Snakeoil Forums

Hi, pals,

I just came across this "function" in about a month ago.  Being a layman to IT, please excuse for my ignorance to VLAN, and correct me if I used the terms incorrectly.   

I wonder that, in CAS,:
1) Would setting up a VLAN reduce or increase the latency of the switch/router, so to the CAS system?
2) Would that reduced port broadcasting activity be "heard"?

Anyway, so happen my ASUS router was dead in last week and I brought a CISCO RV340W router, together my previous CISCO SG350 switch.  I'm try to build some VLAN in them, to isolate streaming TV box, streaming TV set, CAS, daily use PC, and so and so.

Here is my set up. 


I'll appreciate any suggestion or comment to my VLAN concern.  Thank you very much and Happy Listening. 

(06-Mar-2021, 11:40 AM)hkphantomgtr Wrote: [ -> ]1) Would setting up a VLAN reduce or increase the latency of the switch/router, so to the CAS system?

Using VLAN will add an extra 4 bytes in the ethernet packet. But in the all scheme of things, this is negligible if you ask me. Let's say you have configured 2 VLANs on a layer 2 switch (Say VLAN_A and VLAN_B) and a router. If you have a device on VLAN_A that needs to talk to another device on VLAN_B, it has to go to the router first then back (i.e. switch -> router -> switch).

If you have a lot of traffic going between VLANs, the bandwidth between your switch and router is a problem. E.g. if your link between switch and router is only 1 Gbps, this can be a problem if you're transferring large amounts of data between VLANs. In cases like this, then yes, it will be an issue.

But if you plan things well, then it will actually be better. Examples of better
1. Keep noisy traffic on it's own VLAN
2. Better security. You have all your IoT devices (very talkative) on it's own VLAN and seperate from your home network

So basically to get this done well, the switch and router both has to be able to forward at full speed, on all ports. Cisco hardware usually can do this, but check the specfications just to be sure.
 

(06-Mar-2021, 11:40 AM)hkphantomgtr Wrote: [ -> ]2) Would that reduced port broadcasting activity be "heard"?

It depends, but in general, yes. But you have to put some thought into the setup. e.g. disable DHCP, disable bonjour (and anything that does broadcasts), turn on IGMP snooping/querier. You can use tools like wireshark to look at the traffic that's currently running on the network.

See my example in this post.  The idea is to setup the network such that my CAS network card, only sees the NAS and my remote client and nothing else. The NAS can actually be talking to many other devices at the same time. But the traffic my CAS sees is very "clean". If your switch can do this, try to capture the data on the CAS network port and see what's transmitted to/from there. And then work backwards from there by removing unnecessary stuffs..

Turn off anything you don't need (STP, LLDP) but you have to be very extra careful and not make mistakes (e.g. STP is to prevent loops, LLDP helps you identify devices on your network. Both are good for troubleshooting).

(07-Mar-2021, 08:37 AM)agent_kith Wrote: [ -> ]

(06-Mar-2021, 11:40 AM)hkphantomgtr Wrote: [ -> ]1) Would setting up a VLAN reduce or increase the latency of the switch/router, so to the CAS system?

Using VLAN will add an extra 4 bytes in the ethernet packet. But in the all scheme of things, this is negligible if you ask me. Let's say you have configured 2 VLANs on a layer 2 switch (Say VLAN_A and VLAN_B) and a router. If you have a device on VLAN_A that needs to talk to another device on VLAN_B, it has to go to the router first then back (i.e. switch -> router -> switch).

If you have a lot of traffic going between VLANs, the bandwidth between your switch and router is a problem. E.g. if your link between switch and router is only 1 Gbps, this can be a problem if you're transferring large amounts of data between VLANs. In cases like this, then yes, it will be an issue.

But if you plan things well, then it will actually be better. Examples of better
1. Keep noisy traffic on it's own VLAN
2. Better security. You have all your IoT devices (very talkative) on it's own VLAN and seperate from your home network

So basically to get this done well, the switch and router both has to be able to forward at full speed, on all ports. Cisco hardware usually can do this, but check the specfications just to be sure.
 

(06-Mar-2021, 11:40 AM)hkphantomgtr Wrote: [ -> ]2) Would that reduced port broadcasting activity be "heard"?

It depends, but in general, yes. But you have to put some thought into the setup. e.g. disable DHCP, disable bonjour (and anything that does broadcasts), turn on IGMP snooping/querier. You can use tools like wireshark to look at the traffic that's currently running on the network.

See my example in this post.  The idea is to setup the network such that my CAS network card, only sees the NAS and my remote client and nothing else. The NAS can actually be talking to many other devices at the same time. But the traffic my CAS sees is very "clean". If your switch can do this, try to capture the data on the CAS network port and see what's transmitted to/from there. And then work backwards from there by removing unnecessary stuffs..

Turn off anything you don't need (STP, LLDP) but you have to be very extra careful and not make mistakes (e.g. STP is to prevent loops, LLDP helps you identify devices on your network. Both are good for troubleshooting).

Thanks a lot, Agent Kith!  Let me try try.