Operator' at Inky's Linkies. 3 Apr 2004. Accessed 13 Jan 2014.
- ^ abcLevitt, Paul. Vaudeville Humor: The Collected Jokes, Routines, and Skits of Ed Lowry, p. 125. SIU Press (Carbondale), 2002. Accessed 12 Jan 2014.
- ^ ab'Tuyere Blasts'. Iowa Transit. October 1924.
- ^Yannucci, Lisa. 'When Lucy Had a Steam Boat' at Mama Lisa's World: Children's Songs and Rhymes from Around the World. 2014. Accessed 12 Jan 2014. Ms Yannucci credited her version as from Long Island in the 1970s.
- ^ abcBohren, Django. 'Lulu had a steamboat' at Milk Milk Lemonade. 27 Sept 2010. Accessed 13 Jan 2014.
- ^Crowley, John. Endless Things: A Part of Ægypt, pp. 428 ff. Small Beer Press (Northampton), 2007. Accessed 14 Jan 2014.
- ^Schultz, Emily. Joyland, [books.google.com.hk/books?id=A_d0uAikdR4C&pg=PA82 p. 82]. ECW Press (Toronto), 2006. Accessed 14 Jan 2014.
- ^Including Mary,[2]'Oh, it ain't—',[3] 'When Lucy had a steamboat',[4] 'Lulu had a steamboat',[5]Miss Sophie,[6] and Miss Molly.[7]
- ^Powell, Azizi. 'Similarities & Differences between 'Bang Bang Lulu' & 'Miss Lucy Had a Steamboat' at Pancocojams. 16 Oct 2013. Accessed 13 Jan 2014.
- ^Cray, Ed. The Erotic Muse: American Bawdy Songs 2nd ed., p. 173 ff.UIP (Champaign), 1999. Accessed 13 Jan 2014.
- ^Logsdon, Guy. The Whorehouse Bells Are Ringing and Other Songs Cowboys Sing, pp. 154 ff. 1995 reprint of UIP (Champaign), 1989. Accessed 13 Jan 2014. (NB: Logsdon's versions are set to the separate tune of the bluegrass traditional 'Roll in My Sweet Baby's Arms'.)
- ^Hollihan, Kerrie. Rightfully Ours: How Women Won the Vote, p. 78. Chicago Review Press (Chicago), 2012. Accessed 13 Jan 2014.
- ^Henninger, Jessie. 'Miss Susie Had a Steamboat: I. Structure' at The Raveled Sleeve. 29 Nov 2008. Accessed 13 Jan 2014.
- ^Smith, Ronald. Comedy on Record: the Complete Critical Discography, p. 634. Garland Publishing, 1988.
- ^Henninger, Jessie. 'Miss Susie Had a Steamboat: II. Evolution' at The Raveled Sleeve. 29 Nov 2008. Accessed 13 Jan 2014.
- ^Swede, George. The Steam Tug, p. 17. Xlibris, 2010. Accessed 14 Jan 2014.[self-published source]
- ^ abHenninger, Jessie. 'Miss Susie Had a Steamboat: V. Versions of the Rhyme Used in This Essay' at The Raveled Sleeve. 29 Nov 2008. Accessed 12 Jan 2014.[self-published source]
- ^The Mudcat Cafe. 'Origins: Ask Me No Questions rhymes' often where the lyrics cut to the same word, only in a different context. Apr 2006. Accessed 13 Jan 2014.
- ^Sherman, Josepha. 'Gopher Guts and Army Trucks: The Modern Evolution of Children's Folk Rhymes' in Children's Folklore Review, Vol. 21, No. 2 (Spring 1999). Accessed 12 Jan 2014.
- ^Emilie Autumn. 'Miss Lucy had some leeches' hosted at MetroLyrics. 2007.
- ^South Park. 'Something You Can Do with Your Finger' at South Park Studios. 2010. Accessed 14 Jan 2014.
- ^South Park. '[[:q:South Park/Season 4#Something You Can Do with Your Finger [4.8]|Something You Can Do with Your Finger]]' at Wikiquote. 2010. Accessed 14 Jan 2014.
External links[edit]
Mac Os Download
- 'Miss Susie' at TV Tropes
Hello Operator. Mac Os Download
