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three new CSS326 on existing network

Posted: Wed Jul 10, 2019 10:42 pm
by vincenthimpe
Given : existing network with a router at 192.168.1.254

i will connect switch 1 to 2 using a sfp cable and switch 2 to 3 with a sfp cable.
port 1 of switch 1 will be plugged into network and all three switches will power up in random order. For the sake of creating problems: switch 3 will power up first , well before two and 1 are ready.

What will happen ?
i understand that , if no router is seen the switches autoconfigure their config console to 192.168.88.1. Since switch 2 and 1 are not ready yet that means that switch 3 will not get a dhcp form the router.

even then : if all three power up there will be a network conflict as there will be more than one device at 192.168.88.1

So how do i avoid these problems. ?

i am thinking about upgrading my network but i do not want to find out that there is a need for endless muckery with hooking up computers , with hardcoded network address , to swtiches to configue them , then plugging them into the router and other kjumping through hoops.
Same question after a power failure. The order in which these things return from power loss is unknown. What will happen ?

thanks.

Re: three new CSS326 on existing network

Posted: Thu Jul 11, 2019 12:26 pm
by sid5632
i understand that , if no router is seen the switches autoconfigure their config console to 192.168.88.1
You understand wrongly.
even then : if all three power up there will be a network conflict as there will be more than one device at 192.168.88.1
There won't.
So how do i avoid these problems. ?
Design it properly. Don't use chains of switches. Don't use DHCP. Configure static addresses.

Re: three new CSS326 on existing network

Posted: Thu Jul 11, 2019 10:52 pm
by mkx
Don't use chains of switches. Don't use DHCP. Configure static addresses.

I don't see any problem with chain of switches, specially not in context presented by OP.

I do agree with the second part: don't use DHCP to configure management interfaces of network infrastructure devices.

Re: three new CSS326 on existing network

Posted: Fri Jul 12, 2019 12:41 am
by sid5632
I don't see any problem with chain of switches, specially not in context presented by OP.
Apart from the multiple single points of failure?

Re: three new CSS326 on existing network

Posted: Fri Jul 12, 2019 8:04 am
by vincenthimpe
Here is my setup : one switch in the living room , one in the office, and one where my router and nas boxes sit. The middle one has one 10g link going to office and the other 10g link going to living room.
- living room has all the media stuff , tv, blu ray, ipcams , home automation , gameboxes etc.
- office has computers and printers
- the middle one sits in the network cabinet where the router and multiple nasses sit.

Living room access only internet and nas boxes.
office accesses only nas boxes and internet.

i have used this topology for 10 years without a single problem ( Netgear switches and router). Now i want a fatter pipe from the network cabinet to office and living room. Mikrotik CSS326 has two SFP+ ports capable of 10G. perfect. i already have cat6 in the wall and the distances that need bridging is barely 20 feet.

So, instead of making sarcastic comments that provide no information : Here is the question :

On power up the management console starts at 192.168.88.1 (see documentation for the css326). As each of the three switches powers up with that default address, There is now an ip address conflict. How do i solve that ? power up the middle one first , log in to the console , change the ip , then power up the next , configure that one and finally the third one ?

My hardware arrives tomorrow and i want to be prepared. I've never dealt with switches that have management. so far i used simple unmanaged switches but i want to go to 10G links. When my office computers are moving bulk data to the NAS the 1g link is overloaded so i want a bigger pipe there.

Re: three new CSS326 on existing network

Posted: Fri Jul 12, 2019 1:55 pm
by mkx
On power up the management console starts at 192.168.88.1 (see documentation for the css326). As each of the three switches powers up with that default address, ...

That's merely default. When your switches arrive and you start configuring them, you'll plug one at the time. It'll get some address from your existing (and working) DHCP server. You'll connect to that dynamic IP address and set a static one instead. So next time it boots, it'll assume the static address you entered and won't bother with DHCP stuff again.

Mind that (almost?) every device has two possibilities about IP address configuration: obtaining dynamic address via DHCP or setting static address. While using DHCP is preferred way for usual devices (including some servers but not all) because IP address space management is done centrally (on DHCP server ... where one can configure static leases, so devices get pseudo-static addresses, if non-changing IP address is preferred) ... it is not feasible for certain device types. LAN infrastructure devices fall into this class ... and include routers, switches and DHCP server itself (perhaps some more).

Re: three new CSS326 on existing network

Posted: Fri Jul 12, 2019 4:38 pm
by vincenthimpe
Thanks a lot. That is what i wanted to know. So one at a time is the way to go.

Another user on the forum discovered that SWos 2.6 did not have the capability to lease a DHCP address.
This was fixed in 2.7. He had to go through growing pains to update the firmware. (downloading th efile on a computer, changing the computers ip configuration to get it on the 192.168.88.xx , flashing the firmware , then rebooting all and undoing the computer config so it would go back to dhcp and lease from 192.168.1.xx