| Author |
Message |
Robert Redelmeier
Guest
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 Posted:
Thu Sep 29, 2005 2:31 am Post subject:
Re: is a NAT device/'home router' - a router? |
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In comp.dcom.lans.ethernet James Knott <james.knott@rogers.com> wrote:
| Quote: | NAT will no longer be necessary, when IPv6 is commonly used.
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Entirely true. I will mourn the passing of IPv4 and the weak
anonymity that DHCP provides. The Internet will change.
I'm not sure the IPv6 will be adopted so very quickly.
All new routing hardware will be required and the overhead
of 128bit addresses, QoS et al is approx 10% more than IPv4.
-- Robert |
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J. Clarke
Guest
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| Posted:
Thu Sep 29, 2005 3:42 am Post subject:
Re: is a NAT device/'home router' - a router? |
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James Knott wrote:
| Quote: | Robert Redelmeier wrote:
Hardly. NAT is a pseudo-clever way of hooking networks together.
Trade the underutilized ports field for the scarce address field.
Remember, the Internet is not one network, but a network of networks.
NAT will no longer be necessary, when IPv6 is commonly used. There will
be so many addresses available, that everyone can have billions of
addresses. In fact, your MAC address will form part of your IP addresses
(yes, you
will likely have multiple addresses for each computer). It will also
eliminate the need for DHCP, as each device can determine it's own
addresses etc.
|
And of course ISPs will no longer charge for static IPs and for each
additional address. Sure they won't.
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net) |
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Guest
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| Posted:
Thu Sep 29, 2005 5:31 am Post subject:
Re: is a NAT device/'home router' - a router? |
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Wayne wrote:
| Quote: | jameshanley39@yahoo.co.uk> wrote in message
news:1127904921.081046.68950@z14g2000cwz.googlegroups.com...
If there's a routing table, what is in it? (I will speculate)
No need to speculate. Here's a sample routing table from a Linksys
broadband router made circa 2000.
Destination LAN IP Subnet Mask Default Gateway Hop
Count Interface
0.0.0.0 0.0.0.0 64.x.x.x 1 WAN
64.x.x.x 255.255.240.0 0.0.0.0 1 WAN
192.168.10.0 255.255.255.0 0.0.0.0 1 LAN
One entry for the ISP's next-hop, one entry for each directly attached
network. Simple? Yes. Small? Yes. Still a routing table, still routing
|
yes, btw, where did you get LinkSys command ref from? (note-I managed
to find DLink DSL504 here http://shadow.sentry.org/~trev/dsl50x.html)
it's interesting. My DLink DSL504 router actually doesn't list local
IPs in the routing table. I guess its NAT is implemented in the
firewall part.
There is only one entry in my router's routing table - that entry being
the default route.
192.168.0.1> ip route
route add ppp_route 0.0.0.0 82.70.237.22 00:00:00:00 1 0 1 #
MAN via ppp_device
192.168.0.1>
so, doesn't seem like much need to look up the dest ip. Doesn't look
like RIP is doing much.
If the Dest IP is its own IP, then NAT and PAT kicks in. And if it's
anything it just goes to the routing table and takes the default route,
which is out the WAN interface to the ISP's router.
But there are commands and ways in the web interface, to add entries.
THe web interface mentions 2 interfaces ISP1 and Ethernet (makes
sense).
I guess if I could disable NAT such that packets could arrive at my
router with an IP of one of my local computers, - then I could start
adding entries to the routing table.
though with NAT, and this one WAN interface for the default route
entry. The whole RIP (that seems to advertise nothing - what subnets
are connected at my end to my router, that it would advertise? None-
The one subnet that it has at my end is NATed anyway - not advertised)
and Routing Table(with the 1 default entry) seems like overkill!
But I guess it's still techically a rouiter, for its RIP and routing
table. |
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Guest
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| Posted:
Thu Sep 29, 2005 5:52 am Post subject:
Re: is a NAT device/'home router' - a router? |
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Vernon Schryver wrote:
| Quote: | In article <cKKdnSUwt7DwZKfeRVn-ug@rogers.com>,
James Knott <james.knott@rogers.com> wrote:
NAT will no longer be necessary, when IPv6 is commonly used. There will be
so many addresses available, that everyone can have billions of addresses.
In fact, your MAC address will form part of your IP addresses (yes, you
will likely have multiple addresses for each computer).
I wish that were true, but it is quite wrong.
NAT will be at least as popular when IPv6 is common as it is now.
There are still many unallocated IPv4 addresses. The IPv4 addressing
problem is much less the paltry 4 billion address space than it is the
size of default free routing tables. By many accounts IPv6 will make
the routing table size problem worse instead of better, and not IPv6
addresses are 4 times larger but because of multi-homing.
NAT has always been advertised as a global address shortage solution,
but actually installed to deal with other issues. Probably the most
common real reason for using NAT at first was laziness. Assigning and
tracking blocks of addresses is more work than single addresses. NAT
really took off as a way to avoid paying consumer-grade ISP prices for
blocks of static addresses.
Note also that IPv4 DHCP and PPP IPCP are tuned for automatically
assigning single addresses instead of blocks. Maybe in theory IPv6
neighbor discovery wouldn't have the same problems, but I wouldn't
count on that in practice.
Then there is the legacy problem. What is an easier way for a DSL
or cable-modem ISP to deploy IPv6 than new "modem" firmware that
uses NAT to connect consumer IPv4 LANs to the ISP's IPv6 network?
NAT is like VHS tape and the automobile, arguably evil but very difficult
to get rid of once they're popular.
(Why follow-up to comp.dcom.lans.ethernet? NAT is more on-topic for
comp.protocols.tcp-ip than comp.dcom.lans.ethernet.)
|
mainly because on comp.dcom.lans.ethernet there were many post on
ther that clarified that a (layer 2) switch is a marketting term for a
bridge with >2 ports. And a layer 3 switch is amarketting term for a
router. So, I thought it was likely that thess home routers were only
marketted as routers, so seemed closely related to many threads in that
newsgroup. Turns out they are routers, use a routing protocol. |
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Guest
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| Posted:
Thu Sep 29, 2005 6:00 am Post subject:
Re: is a NAT device/'home router' - a router? |
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Rick Jones wrote:
| Quote: | In comp.protocols.tcp-ip Patrick Schaaf <mailer-daemon@bof.de> wrote:
NAT is NAT.
I thought it went 'NAT is evil' :)
As I recall it:
*) devices that operate at the physical layer (eg electrical/optical)
are repeaters (a "hub" being a multi-port repeater :)
*) devices that operate at the data-link layer (eg MAC) are bridges
(a "switch" simply a multi-port bridge :)
*) decices that operate at the network layer (eg IP) are routers
*) devices that operate at the transport layer and higher are gateways
Now, when you create eierlegendwolmilchsau (*), layer-blurring devices
such as firewalls and NATs you basically toss a grenade into the works
and knuth only knows what to call it besides "bletch."
rick jones
|
coudl you refer me to any book on this? I have some network book but
none breka it down as clearly as that.
I have read something about gateways connecting NWs of dissimilar
protocols or architectures. But, architecture are layer 1 and 2 too. So
the distinction between router and gateway doesn't seem tobe being able
to operate at the transport layer and application layers.
I haven't even heard of other devices at layer 3 that aren't routers.
And I haven't heard of a router without a routing protocol. (or routing
table).
Is all this addressed in one or several books?
thanks |
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James Knott
Guest
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| Posted:
Thu Sep 29, 2005 6:04 am Post subject:
Re: is a NAT device/'home router' - a router? |
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Robert Redelmeier wrote:
| Quote: | In comp.dcom.lans.ethernet James Knott <james.knott@rogers.com> wrote:
NAT will no longer be necessary, when IPv6 is commonly used.
Entirely true. I will mourn the passing of IPv4 and the weak
anonymity that DHCP provides. The Internet will change.
I'm not sure the IPv6 will be adopted so very quickly.
All new routing hardware will be required and the overhead
of 128bit addresses, QoS et al is approx 10% more than IPv4.
|
It's already in use in Asia and the U.S. government has made support for it
mandatory in a couple of years. Also, Linux routers can already handle it
and I'd imaging Cisco etc., should be able to with a software upgrade, if
they're not already able to. There are other advantages, besides the
larger address sizes. Standard size headers make routing easier, along
with improved QoS support and others. As I mentioned in another note, IP
addresses include the MAC addresses. This means that as soon as a device
is powered up, it already has a local network address. It will then find
out what networks it's on, to determine other IP addresses. No need for
DHCP or arp. |
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James Knott
Guest
|
| Posted:
Thu Sep 29, 2005 6:06 am Post subject:
Re: is a NAT device/'home router' - a router? |
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J. Clarke wrote:
| Quote: | NAT will no longer be necessary, when IPv6 is commonly used. There will
be so many addresses available, that everyone can have billions of
addresses. In fact, your MAC address will form part of your IP addresses
(yes, you
will likely have multiple addresses for each computer). It will also
eliminate the need for DHCP, as each device can determine it's own
addresses etc.
And of course ISPs will no longer charge for static IPs and for each
additional address. Sure they won't.
|
According to what I've read, they won't be able to give out individual
addresses. Instead, customers get a fairly large block (at least 48 bits),
because the last 48 bits of your IP address are the same as your MAC
address. This means that no more than 80 bits can be assigned by the ISP,
to a subscriber. |
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Rick Jones
Guest
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| Posted:
Thu Sep 29, 2005 6:12 am Post subject:
Re: is a NAT device/'home router' - a router? |
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In comp.dcom.lans.ethernet jameshanley39@yahoo.co.uk wrote:
| Quote: | Doesn't look like RIP is doing much.
|
FWIW, doesn't have to have RIP, or any routing protocol for that
matter, to be a router.
rick jones
--
The glass is neither half-empty nor half-full. The glass has a leak.
The real question is "Can it be patched?"
these opinions are mine, all mine; HP might not want them anyway... :)
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH... |
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Rick Jones
Guest
|
| Posted:
Thu Sep 29, 2005 6:42 am Post subject:
Re: is a NAT device/'home router' - a router? |
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In comp.protocols.tcp-ip jameshanley39@yahoo.co.uk wrote:
| Quote: | Rick Jones wrote:
In comp.protocols.tcp-ip Patrick Schaaf <mailer-daemon@bof.de> wrote:
NAT is NAT.
I thought it went 'NAT is evil' :)
As I recall it:
*) devices that operate at the physical layer (eg electrical/optical)
are repeaters (a "hub" being a multi-port repeater :)
*) devices that operate at the data-link layer (eg MAC) are bridges
(a "switch" simply a multi-port bridge :)
*) decices that operate at the network layer (eg IP) are routers
*) devices that operate at the transport layer and higher are gateways
Now, when you create eierlegendwolmilchsau (*), layer-blurring devices
such as firewalls and NATs you basically toss a grenade into the works
and knuth only knows what to call it besides "bletch."
rick jones
coudl you refer me to any book on this? I have some network book but
none breka it down as clearly as that.
|
I would, but I'm not sure where I 'learned' that bit - it may be
collective wisdom from ages past, or maybe something from CS244 (?)
when I was still entertaining notions of getting an MS via SITN. (I
decided to stick with my BS :)
Maybe one of the Stevens or Stallings books.
| Quote: | I haven't even heard of other devices at layer 3 that aren't
routers. And I haven't heard of a router without a routing
protocol. (or routing table).
|
All a routing protocol does is stuff things into the routing table.
One does not have to have a routing protocol going to have a "thing"
be a router.
rick jones
--
Wisdom Teeth are impacted, people are affected by the effects of events.
these opinions are mine, all mine; HP might not want them anyway... :)
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH... |
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Rick Jones
Guest
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| Posted:
Thu Sep 29, 2005 6:46 am Post subject:
Re: is a NAT device/'home router' - a router? |
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|
James Knott <james.knott@rogers.com> wrote:
| Quote: | It's already in use in Asia and the U.S. government has made support
for it mandatory in a couple of years.
|
FWIW, at one point the U.S. Government mandated that systems they
bought support OSI :)
| Quote: | Also, Linux routers can already handle it and I'd imaging Cisco
etc., should be able to with a software upgrade, if they're not
already able to.
|
You left-out that contemporary "consumer" OSes - perhaps for a fairly
broad definition back in time for "contemporary" - support IPv6.
| Quote: | There are other advantages, besides the larger address sizes.
Standard size headers make routing easier, along with improved QoS
support and others. As I mentioned in another note, IP addresses
include the MAC addresses. This means that as soon as a device is
powered up, it already has a local network address. It will then
find out what networks it's on, to determine other IP addresses. No
need for DHCP or arp.
|
Is ND really a proper superset of DHCP? I thought I heard of some
DHCPv6 stuff out there - makes me wonder if everything devices get via
DHCP they can get via IPv6 ND?
IPv6 needs a "killer app."
rick jones
--
The glass is neither half-empty nor half-full. The glass has a leak.
The real question is "Can it be patched?"
these opinions are mine, all mine; HP might not want them anyway... :)
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH... |
|
| Back to top |
|
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Guest
|
| Posted:
Thu Sep 29, 2005 7:02 am Post subject:
Re: is a NAT device/'home router' - a router? |
|
|
jameshanley39@yahoo.co.uk wrote:
| Quote: | Wayne wrote:
jameshanley39@yahoo.co.uk> wrote in message
news:1127904921.081046.68950@z14g2000cwz.googlegroups.com...
If there's a routing table, what is in it? (I will speculate)
No need to speculate. Here's a sample routing table from a Linksys
broadband router made circa 2000.
Destination LAN IP Subnet Mask Default Gateway Hop
Count Interface
0.0.0.0 0.0.0.0 64.x.x.x 1 WAN
64.x.x.x 255.255.240.0 0.0.0.0 1 WAN
192.168.10.0 255.255.255.0 0.0.0.0 1 LAN
One entry for the ISP's next-hop, one entry for each directly attached
network. Simple? Yes. Small? Yes. Still a routing table, still routing
yes, btw, where did you get LinkSys command ref from? (note-I managed
to find DLink DSL504 here http://shadow.sentry.org/~trev/dsl50x.html)
it's interesting. My DLink DSL504 router actually doesn't list local
IPs in the routing table. I guess its NAT is implemented in the
firewall part.
There is only one entry in my router's routing table - that entry being
the default route.
192.168.0.1> ip route
route add ppp_route 0.0.0.0 82.70.237.22 00:00:00:00 1 0 1 #
MAN via ppp_device
192.168.0.1
so, doesn't seem like much need to look up the dest ip. Doesn't look
like RIP is doing much.
If the Dest IP is its own IP, then NAT and PAT kicks in. And if it's
anything it just goes to the routing table and takes the default route,
which is out the WAN interface to the ISP's router.
But there are commands and ways in the web interface, to add entries.
THe web interface mentions 2 interfaces ISP1 and Ethernet (makes
sense).
I guess if I could disable NAT such that packets could arrive at my
router with an IP of one of my local computers, - then I could start
adding entries to the routing table.
though with NAT, and this one WAN interface for the default route
entry. The whole RIP (that seems to advertise nothing - what subnets
are connected at my end to my router, that it would advertise? None-
The one subnet that it has at my end is NATed anyway - not advertised)
and Routing Table(with the 1 default entry) seems like overkill!
But I guess it's still techically a rouiter, for its RIP and routing
table.
|
ah,my mistake. I didn't realise your routing table was - like mine -
as expected - not listing NAT either. You actually have 2 directly
connected networks and they aren't behind NAT. Since they are in the
routing table and the Dest IP could equal an IP on one of those
networks. I didn't have that in mind when I thoguht of a home router.
I have trouble trying to disable NAT on my home router. Your router is
certainly more router like than mine! |
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Robert Redelmeier
Guest
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| Posted:
Thu Sep 29, 2005 7:57 am Post subject:
Re: is a NAT device/'home router' - a router? |
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|
James Knott <james.knott@rogers.com> wrote:
| Quote: | It's already in use in Asia and the U.S. government has made
support for it mandatory in a couple of years. Also, Linux
routers can already handle it and I'd imaging Cisco etc.,
should be able to with a software upgrade, if they're not
already able to.
|
Yes, but each packet will take more work to process.
More header, 16 bytes of address rather than 4. That will
take upto 4x longer on 32bit routing machines.
| Quote: | There are other advantages, besides the larger address
sizes. Standard size headers make routing easier, along
with improved QoS support and others.
|
QoS? Isn't that equivalent to "drop if congested"? :)
-- Robert |
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Patrick Schaaf
Guest
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| Posted:
Thu Sep 29, 2005 8:20 am Post subject:
Re: is a NAT device/'home router' - a router? |
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James Knott <james.knott@rogers.com> writes:
| Quote: | Patrick Schaaf wrote:
My take: if it forwards IP frames, it is a router.
Actually, it's ethernet frames and IP datagrams.
|
Hmm, and what layer was 'packets', again? :)
I know my usage is a bit confused, there, so I thank you for this
correction. But I think I'm not alone, and this specific confusion
is even more widespread than the bridge/switch/router/gateway
confusion.
It's really a wonder we can all talk about the same technical reality.
Must have something to do with the extraordinary simplicity and constancy
of the basic networking functions which survived. We should all thank
the inventors of that reality, instead of confusing ourselves with words. :)
best regards
Patrick |
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J. Clarke
Guest
|
| Posted:
Thu Sep 29, 2005 8:20 am Post subject:
Re: is a NAT device/'home router' - a router? |
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|
James Knott wrote:
| Quote: | J. Clarke wrote:
NAT will no longer be necessary, when IPv6 is commonly used. There will
be so many addresses available, that everyone can have billions of
addresses. In fact, your MAC address will form part of your IP addresses
(yes, you
will likely have multiple addresses for each computer). It will also
eliminate the need for DHCP, as each device can determine it's own
addresses etc.
And of course ISPs will no longer charge for static IPs and for each
additional address. Sure they won't.
According to what I've read, they won't be able to give out individual
addresses. Instead, customers get a fairly large block (at least 48
bits), because the last 48 bits of your IP address are the same as your
MAC
address. This means that no more than 80 bits can be assigned by the ISP,
to a subscriber.
|
I'm not sure I understand why this would prevent the ISP from providing
individual addresses. Are you saying that it is technologically impossible
for them to block all MAC addresses other than those that you are paying
for the privilege of using?
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net) |
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James Knott
Guest
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| Posted:
Thu Sep 29, 2005 4:20 pm Post subject:
Re: is a NAT device/'home router' - a router? |
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|
Vernon Schryver wrote:
| Quote: | The good reason your box might support RIP is to advertise a default
route to hosts on your home network.
|
How many hosts respond to RIP? If there's only one route to the internet,
there's no need for RIP. |
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