Can I connect a Modem/router to a wireless router (Linksys WRT54G)? I am
finding it hard to get hold of a stand alone ADSL modem with an ethernet
port.

Russ

"Mooncat" <no@btconnect.com> wrote in message news:<cjk6l2$n5b$1@hercules.btinternet.com>...
Yes, but this is really a bit of a kludge. Any machines connected to
the wired ports of the modem-router will be on a different subnet from
wirelessly-connected machines, and will be unable to file- &
print-share with them.

<http://www.broadbandbuyer.co.uk/Shop/ShopSearch.asp?CategoryID=34>

You really don't want to go this route.

Unless you're doing something clever like installing a different
version of Linux on the Linksys, get an all-in-one wireless ADSL
modem-router & flog the Linksys on fleeBay. There's a lot of
competition amongst manufactures of wireless ADSL routers at the
moment, and your Linksys will appeal to the "bargain hunters" on eBay.

Get one of these instead:
<http://www.broadbandbuyer.co.uk/Shop/ShopDetail.asp?ProductID=1094>
The PCMCIA card is free, or practically so, at the moment, and if you
don't want or need it you can always sell that on, too, to further
offset the costs. I wouldn't be surprised if this turned out cheaper
than your initial suggestions, and MUCH neater.

Stroller.

On 01 Oct 2004 in uk.telecom.broadband, acpul@pipex.net wrote:

The D-Link DSL 300T ethernet modem possibly fits the bill...

Does your Speedtouch internal have an ethernet port (needed by Mooncat) ?

In MsgID<385cfcc.0410011725.2cd9c2@posting.google.com > within
uk.telecom.broadband, 'Stroller' wrote:


I thought that was the whole purpose of a router?
To relay packets between (sub)networks?


--
Dave Johnson - requiem@freeuk.com

On 1 Oct 2004 18:25:09 -0700, stroller@bigfoot.com (Stroller) wrote:

Why?

Surely that will only be true if you set it up that way. There is no
reason why they have to be set up to use different subnets.



Why not?

If he was starting from scratch, I'd agree.

But from where he is, that saves him roughly 50%, although as you say,
that could be offset by selling his existing router.

But on the other hand, he already has things set up to work with his
existing router, and adding the modem would be trivial, for the sake
of one extra box, cable, and power lead.


--
Alex Heney, Global Villager
The brain you have reached is out of order at this time.

To reply by email, my address is alexATheneyDOTplusDOTcom

Dave J <requiem@freeuk.com> wrote in message news:<3n7tl0toananan4uni2nmerjoi0l9kgebo@4ax.com>. ..
Yes, but domestic routers typically do only one-way NAT t private
address space. Thus they allow packets from machines behind the router
to get out, and to receive replies, but drop all unsolicited requests
from outside the NAT.

However, as Mr Heney observes, the OP could most likely configure the
Linksys as a bridge, and avoid this problem. I don't know what I was
thinking, that I forgot this & apologise for the confusion.

Stroller.

In MsgID<385cfcc.0410030328.3209d1b@posting.google.co m> within
uk.telecom.broadband, 'Stroller' wrote:

Drop all unsolicited requests from outside the NATed IP block?

Sorry for silly questions, I'm still learning.

I'm still not quite sure on your meanings.

From where I'm sitting, it looks like the problem is one or more of
these things,

a) the modem router won't route (at all) between its wired ports[1].

b) you cannot set a subnet on the modem-router's wired port's IPs.
- So you couldn't connect a port to (say) a hub.

c) you cannot change the wireless router's subnet to match the
modem-router's.

d) The wireless router expects to NAT everything on the way out of a
special wired 'modem' port.

[1] If this is the case then IMHO it is not a router. Multi port modem
would be a better descriptor.

Thanks if you (or anyone else) explains. I am reasonably knowledgable
about 'real' routers/switches/networks but these toy things are liable
to flumox me into wasting some money if I don't suss them out first.

--
Dave Johnson - requiem@freeuk.com

In message <e110m0p1rasqpsukm4el323sc38krekoh3@4ax.com>, Dave J
<requiem@freeuk.com> writes
There's some crossed purposes going on here.

What is being talked here about is the one way I wouldn't connect the
two boxes together - connect the wired network devices to the ADSL
router and connect the WAN port of the wireless Ethernet router to the
ADSL router. That leaves the devices on the wireless double NATted and
on a different subnet to those wired devices.


Either connect one of the LAN ports of the wireless router to the ADSL
router and use it just as a wireless base station, or use the ADSL
router either in something like a half-bridge configuration (if you have
a single IP address) or no-NAT mode (if you have a routed IP block) and
connect everything to the wireless router.


It wasn't put very well IMHO - does it make sense now?


I've got a couple of bits of kit in the rack behind me one of which
doesn't really qualify for the toy description - but here's an example.


The ADSL router is a cheap ZyXEL Prestige 650H-E1 - there's no point
spending a lot of money on a decent ADSL router for my application.

I have a /29 with Zen - call it a.b.c.88 / 29 for argument.

Zen use the highest usable IP address for the router - so, in my case,
that's a.b.c.94 (a.b.c.95 is the broadcast address).


The Prestige is configured to have a LAN IP address of a.b.c.94, subnet
mask 255.255.255.248, and NAT is off, as is the firewall (no sensible
way of configuring it).

The Prestige is connected to the WAN 1 port of a ZyXEL ZyWALL 35, which
is a fairly decent multi-NAT router, firewall, bandwidth management,
dial backup (with a modem) and IPsec box, which supports multiple LAN
and DMZ subnets (two separate broadcast domains and sets of firewall
rules).


In fact, to make my life easier, the Prestige and ZyWALL are not
directly connected together - the connection goes through my managed
switch on a separate VLAN to the LAN, so that I can get at it from my
main workstation which supports tagged operation on multiple VLANs.

If you don't want the dual WAN features of the ZyWALL 35 and can get
away with fewer IPsec tunnels, the ZyWALL 5 is available for a little
over 200 pounds plus VAT - and IMHO is rather more powerful than even
the most expensive ADSL router (Cisco aside, most likely).

The Prestige 650H-E1 is only 35 pounds from broadbandbuyer.co.uk -
though it is capable of multi-NAT operation with a fairly decent
firewall just by itself; it also has a four port switch built in.


The ZyWALL is set up with an IP address of a.b.c.93, subnet mask
255.255.255.248, gateway address a.b.c.94 - and runs multi-NAT on the
other addresses in the block, also its firewall is on.



For single IP address accounts, this approach doesn't work. The easiest
thing to do is to buy a router with all the facilities you need built in
including the ADSL modem.

The alternative is to use a device that will pass through the IP
address. The PPP Half Bridge mode of Conexant based gear will do this
(though with the penalty of a very short DHCP lease) - Westell routers
have various techniques you can use (look up "Single Static IP" in the
Westell 6100 manual available from www.westell.com).

Ignore American references to PPPoE operation, where you can run the
ADSL kit as a bridge and terminate the PPPoE session on another piece of
equipment. PPPoA (as I think all UK ADSL ISPs use, with the exception of
some AOL connections) has to terminate on the DSL kit.


The manuals for all the ZyXEL kit can be got in PDF format from
ftp://ftp.zyxel.com




David
--
David Wood
david@wood2.org.uk

In MsgID<8QYwFEJE2BYBFAY2@wood2.org.uk> within uk.telecom.broadband,
'David Wood' wrote:

[..]

Yes, thank you for the further explanation, though I'm probably still
as confused.

I've taken my time replying as you set me looking things up, and
grepping some new stuff along with some of the things I'd already
heard about. Doesn't mean I've anything like got it right of course,
but you've helped a bit in provoking the reading.

The way I'd have *expected* it to work would have been for the
wireless router to route between the wireless devices, with the ADSL
router as its default route, and for the ADSL router to have NAT set
up only on its outgoing port, with that as /its/ default route, plus
routes for the wireless subnets. Hopefully it would then route between
the wireless devices and the wired ones with no need for NAT except
for unknown (external) destinations.

This leads me to think I still don't really understand the problem.

[..]

More than it did, my fault for dropping in to the middle of a
discussion I think.

[..]

So, it won't route at the same time as doing NAT only on the one
outgoing interface then?

This is horrible, I'm realising just how little I know..
BTW, that's in spite of getting constant middle 90s in the subtests
and EOS exams up to 3/4 of the way through a CCNA course (ie now)

Fair enough, by my standards that is *not* a toy..

[..]
Sounds a good recomendation to me, esp as it's happy with VPN.

Ah, multi-nat means nat to/from several subnetworks? Perhaps even
to/from several external IPs?

Setting routers to bridge mode is something we've only glanced upon so
far, it seems to mean pretty much what it says, as in behave like a
switch and blindly relay packets. Only kink being that I didn't know
until reading up now about it handling the PPP. That (I should think)
makes it rather useful.

Haven't visited yet, just had a first look, seems like another reading
session.

<puzzled>

AFAICT PPP of all versions is just a sequence of bytes, why can't
PPPoA be relayed to a host which then deals with the LCP/NCP stuff?
(Not that I can see much reason for wanting to, mind you)

Thanks, and sorry for trying to use you as a teacher..

Dave J.
--
Dave Johnson - requiem@freeuk.com

In message <okfdm01kes00mo4rb18i966a4mb7qnj37b@4ax.com>, Dave J
<requiem@freeuk.com> writes
I'll see if I can clarify any.


Remember that many of these ADSL routers have very limited routing
capabilities - quite a few are one LAN rule and one WAN rule, with the
DMZ, if implemented, being a special case on the LAN (often in the NAT
code) rather than a totally separate broadcast domain.

This is actually not true of many ZyXEL devices, which have IP alias
(the possibility of multiple LAN subnets) and static routing facilities
- but on most if not all of the Prestige ADSL routers, the firewall has
only LAN to WAN and WAN to LAN rules.

My ZyWALL 35 has 'grown up' rather - it has a full firewall, a hardware
DMZ (which also has IP alias), static routing and what ZyXEL call policy
routing (which is best read about in the manual).


These things happen.

I don't want two lots of NAT, and with most of these devices you have
the option of NAT or no-NAT, but not a mixed case. The only exception
I'm aware of is the latest series of Westell ADSL routers, though I
believe there's firewall issues in the mixed case (i.e. the firewall
doesn't apply to either the NAT or no-NAT).

There's something of a discussion of this at
<http://www.broadbandreports.com/forum/remark,11427547~mode=flat> that I
wrote - read the last post in the thread for the single IP address
cases.


I'm not CCNA, but I guess maybe the vendor bias of the course is
showing, added to which CCNA is, I believe, more about higher end stuff.
I doubt any time is spent in CCNA talking about the non-IOS
Cisco/Linksys boxes.


:-)


Overall, the ZyWALLs are pretty decent routers; I'm certainly happy with
mine.

I can't get IGMP working (BBC streaming multicast, which my ISP, Zen,
does support), but I think that's because the IGMP in the ADSL router
behind the ZyWALL is documented as not working.


Multi-NAT is NAT involving multiple external IP addresses. If you want
ZyXEL manuals, they're all on ftp.zyxel.com - downloading the user
guides can reveal a whole pile of interesting information.


Bridge mode is not very useful in the UK as PPPoA can't go over
Ethernet; it has to terminate in the device that understands ATM.

It's much more commonly used in the United States, where typically PPPoE
is used - which will go over Ethernet, allowing a remote router to
terminate the PPP session.


ZyXEL ADSL routers will allow you to terminate a PPPoA session and
bridge, but you can't make sensible use of this, not least because you
can't find out what the WAN gateway address is (as it often changes per
connection, even with static IP addresses), and that comes only in the
PPP negotiation.


PPP half bridge is the classic way, anyway.


PPPoA is PPP over ATM. I don't have deep level protocol knowledge, but
to carry it over Ethernet, I think you'd have to tunnel ATM over
Ethernet or some similar horrid mess. You can't just put ATM cells into
Ethernet frames - at least not without adding a whole pile of overhead.

I keep meaning to read the PPPoA RFC (RFC 2364).


If you do want to carry PPPoA over Ethernet, the usual way is to use one
of the handful of pieces of ADSL equipment that will either turn PPPoA
into PPPoE or PPPoA into PPTP - then you terminate the other protocol on
the main router.

Disadvantages include loss of MTU if you go for PPPoE (you can't run
1500 byte MTU over PPPoE) and possible stability issues.




David
--
David Wood
david@wood2.org.uk