Advice Please - Extending a Network
I have an existing local network connected using 'old' ethernet nics and coax cabling. It is connected via a Linux 8.2 machine to the internet on a Broadband Cable Modem. The Linux machine is a gateway and runs DHCP, DNS, Squid, SuSEFirewall2, Samba to provide services to the network. I want to progressively migrate the local connections to 100 Mb/s Twisted Pair, so during the transition I shall have a third nic in the machine with some hosts on the coax and some on the RJ45/100 Mb/s How do I configure the services to support the additional local network, with minimum disruption to the existing (unmigrated hosts). The Linux machine has a fixed IP address in the local net (192.168.0.101) and allocates IP addresses in the range 192.168.0.102-199. I want all the hosts to continue to 'see' one another during the transition. Can I uses similar addresses on the new subnet (e.g. set the nic as 192.168.0.201 and assign addresses 192.168.0.202-299) or do I need to use a new subnet (e.g 192.168.1.xxx) Many thanks for specific advice or some pointers to where to find the answers. Philip
On Friday 09 January 2004 23:07, Philip B Cook wrote:
I have an existing local network connected using 'old' ethernet nics and coax cabling. It is connected via a Linux 8.2 machine to the internet on a Broadband Cable Modem.
The Linux machine is a gateway and runs DHCP, DNS, Squid, SuSEFirewall2, Samba to provide services to the network.
I want to progressively migrate the local connections to 100 Mb/s Twisted Pair, so during the transition I shall have a third nic in the machine with some hosts on the coax and some on the RJ45/100 Mb/s
How do I configure the services to support the additional local network, with minimum disruption to the existing (unmigrated hosts).
The Linux machine has a fixed IP address in the local net (192.168.0.101) and allocates IP addresses in the range 192.168.0.102-199.
I want all the hosts to continue to 'see' one another during the transition. Can I uses similar addresses on the new subnet (e.g. set the nic as 192.168.0.201 and assign addresses 192.168.0.202-299) or do I need to use a new subnet (e.g 192.168.1.xxx)
Many thanks for specific advice or some pointers to where to find the answers.
Philip
Don't add another nic, It complicates matters beyond need. Replace your existing server nic with a 10/100 nic, any one will do, intel works nice, as do most of the $10 nics. Go down to the computer store and find a SMALL (5port) 10/100 switch (or hub). If lucky, you will find one with a cat5 port as well as a coax port. Connect coax to it, and plug your server into one of the cat 5 ports, or any combination of that which works. Remember, all you want this cheap hub/switch for is its coax port. So if you can't find one, buy one without a coax port and offer it in trade to anyone who has an older hub which almost always had coax ports. Since you will be buying a big switch to handle the whole house anyway, make sure its 10/100 autosensing, and you can plug any old 10meg hub into it to carry the load till you cut over. Don't add another nic, its just more routeing problems than you need. -- _____________________________________ John Andersen
Hi there, Am Sam, den 10.01.2004 schrieb John Andersen um 10:56:
Don't add another nic, It complicates matters beyond need.
He's right. Replace NICs in every PC step by step, beginning with the server.
Replace your existing server nic with a 10/100 nic, any one will do, intel works nice, as do most of the $10 nics.
An additional hint: buy a nic that takes away stress from the CPU. Cheaper NICs leave much work to the CPU, like those Realtek chipsets. This is not a problem with fast CPUs but you'll notice the difference on weaker machines, like the battered Pentiums that route my network. A 3COM or Intel is usually a good choice.
Go down to the computer store and find a SMALL (5port) 10/100 switch (or hub).
Don't buy a hub. Buy a switch. I'm not sure this is totally right, but as far as I know a hub only takes the lowest speed connected while a switch can mix 100MBit and 10MBit. Is this right or do I confuse something here? I don't know for sure but I heard that switches have less problems with packet collisions because they route by hardware address? Does this make sense? I have two low cost 8 Port Switches here at home and they work perfectly fine.
If lucky, you will find one with a cat5 port as well as a coax port. Connect coax to it, and plug your server into one of the cat 5 ports, or any combination of that which works.
Actually, you don't need a switch/hub with a coax port. Since you're moving away from coax cable soon, you can as well connect those old 10MBit NICs with twisted par cables immediately. I assume those old NICs you are going to replace have a connection for coax AND twisted pair? Normally a 10MBit card has those two connectors. If yes, don't invest in something you are not going to need in the future. Buy a regular switch, buy cables to replace every coax cable now and replace NICs step by step.
Remember, all you want this cheap hub/switch for is its coax port. So if you can't find one, buy one without a coax port and offer it in trade to anyone who has an older hub which almost always had coax ports.
See alternative above.
Since you will be buying a big switch to handle the whole house anyway, make sure its 10/100 autosensing, and you can plug any old 10meg hub into it to carry the load till you cut over.
I totally agree. But you don't need the coax connection if you replace the cabling immediately. You don't have to change a thing at the old PCs if you use twisted pair instead of coax, so there really isn't any need to stick with the coax.
Don't add another nic, its just more routeing problems than you need.
Yes, this is true. It would be another story if you were using a token ring network though ;-) cheers, Tobias W.
Sorry Tobias,
I was obviously in the middle of constructing my email at the same time as
you!
You are right, only a switch, some "bridges" or linux box configured as a
bridge can route ethernet traffic between network segments that are using
different types of ethernet packets (802.3, 802.3 SNAP, ethernet II a.k.a.
"DIX", fast ethernet, gigabit ethernet, etc.)
This is because hubs are like wires/coax, they just flash all packets
everywhere. Switches act a bit like routers, after discovering which NIC is
connected to which port they route packets down only that wire (in a sense).
See http://www.howstuffworks.com/lan-switch.htm for an excellent, simple
explanation.
I agree that if cost is not an issue and the cost doesn't need to be spread
out over months/years then it's best to start migrating machines ASAP, that
way you can shake down problems as fast as possible.
The only thing to watch out for is that you shouldn't replace coax in a
"noisy" environment (electronically speaking), example would be in a machine
shop where electromagnetic interference might cause twisted pair networks to
malfunction, resulting in excessive packet loss.
Carl
----- Original Message -----
From: "Tobias Weisserth"
Hi there,
Am Sam, den 10.01.2004 schrieb John Andersen um 10:56:
Don't add another nic, It complicates matters beyond need.
He's right. Replace NICs in every PC step by step, beginning with the server.
Replace your existing server nic with a 10/100 nic, any one will do, intel works nice, as do most of the $10 nics.
An additional hint: buy a nic that takes away stress from the CPU. Cheaper NICs leave much work to the CPU, like those Realtek chipsets. This is not a problem with fast CPUs but you'll notice the difference on weaker machines, like the battered Pentiums that route my network. A 3COM or Intel is usually a good choice.
Go down to the computer store and find a SMALL (5port) 10/100 switch (or hub).
Don't buy a hub. Buy a switch. I'm not sure this is totally right, but as far as I know a hub only takes the lowest speed connected while a switch can mix 100MBit and 10MBit. Is this right or do I confuse something here? I don't know for sure but I heard that switches have less problems with packet collisions because they route by hardware address? Does this make sense?
I have two low cost 8 Port Switches here at home and they work perfectly fine.
If lucky, you will find one with a cat5 port as well as a coax port. Connect coax to it, and plug your server into one of the cat 5 ports, or any combination of that which works.
Actually, you don't need a switch/hub with a coax port. Since you're moving away from coax cable soon, you can as well connect those old 10MBit NICs with twisted par cables immediately. I assume those old NICs you are going to replace have a connection for coax AND twisted pair? Normally a 10MBit card has those two connectors. If yes, don't invest in something you are not going to need in the future. Buy a regular switch, buy cables to replace every coax cable now and replace NICs step by step.
Remember, all you want this cheap hub/switch for is its coax port. So if you can't find one, buy one without a coax port and offer it in trade to anyone who has an older hub which almost always had coax ports.
See alternative above.
Since you will be buying a big switch to handle the whole house anyway, make sure its 10/100 autosensing, and you can plug any old 10meg hub into it to carry the load till you cut over.
I totally agree. But you don't need the coax connection if you replace the cabling immediately. You don't have to change a thing at the old PCs if you use twisted pair instead of coax, so there really isn't any need to stick with the coax.
Don't add another nic, its just more routeing problems than you need.
Yes, this is true. It would be another story if you were using a token ring network though ;-)
cheers, Tobias W.
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On Saturday 10 January 2004 15.56, Tobias Weisserth wrote:
Hi there,
...
An additional hint: buy a nic that takes away stress from the CPU. Cheaper NICs leave much work to the CPU, like those Realtek chipsets. This is not a problem with fast CPUs but you'll notice the difference on weaker machines, like the battered Pentiums that route my network. A 3COM or Intel is usually a good choice. True - modern NICs have there own HW to offload the CPU.
Go down to the computer store and find a SMALL (5port) 10/100 switch (or hub).
Don't buy a hub. Buy a switch.
Again, true - a true hub only supports 10Mbps at half duplex. A good switch provides support for 100Mbps as well, including full duplex ie sending and receiving data at the same time. With a modern NIC you can take advantage of full duplex at 10MBps as well. Another advantage is microsegmentation of the network. Every switch port is in its own ethernet collision domain. This mean you will have less collisions and a cleaner traffic pattern in your network. A hub is just a dumb box with all ports in the same collison domain. You need Cat5 or better cabling to take advantage of full duplex communication. //RegardsTony
On Saturday 10 January 2004 05:56, Tobias Weisserth wrote:
An additional hint: buy a nic that takes away stress from the CPU. Cheaper NICs leave much work to the CPU, like those Realtek chipsets. This is not a problem with fast CPUs but you'll notice the difference on weaker machines, like the battered Pentiums that route my network. A 3COM or Intel is usually a good choice.
This is often mentioned, but never documented. As far as I know, no one anywhere has ever posted any quantative results of side by side tests. I stand ready to be corrected, but this is, IMHO, hogwash. The cpuload is simply not measurable in anything above a 486. -- _____________________________________ John Andersen
Hi John, Am Son, den 11.01.2004 schrieb John Andersen um 01:43:
On Saturday 10 January 2004 05:56, Tobias Weisserth wrote:
An additional hint: buy a nic that takes away stress from the CPU. Cheaper NICs leave much work to the CPU, like those Realtek chipsets. This is not a problem with fast CPUs but you'll notice the difference on weaker machines, like the battered Pentiums that route my network. A 3COM or Intel is usually a good choice.
This is often mentioned, but never documented.
As far as I know, no one anywhere has ever posted any quantative results of side by side tests. I stand ready to be corrected, but this is, IMHO, hogwash.
The cpuload is simply not measurable in anything above a 486.
I noticed a very high CPU load while copying using the Samba protocol. The Samba subprocess took almost 40% of CPU time (200MHz Pentium with 128MB). I had been using RealTek NICs. I replaced the RealTeks with cheap 3COM cards I got from Ebay and what do you know? CPU load went down considerably (about 15% taken by that Samba subprocess) and I have a slightly faster connection too. This is not an objective measurement but you may consider this as live experience. cheers, Tobias
On Saturday 10 January 2004 05:56, Tobias Weisserth wrote:
Actually, you don't need a switch/hub with a coax port. Since you're moving away from coax cable soon, you can as well connect those old 10MBit NICs with twisted par cables immediately.
No he can't. Didn'ty you read his post? He needs them on line while he systematically replaces/adds wireing. That's the whole crux of his post. I'm supprised you missed his major point. -- _____________________________________ John Andersen
Hello there, sorry my answer didn't come faster but I didn't get most of the list emails until now. Am Son, den 11.01.2004 schrieb John Andersen um 01:45:
No he can't. Didn'ty you read his post?
Yes he can and yes, I read his post.
He needs them on line while he systematically replaces/adds wireing. That's the whole crux of his post. I'm supprised you missed his major point.
No. Please read what I have written. A 10MBit NIC usually has TWO connectors. ONE for coax AND one for twisted pair. He can plug out the coax and plug in the twisted pair in the other connector and everything will run as usual. That's exactly why you should have read MY post before righting this. cheers, Tobias
On Sunday 11 January 2004 05:57, Tobias Weisserth wrote:
A 10MBit NIC usually has TWO connectors. ONE for coax AND one for twisted pair. He can plug out the coax and plug in the twisted pair in the other connector and everything will run as usual.
No, these are an either - or ports. You can not use both at the same time. If you had ever bothered to try this yourself you would know this. -- _____________________________________ John Andersen
Hi John, You don't want to understand me, do you? :-) Am Son, den 11.01.2004 schrieb John Andersen um 22:08:
On Sunday 11 January 2004 05:57, Tobias Weisserth wrote:
A 10MBit NIC usually has TWO connectors. ONE for coax AND one for twisted pair. He can plug out the coax and plug in the twisted pair in the other connector and everything will run as usual.
No, these are an either - or ports.
Read what I have written. If it helps read it aloud: He can plug out the coax. Can you follow me? Then he can plug in the twisted pair into the other connector. How many cable connections does he have in one card after he plugs out the coax and plugs in the twisted pair? This shouldn't be too hard to figure. It's one if that helps you ;-)
You can not use both at the same time.
Which I didn't say because he can replace ALL the coax cables WITHOUT having to change the 10MBit NICs immediately or any configuration settings at those PCs. If he plans to replace the coax cabling anyway there is really no point in sticking to it and add twisted pair additionally step by step. This only complicates things and makes it more expensive. A 10MBit NIC doesn't bother whether a coax cable or a twisted pair is connected. So get rid of the coax now and use twisted pair and then change the 10MBit cards step by step with 100MBit cards. It's as easy as this. Trust me, I've done it.
If you had ever bothered to try this yourself you would know this.
I do this all the time. It isn't that hard to replace one coax cable in a card and simply plug in a twisted pair cable into the other connector. BTW: no offence meant but you really should consider reading AND apprehending what I have written before posting. cheers, Tobias
John, Tobias, thank you each for all your help. I should prefer that you two do not come to 'metaphoric' blows over each helping me with advice. To amplify my original description of the situation, the pace of migration to the new network is determined by making the wiring changes (requiring lots of building work in my hose), so John's proposal makes the most sense. I am currently bidding on a 8port hub with a coax connection on Ebay in order to commence the work. None-the-less, I have learnt plenty from the ideas you have both presented. Thanks.. Philip
On Friday 09 January 2004 23:07, Philip B Cook wrote:
I have an existing local network connected using 'old' ethernet nics and coax cabling. It is connected via a Linux 8.2 machine to the internet on a Broadband Cable Modem.
The Linux machine is a gateway and runs DHCP, DNS, Squid, SuSEFirewall2, Samba to provide services to the network.
I want to progressively migrate the local connections to 100 Mb/s Twisted Pair, so during the transition I shall have a third nic in the machine with some hosts on the coax and some on the RJ45/100 Mb/s
How do I configure the services to support the additional local network, with minimum disruption to the existing (unmigrated hosts).
The Linux machine has a fixed IP address in the local net (192.168.0.101) and allocates IP addresses in the range 192.168.0.102-199.
I want all the hosts to continue to 'see' one another during the transition. Can I uses similar addresses on the new subnet (e.g. set
Philip,
For this new fast ethernet (100Mb) network you're putting in place you'll
almost certainly be buying new fast ethernet compatible switches anyway.
These are usually 10/100 compatible anyway. You can just connect your old
ethernet II/802.3/SNAP (10Mb) network into one of the ports on one of the
new switches. Switches are designed to do lots of clever stuff, including
ethernet level routing (often using "spanning tree" to allow loops in the
networks), full duplex and autosensing
(http://www.howstuffworks.com/lan-switch.htm). If you have to buy very dumb
switches or hubs (because of cost) that won't allow mixed speeds then this
won't work.
Remember, as John Andersen says you only need one autosensing switch to
connect together the ethernet II/802.3/SNAP LAN segment and the fast
ethernet segment, even if you can't afford the benefits of a switch for the
entire fast ethernet network. Think though that the switch is a critical
point of failure for the whole network and I've seen cheap switches that pop
out every few months leaving the users puzzled and in a panic until the
switch is power cycled!
If the hardware solutions described are not an option then you have two
options using Linux (i) seperate subnets or (ii) a bridge. The latter
consists of extra modules in the kernel which effectively turn your box into
a switch, thus saving the expense, and all LAN traffic goes across both
segments. Alternatively split the LAN into two subnets, have two IP
addresses, one for each NIC and have DHCP serve different IP addresses to
hosts on each segment. This is more traditional in some ways but can be
annoying for users, depending on what applications they use. For instance
if they are SMB clients that want to browse a "Network Neighbourhood" then
you'll need to implement a WINS server (and possibly a domain server) to
keep the two subnets talking to each other.
Carl Peto
Linux Server Support
Bookman Associates
----- Original Message -----
From: "John Andersen"
nic as 192.168.0.201 and assign addresses 192.168.0.202-299) or do I need to use a new subnet (e.g 192.168.1.xxx)
Many thanks for specific advice or some pointers to where to find the answers.
Philip
Don't add another nic, It complicates matters beyond need.
Replace your existing server nic with a 10/100 nic, any one will do, intel works nice, as do most of the $10 nics.
Go down to the computer store and find a SMALL (5port) 10/100 switch (or hub). If lucky, you will find one with a cat5 port as well as a coax port. Connect coax to it, and plug your server into one of the cat 5 ports, or any combination of that which works.
Remember, all you want this cheap hub/switch for is its coax port. So if you can't find one, buy one without a coax port and offer it in trade to anyone who has an older hub which almost always had coax ports.
Since you will be buying a big switch to handle the whole house anyway, make sure its 10/100 autosensing, and you can plug any old 10meg hub into it to carry the load till you cut over.
Don't add another nic, its just more routeing problems than you need.
-- _____________________________________ John Andersen
-- Check the headers for your unsubscription address For additional commands, e-mail: suse-security-help@suse.com Security-related bug reports go to security@suse.de, not here
Hi Philip, my experience is: if you offer more bandwith, they will use it! Nowadays most people need advice to upgrade their backbone from 100 to Giga... So my advice is: - buy a cheap GigaNIC (Copper, 32 Bit PCI) for your Server(s) - buy a good switch, 10/100 MBit, with GBIC-Slot or Copper-Gigabit uplink - buy a cheap (used) Hub with 10BaseT and 10Base2 - only use Cat6-cable (for Giga) for the new wiring, nearly no extra charge to Cat5 (only 100 MBit) - Think about technologies like vlan, Voice over IP, Power over Ethernet - don´t invest money in the wrong cabling - If you have to deal with elektrosmog, use fiber Advantages: - Your fileserver and "main" switch is prepared for the future - You can easily remove your coax "room for room", using the Hub at the end of the coax Greetings Thorsten ----- http://bynari.dbtec.de
participants (6)
-
Carl Peto -
John Andersen -
Philip B Cook -
Thorsten Hahn -
Tobias Weisserth -
Tony Stohne