[120466] in North American Network Operators' Group
RE: how it routes and network question
daemon@ATHENA.MIT.EDU (Bruce Forster)
Tue Dec 22 07:49:58 2009
From: "Bruce Forster" <bruce@tubes.net.au>
To: "'Deric Kwok'" <deric.kwok2000@gmail.com>
In-Reply-To: <40d8a95a0912220431p7232025bx338affded04c8bd0@mail.gmail.com>
Date: Tue, 22 Dec 2009 22:48:04 +1000
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
<SNIP>
Yes. I think the netmask should be 255.255.255.255
1/ but why they are using this netmask setting? save ip address?
then does the router handle many routes in this setting?
</SNIP>
I have no idea the only way you can have a /32 is with a ppp that =
doesn=92t
use arps to talk to each end of the tunnel.
I would assume they have /24's and are giving out /32 via dhcp to =
customers
and the customers should see 255.255.255.0 with a gateway of eg, .1 =
etc..
<SNIP>
2/ What is this advantage for the hosting company?
</SNIP>
If the company is setup the way i think it is the only reason for this =
is:
1, they have no clue what they are doing
2, they offer a very cheap hosting service and have no managed switches, =
and
don=92t understand how to subnet and use vlan's.
<SNIP>
3/ If I need more ip in the same server, how it works?
</SNIP>
I would of thought if you have 2 x servers you wanted to co-locate the
hosting company would offer you a /29 with 1 gateway 1 broadcast and 4
useable on a vlan, so local traffic only sits on the vlan and the =
servers
can talk to each other via the local vlan.
I guess if the machines have more then 1 nic you can connect the 2 =
machines
via a local 'backnet' network it can be useful if you have a cross-over
cable between the 2 x machines and its a 1GB port. This also saves using =
the
switches, in some cases hosting companies may count all traffic that =
goes
over the interface (if they don=92t use net flow) and you could end up =
paying
for traffic which you really shouldn=92t have to pay for.=20
If you are using the additional ports for high amounts of data eg, =
backup's
images etc, you can really tweak tcp settings so you can send JUMBO =
frames
and squeeze some speed out of it.
<SNIP>
4/ Why you said the hosting company is cheap to use this configuration?
</SNIP>
Yes its alot cheaper to have say a common-gateway that all traffic will
route over and then connect a bunch of switches to this common router =
and
manage it via dhcp, its very messy and also very noisy i can only =
imagine
after you connect a few servers that over time you will see arp storms =
and
all traffic on the network will cease to flow.
As mentioned in my other posts how it should be done, clearly you need =
to
buy layer 3 switches and layer 2 switches and a nice core router to deal
with your bgp, you also need to make sure your using devices that can =
handle
high packets per second.
As i am writing this i feel as if im doing someone homework for them... =
;P
Thank you again.
>
> <SNIP>
> 2/ lf =A0the network card in server has problem and need change =
another
> one, will my ip address change to another ip address also?
> </SNIP>
> Yeah well thats how dhcp works, via ma caddy, i guess you can always =
spoof
> your old mac address.
>
> <SNIP>
> 3/ why hosting company is using /32 and dhcp? what is advantage? ls it
> easy for administration?
> </SNIP>
> Im guessing because the users are to stupid to understand what a =
subnet
> mask/gateway is its just easier to get the mac address and assign it =
to a
> user then let the user assign a ip.
>
>
> Normally in a co-location setup its not like this, inless its very =
cheap
> hosting.
>
> My co-location has the following setup, and this is how MOST networks
should
> be run.
>
> Core router using BGP to transit providers, and other local peers.
> Switched network useing ospf to handle the routes and also VLAN's for =
the
> customers subnets.
>
> So customer should get a vlan assigned to them (which they have no =
need to
> know what the number is, they are handed a access mode port.
> Customers also issued a /30 (at least) in most cases a customer will =
get a
> /29 or /28 depending on what they need.
> In this case of a /30 its a total of 3 address's
> 1, GATEWAY (put on the ISP/HOST switch
> 2, IP ADDRESS FOR SERVER TO USE
> 3, BROADCAST ADDRESS.
>
> Heres an eg of a /30:
>
> Address: =A0 192.168.1.1 =A0 =A0 =A0 =A0 =
=A011000000.10101000.00000001.000000 01
> Netmask: =A0 255.255.255.252 =3D 30 11111111.11111111.11111111.111111 =
00
> Wildcard: =A00.0.0.3 =A0 =A0 =A0 =A0 =A0 =A0 =
=A000000000.00000000.00000000.000000 11
> =3D>
> Network: =A0 192.168.1.0/30 =A0 =A0 =A0 =
11000000.10101000.00000001.000000 00
> HostMin: =A0 192.168.1.1 =A0 =A0 =A0 =A0 =
=A011000000.10101000.00000001.000000 01
> HostMax: =A0 192.168.1.2 =A0 =A0 =A0 =A0 =
=A011000000.10101000.00000001.000000 10
> Broadcast: 192.168.1.3 =A0 =A0 =A0 =A0 =
=A011000000.10101000.00000001.000000 11
> Hosts/Net: 2 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Class C, Private =
Internet
>
>
> Heres an eg of a /29:
>
> the % ipcalc 192.168.1.1/29
> Address: =A0 192.168.1.1 =A0 =A0 =A0 =A0 =
=A011000000.10101000.00000001.00000 001
> Netmask: =A0 255.255.255.248 =3D 29 11111111.11111111.11111111.11111 =
000
> Wildcard: =A00.0.0.7 =A0 =A0 =A0 =A0 =A0 =A0 =
=A000000000.00000000.00000000.00000 111
> =3D>
> Network: =A0 192.168.1.0/29 =A0 =A0 =A0 =
11000000.10101000.00000001.00000 000
> HostMin: =A0 192.168.1.1 =A0 =A0 =A0 =A0 =
=A011000000.10101000.00000001.00000 001
> HostMax: =A0 192.168.1.6 =A0 =A0 =A0 =A0 =
=A011000000.10101000.00000001.00000 110
> Broadcast: 192.168.1.7 =A0 =A0 =A0 =A0 =
=A011000000.10101000.00000001.00000 111
> Hosts/Net: 6 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Class C, Private =
Internet
>
> Hope this makes sence.
>
> Regards,
>
> Bruce
>
>
>
