VLAN confusion
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For your own learning, try working backwards. Where in a switch do you perceive bottlenecks or performances issues? See if you can figure out what you are picturing, maybe there is a misconception that we can address.
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@scottalanmiller said in VLAN confusion:
Think of a switch like a big open parking lot. You can enter from dozesn or different locations and exit at any of dozens of locations. You are a packet, obviously. The parking lot is huge and there is enough room for everyone to get to where they need to go. Each connection is unique, from point to point, the only points of congestion come at the driveway, if a single driveway wants to send out too many cars at once or take too many in.
A simple switch, like a 24 port GigE switch, will often have a 40Gb/s backplane. That means that even if every port on the switch is at full capacity, it can't saturate the backplane. There is no capacity advantage by splitting up the traffic further, the switch is already handling it all at full speed. The ports are the bottlenecks, not the switch.
Good analogy, and I think I've gotten this concept more fully as of late. One of the terms I hadn't heard of before starting my job was the "backplane" word. I'm still not 100% certain on what it means, but I assume it's just the connecting board that all circuits pass through.. like a backbone or something.
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@dave247 said in VLAN confusion:
@scottalanmiller said in VLAN confusion:
Think of a switch like a big open parking lot. You can enter from dozesn or different locations and exit at any of dozens of locations. You are a packet, obviously. The parking lot is huge and there is enough room for everyone to get to where they need to go. Each connection is unique, from point to point, the only points of congestion come at the driveway, if a single driveway wants to send out too many cars at once or take too many in.
A simple switch, like a 24 port GigE switch, will often have a 40Gb/s backplane. That means that even if every port on the switch is at full capacity, it can't saturate the backplane. There is no capacity advantage by splitting up the traffic further, the switch is already handling it all at full speed. The ports are the bottlenecks, not the switch.
Good analogy, and I think I've gotten this concept more fully as of late. One of the terms I hadn't heard of before starting my job was the "backplane" word. I'm still not 100% certain on what it means, but I assume it's just the connecting board that all circuits pass through.. like a backbone or something.
In the case of a switch, the backplane is actually a bus, but one with a lot of logic associated with it. It's so fast, that generally it is faster than the cumulated speed of all things that connect to it. Not always, but always so fast that you generally don't care. It's like a super highway of thousands of lanes, but only a quarter mile long
So insane bandwidth, no latency.Every packet that goes into or out of the switch travels between the ports via the backplane. It's what connects the whole thing together.
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@scottalanmiller said in VLAN confusion:
For your own learning, try working backwards. Where in a switch do you perceive bottlenecks or performances issues? See if you can figure out what you are picturing, maybe there is a misconception that we can address.
Well at this point, I see the potential bottlenecks being at the points where our switches connect to each other. We currently have six layer 3 Dell PowerConnect switches that all connect to each other via Link Aggregation/portshield groups. At the "center", we have all our servers and computers in our main building that connect to a stack of switches (stacked with mini-SAS) and then on that stack, there are a couple of LAG groups consisting of 3 ports each that run off to four different closets. Actually, one of them is our basement, which ... you know, screw it. I'm uploading a diagram I just did in MS Paint so you can see our layout. I'm aware that there are issues with the design:
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@dave247 said in VLAN confusion:
Well at this point, I see the potential bottlenecks being at the points where our switches connect to each other.
Those are called the ports and are what I mentioned. But the issue there is outside of the switch, not inside it. This is exactly why you want to avoid VLANs, because VLANs make you use those bottlenecks more often.
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So in that diagram, the bottlenecks would remain even if you segmented by network addressing. As long as the data needs to get from the core to the edge over the same LAG group, the bottleneck remains identical, regardless of the number or segmentation of the switches out at the edge.
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@scottalanmiller said in VLAN confusion:
So in that diagram, the bottlenecks would remain even if you segmented by network addressing. As long as the data needs to get from the core to the edge over the same LAG group, the bottleneck remains identical, regardless of the number or segmentation of the switches out at the edge.
Yeah, I get that. At this point, I'm all for having our phones and computers on the same network (as our current system is)... I just need to convince my boss now. I've only recently persuaded him to not have us use actual separate switches (not sure if you remember that conversation).
I should also try to figure out another possible voice solution, otherwise we are likely going with Cisco through that company... slams head down on desk
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@dashrender said in VLAN confusion:
@jaredbusch said in VLAN confusion:
Then you change your few static devices (if you do not have only a few static systems, you have other issues).
What JB means by this is - he uses static assignments in DHCP for things like printers. This allows you to reboot a printer to get the new settings when things like this change.
Servers are about the only thing that should be set statically, the rest can rely on Static DHCP assignment.
Domain Controller would pretty much be the only server that needs to be manually set to static.
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@black3dynamite said in VLAN confusion:
@dashrender said in VLAN confusion:
@jaredbusch said in VLAN confusion:
Then you change your few static devices (if you do not have only a few static systems, you have other issues).
What JB means by this is - he uses static assignments in DHCP for things like printers. This allows you to reboot a printer to get the new settings when things like this change.
Servers are about the only thing that should be set statically, the rest can rely on Static DHCP assignment.
Domain Controller would pretty much be the only server that needs to be manually set to static.
Yeah but if DNS and/or DHCP went down, you will probably have trouble getting to your servers. Static IP's on all system critical servers seems like a better decision since they will function in almost any environment state.
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@dave247 said in VLAN confusion:
@black3dynamite said in VLAN confusion:
@dashrender said in VLAN confusion:
@jaredbusch said in VLAN confusion:
Then you change your few static devices (if you do not have only a few static systems, you have other issues).
What JB means by this is - he uses static assignments in DHCP for things like printers. This allows you to reboot a printer to get the new settings when things like this change.
Servers are about the only thing that should be set statically, the rest can rely on Static DHCP assignment.
Domain Controller would pretty much be the only server that needs to be manually set to static.
Yeah but if DNS and/or DHCP went down, you will probably have trouble getting to your servers. Static IP's on all system critical servers seems like a better decision since they will function in almost any environment state.
Not unless you have a stupidly short lease time. I use 8 hour leases on most LAN stuff. Yeah it tries to renew every 4, but it will not require a DHCP server until 8 hours.
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@scottalanmiller said in VLAN confusion:
@dave247 said in VLAN confusion:
@scottalanmiller said in VLAN confusion:
@dave247 said in VLAN confusion:
They've mentioned setting up a VLAN for the phone system and setting up a voice router for it.
Of course he has, your CIO decided on this path when he brought in a Cisco networking salesman to screw the company. That decision was made ahead of time. Cisco uses their phones as a leader to get companies to buy inappropriate networking equipment. This is a completely "by the book" unscrupulous sales tactic for VoIP sales people.
Well we are probably going to go with them and I might not have much of a say... so it's going to be difficult for me to try to pressure these people to install a system in a way different than how they usually do it. Is there any material I can reference to "prove" that VLAN's are not needed and that voice and data are fine on the same network? Actually, now that i think of it, our current voice and data are on the same network and we have no issues.
Also, regarding QoS, didn't you mention something about having the QoS set up on the VoIP RTP service rather than the voice VLAN?
Things to take to your CEO (I'd honestly share this thread with him and tell him that I'm local, have an SEC background, have worked with Ray Dalio, have been in the biggest banks and hedges in the world, and will happily stop by to discuss financial ethics and rogue actors issues with him to explain the problem being perceived) would include...
https://www.smbitjournal.com/2011/07/never-get-advice-from-a-reseller-or-vendor/
https://www.smbitjournal.com/2016/06/buyers-and-sellers-agents-in-it/
https://www.smbitjournal.com/2017/07/the-social-contract-of-sales/And...
Scott, I watched/listened to your video. That puts it very very well. Do you have that in text format at all (it looked like you were reading from something). If so, I could probably use that as an informational source to submit to my boss.
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@jaredbusch said in VLAN confusion:
@dave247 said in VLAN confusion:
@black3dynamite said in VLAN confusion:
@dashrender said in VLAN confusion:
@jaredbusch said in VLAN confusion:
Then you change your few static devices (if you do not have only a few static systems, you have other issues).
What JB means by this is - he uses static assignments in DHCP for things like printers. This allows you to reboot a printer to get the new settings when things like this change.
Servers are about the only thing that should be set statically, the rest can rely on Static DHCP assignment.
Domain Controller would pretty much be the only server that needs to be manually set to static.
Yeah but if DNS and/or DHCP went down, you will probably have trouble getting to your servers. Static IP's on all system critical servers seems like a better decision since they will function in almost any environment state.
Not unless you have a stupidly short lease time. I use 8 hour leases on most LAN stuff. Yeah it tries to renew every 4, but it will not require a DHCP server until 8 hours.
I set mine to three days.
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@coliver said in VLAN confusion:
@jaredbusch said in VLAN confusion:
@coliver said in VLAN confusion:
@dashrender said in VLAN confusion:
@coliver said in VLAN confusion:
@dave247 said in VLAN confusion:
in the meantime, are there any good voice solution alternatives that you guys could provide? Part of our requirement for our phones is that we may not want to have it cloud-hosted due to the fact that our internet connection goes down every so often during business hours. YES I get that this is another problem that should be resolved vs applying a bandaid, but we live out in the country and have limited ISP options (Spec---m and Centu---ink).
FreePBX will probably meet your needs as it generally meets the needs of most people. It's opensource and free, can be hosted in house, and integrates with any SIP based IP Phone. There are people, here in the community that support it.
And will likely cost 1/10 what Cisco will cost. Seriously, you should give @JaredBusch a call and ask him to quote you a full on replacement and compare it's cost to Cisco.
1/10? I'd be surprised if it cost 1/100th.
Well, I'm not that cheap of a date.
Haven't seen Cisco pricing lately?
Ever heard of a Cisco voice router costing $250,000?
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@black3dynamite said in VLAN confusion:
@coliver said in VLAN confusion:
@jaredbusch said in VLAN confusion:
@coliver said in VLAN confusion:
@dashrender said in VLAN confusion:
@coliver said in VLAN confusion:
@dave247 said in VLAN confusion:
in the meantime, are there any good voice solution alternatives that you guys could provide? Part of our requirement for our phones is that we may not want to have it cloud-hosted due to the fact that our internet connection goes down every so often during business hours. YES I get that this is another problem that should be resolved vs applying a bandaid, but we live out in the country and have limited ISP options (Spec---m and Centu---ink).
FreePBX will probably meet your needs as it generally meets the needs of most people. It's opensource and free, can be hosted in house, and integrates with any SIP based IP Phone. There are people, here in the community that support it.
And will likely cost 1/10 what Cisco will cost. Seriously, you should give @JaredBusch a call and ask him to quote you a full on replacement and compare it's cost to Cisco.
1/10? I'd be surprised if it cost 1/100th.
Well, I'm not that cheap of a date.
Haven't seen Cisco pricing lately?
Ever heard of a Cisco voice router costing $250,000?
Is that a real price for a router??!
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@dave247 said in VLAN confusion:
@jaredbusch said in VLAN confusion:
@dave247 said in VLAN confusion:
@black3dynamite said in VLAN confusion:
@dashrender said in VLAN confusion:
@jaredbusch said in VLAN confusion:
Then you change your few static devices (if you do not have only a few static systems, you have other issues).
What JB means by this is - he uses static assignments in DHCP for things like printers. This allows you to reboot a printer to get the new settings when things like this change.
Servers are about the only thing that should be set statically, the rest can rely on Static DHCP assignment.
Domain Controller would pretty much be the only server that needs to be manually set to static.
Yeah but if DNS and/or DHCP went down, you will probably have trouble getting to your servers. Static IP's on all system critical servers seems like a better decision since they will function in almost any environment state.
Not unless you have a stupidly short lease time. I use 8 hour leases on most LAN stuff. Yeah it tries to renew every 4, but it will not require a DHCP server until 8 hours.
I set mine to three days.
Then you won't have a problem if the DHCP server is missing.
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@black3dynamite said in VLAN confusion:
@coliver said in VLAN confusion:
@jaredbusch said in VLAN confusion:
@coliver said in VLAN confusion:
@dashrender said in VLAN confusion:
@coliver said in VLAN confusion:
@dave247 said in VLAN confusion:
in the meantime, are there any good voice solution alternatives that you guys could provide? Part of our requirement for our phones is that we may not want to have it cloud-hosted due to the fact that our internet connection goes down every so often during business hours. YES I get that this is another problem that should be resolved vs applying a bandaid, but we live out in the country and have limited ISP options (Spec---m and Centu---ink).
FreePBX will probably meet your needs as it generally meets the needs of most people. It's opensource and free, can be hosted in house, and integrates with any SIP based IP Phone. There are people, here in the community that support it.
And will likely cost 1/10 what Cisco will cost. Seriously, you should give @JaredBusch a call and ask him to quote you a full on replacement and compare it's cost to Cisco.
1/10? I'd be surprised if it cost 1/100th.
Well, I'm not that cheap of a date.
Haven't seen Cisco pricing lately?
Ever heard of a Cisco voice router costing $250,000?
Have I? No my comment was slightly tongue in check. But between phones, hardware, and software licensing I'd guess the savings would be much better then what was recommended.
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@scottalanmiller said in VLAN confusion:
@dave247 said in VLAN confusion:
@dashrender said in VLAN confusion:
@jaredbusch said in VLAN confusion:
Then you change your few static devices (if you do not have only a few static systems, you have other issues).
What JB means by this is - he uses static assignments in DHCP for things like printers. This allows you to reboot a printer to get the new settings when things like this change.
Servers are about the only thing that should be set statically, the rest can rely on Static DHCP assignment.
oh man.. the printers.. I forgot about all the statically assigned printers we have. My company has about 30 statically assigned printers. That will be a huge pain in the butt to change..
Move them to DHCP while you do it. two bird, one stone.
But remember, if the things in the new range don't need to print, no need to change them.
Might want take a look at his print server if he is using it too before making those changes too.
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@jaredbusch said in VLAN confusion:
@dave247 said in VLAN confusion:
@jaredbusch said in VLAN confusion:
@dave247 said in VLAN confusion:
@black3dynamite said in VLAN confusion:
@dashrender said in VLAN confusion:
@jaredbusch said in VLAN confusion:
Then you change your few static devices (if you do not have only a few static systems, you have other issues).
What JB means by this is - he uses static assignments in DHCP for things like printers. This allows you to reboot a printer to get the new settings when things like this change.
Servers are about the only thing that should be set statically, the rest can rely on Static DHCP assignment.
Domain Controller would pretty much be the only server that needs to be manually set to static.
Yeah but if DNS and/or DHCP went down, you will probably have trouble getting to your servers. Static IP's on all system critical servers seems like a better decision since they will function in almost any environment state.
Not unless you have a stupidly short lease time. I use 8 hour leases on most LAN stuff. Yeah it tries to renew every 4, but it will not require a DHCP server until 8 hours.
I set mine to three days.
Then you won't have a problem if the DHCP server is missing.
Are all the address leases synchronized to the same time or do leases expire x amount of days after each individual host received it's address? If that's the case, there may be staggered renewal times and I wouldn't know what system is going to expire when.. (I just realized I didn't know this)
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@dave247 said in VLAN confusion:
@jaredbusch said in VLAN confusion:
@dave247 said in VLAN confusion:
@jaredbusch said in VLAN confusion:
@dave247 said in VLAN confusion:
@black3dynamite said in VLAN confusion:
@dashrender said in VLAN confusion:
@jaredbusch said in VLAN confusion:
Then you change your few static devices (if you do not have only a few static systems, you have other issues).
What JB means by this is - he uses static assignments in DHCP for things like printers. This allows you to reboot a printer to get the new settings when things like this change.
Servers are about the only thing that should be set statically, the rest can rely on Static DHCP assignment.
Domain Controller would pretty much be the only server that needs to be manually set to static.
Yeah but if DNS and/or DHCP went down, you will probably have trouble getting to your servers. Static IP's on all system critical servers seems like a better decision since they will function in almost any environment state.
Not unless you have a stupidly short lease time. I use 8 hour leases on most LAN stuff. Yeah it tries to renew every 4, but it will not require a DHCP server until 8 hours.
I set mine to three days.
Then you won't have a problem if the DHCP server is missing.
Are all the address leases synchronized to the same time or is do leases expire x amount of days after each individual host received it's address? If that's the case, there may be staggered renewals and I wouldn't know what system is going to expire when.. (I just realized I didn't know this)
You are correct that they happen randomly based on the machine that requested, but with a 3 day lease, the odds are low to be greatly impacted for any minor outage.
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@jaredbusch said in VLAN confusion:
@dave247 said in VLAN confusion:
@jaredbusch said in VLAN confusion:
@dave247 said in VLAN confusion:
@jaredbusch said in VLAN confusion:
@dave247 said in VLAN confusion:
@black3dynamite said in VLAN confusion:
@dashrender said in VLAN confusion:
@jaredbusch said in VLAN confusion:
Then you change your few static devices (if you do not have only a few static systems, you have other issues).
What JB means by this is - he uses static assignments in DHCP for things like printers. This allows you to reboot a printer to get the new settings when things like this change.
Servers are about the only thing that should be set statically, the rest can rely on Static DHCP assignment.
Domain Controller would pretty much be the only server that needs to be manually set to static.
Yeah but if DNS and/or DHCP went down, you will probably have trouble getting to your servers. Static IP's on all system critical servers seems like a better decision since they will function in almost any environment state.
Not unless you have a stupidly short lease time. I use 8 hour leases on most LAN stuff. Yeah it tries to renew every 4, but it will not require a DHCP server until 8 hours.
I set mine to three days.
Then you won't have a problem if the DHCP server is missing.
Are all the address leases synchronized to the same time or is do leases expire x amount of days after each individual host received it's address? If that's the case, there may be staggered renewals and I wouldn't know what system is going to expire when.. (I just realized I didn't know this)
You are correct that they happen randomly based on the machine that requested, but with a 3 day lease, the odds are low to be greatly impacted for any minor outage.
So if a couple of servers have leases that expire 10 minutes after my DHCP server goes down (DC dies or something) then that's going to be more systems down. I wouldn't want to risk it..
