Re: [Vyatta-users] DHCP pool questions
Exactly. Why should anybody care? This is DHCP we're talking about. As long as a node receives a currently unused address from the pool, you're up and done. If you want to control the assignment of nodes to addresses, well, that's what static addressing is for. I do think it's a bit odd that the ISC DHCP server would allocate stuff from the end of the pool rather than the beginning, but that's perfectly legal, IMO. This is just a guess, but the ISC server may be using the hash table to try to reassign the same address back to the same client if it's still available. As new clients with new MAC addresses come in, they are assigned a new address in decreasing order, but when a client returns, it will be assigned the same address as before unless another client is using it. This probably helps eliminate accidental duplicate corner cases with things like laptops that go on and off net, machines that go into a low-power sleep state, etc. In a former company, we used the standard Windows Server DHCP server and I remember having some issues with duplicate addresses being handed out. I think the server always got it right, but I think clients would sometimes miss the fact that their lease had expired. You can't completely eliminate this problem if the client is buggy, but you can mitigate it if you try to hand out the same address to the same clients each time. -- Dave _ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Aubrey Wells Sent: Sunday, January 13, 2008 9:39 PM To: Marat Nepomnyashy Cc: vyatta-users@mailman.vyatta.com Subject: Re: [Vyatta-users] DHCP pool questions From the dhcpd.conf (5) man page: quote The DHCP server generates the list of available IP addresses from a hash table. This means that the addresses are not sorted in any particular order, and so it is not possible to predict the order in which the DHCP server will allocate IP addresses. Users of previous versions of the ISC DHCP server may have become accustomed to the DHCP server allocating IP addresses in ascending order, but this is no longer possible, and there is no way to configure this behavior with version 3 of the ISC DHCP server. /quote So it looks like it is actually non-deterministic what IP you may receive. If you have a fresh dhcpd.leases file, you will initially get leases in descending order, but after a few are assigned and some are expired, it will become somewhat random(ish). This is how the ISC dhcpd daemon works (which happens to be the most popular (by far) linux dhcp daemon) and isnt specific to vyatta. If you install dhcpd on a redhat system, you'll see the exact same behavior. As for *why* this was done starting with v3 of dhcpd, I dunno. I'm curious as to why it leasing in descending order is a show-stopper for you? This seems like a (very) trivial thing to nitpick over. What difference does it make as long as your clients get addresses? -- Aubrey Wells Senior Engineer Shelton | Johns Technology Group A Vyatta Ready Partner www.sheltonjohns.com On Jan 13, 2008, at 10:41 PM, Marat Nepomnyashy wrote: Hi Mike, As far as to why the DHCP server leases out IPs from the end of the block rather than from the beginning, I'm not sure myself. I just signed up for the ISC DHCP server mailing lists at http://www.isc.org/index.pl?/sw/dhcp/dhcp-lists.php and plan to ask the people on there this question as well. If you added a second dhcp pool for eth2, but it did not appear in '/opt/vyatta/config/dhcpd.conf', and you stil have the config and the 'dhcpd.conf' after that commit, then please include these files with your message. Thanks, Marat - Original Message - From: silvertip257 mailto:[EMAIL PROTECTED] To: Marat Nepomnyashy mailto:[EMAIL PROTECTED] ; vyatta-users@mailman.vyatta.com Sent: Sunday, January 13, 2008 6:54 PM Subject: Re: [Vyatta-users] DHCP pool questions Why cannot I take addresses out of the beginning of the block like I'd rather it do? How can I (without rewriting/modifying source code)? That would really stink to have to statically assign everything to make it the way (that it makes sense). It's great and all that it actually does assign an address and ' works ', but why not start at the beginning? From what Marat wrote, I understand that you've seen that behavior before - confirmed. Now, can it be changed? I won't try to start any wars here, but that would unfortunately be one reason I would not want to use Vyatta. Well that and the WAN dhclient that's in progress. I could have sworn (oh and I did commit it) that I added a config for a second dhcp pool (separate) for eth2, but voila it's gone when I check dhcpd.conf... Thanks, Mike On Jan 13, 2008 8:37 PM, Marat Nepomnyashy [EMAIL PROTECTED] wrote: Hi Mike, As far as I know, it is normal for the ISC DHCP server that the Vyatta router is using to lease out addresses starting from the last address of the DHCP lease block, I've seen this before. Not quite sure myself why ISC
Re: [Vyatta-users] DHCP pool questions
Yeah, that makes sense. I _wish_ I had a T1 or T3 ... I'd be broke in no time and I'd never use the 24/7 bandwidth! I've got a Cisco routing/switching class this semester, so I should be able to apply most of the knowledge from that class to Vyatta and take off! You guys haven't figured out how to put Vyatta on Cisco 2811s yet have you? Then I could have Vyatta in the lab in a covert package! ;) Kidding! ;) Mike On Jan 14, 2008 8:59 PM, Stig Thormodsrud [EMAIL PROTECTED] wrote: Ok, as long as your using dhcp for an ethernet interface it should be fine. Our WAN interfaces that we support are T1 and T3 serial interfaces using ppp or hdlc or frame-relay encapsulation and those would not support dhcp client since they are point to point. stig -- *From:* silvertip257 [mailto:[EMAIL PROTECTED] *Sent:* Monday, January 14, 2008 5:54 PM *To:* Stig Thormodsrud *Subject:* Re: [Vyatta-users] DHCP pool questions What should I call my connection to my residential ISP? To me it's a WAN connection [I could be wrong] and I need dhclient running on eth0 to successfully obtain an address without ticking off my ISP (sure I can statically assign it, but they [and eventually I] will not like it) -- hehe the nature of DHCP. I'm not running PPPoE. Just DHCP back to my ISP. I'll make some nice duplications/collisions for my ISP, that could nicely coincide with Dave's Win Server DHCP conflicts! Mike On Jan 14, 2008 4:31 PM, Stig Thormodsrud [EMAIL PROTECTED] wrote: Hi Mark, I'm curious when you say WAN dhcp. Most WAN is point to point and dhcp client wouldn't really apply. Are you talking about PPPoE? stig -- *From:* silvertip257 [mailto:[EMAIL PROTECTED] *Sent:* Sunday, January 13, 2008 8:53 PM *To:* Stig Thormodsrud *Subject:* Re: [Vyatta-users] DHCP pool questions Awesome - that's what I've been reading as I sift through the emails I get from the mailing list. Mike On Jan 13, 2008 11:24 PM, Stig Thormodsrud [EMAIL PROTECTED] wrote: Ø Well that and the WAN dhclient that's in progress. Dhcp client has already been committed to the development branch which means it'll be available in the next release (glendale) assuming the testing goes well. stig -- *From:* [EMAIL PROTECTED] [mailto: [EMAIL PROTECTED] *On Behalf Of *silvertip257 *Sent:* Sunday, January 13, 2008 6:55 PM *To:* Marat Nepomnyashy; vyatta-users@mailman.vyatta.com *Subject:* Re: [Vyatta-users] DHCP pool questions Why cannot I take addresses out of the beginning of the block like I'd rather it do? How can I (without rewriting/modifying source code)? That would really stink to have to statically assign everything to make it the way (that it makes sense). It's great and all that it actually does assign an address and ' works ', but why not start at the beginning? From what Marat wrote, I understand that you've seen that behavior before - confirmed. Now, can it be changed? I won't try to start any wars here, but that would unfortunately be one reason I would not want to use Vyatta. Well that and the WAN dhclient that's in progress. I could have sworn (oh and I did commit it) that I added a config for a second dhcp pool (separate) for eth2, but voila it's gone when I check dhcpd.conf... Thanks, Mike On Jan 13, 2008 8:37 PM, Marat Nepomnyashy [EMAIL PROTECTED] wrote: Hi Mike, As far as I know, it is normal for the ISC DHCP server that the Vyatta router is using to lease out addresses starting from the last address of the DHCP lease block, I've seen this before. Not quite sure myself why ISC does it this way, maybe there is an assumption that the IPs at the end of the block are less likely to be already taken... When you write I have discovered that various parts have been separated from the main config, what do you mean? The DHCP server configuration file is '/opt/vyatta/etc/dhcpd.conf', not '/opt/vyatta/etc/dhcp.conf'. The configuration for eth2 should not show up there if you did not configure any DHCP leases for any of the subnets to which your the interface is connected. If you have additional questions, please send us snippets of your router configuration under hierarchies 'interfaces ethernet' and 'service dhcp-server'. Please also send the contents of '/opt/vyatta/etc/dhcpd.conf'. Thanks, Marat - Original Message - *From:* silvertip257 [EMAIL PROTECTED] *To:* vyatta-users@mailman.vyatta.com *Sent:* Saturday, January 12, 2008 4:36 PM *Subject:* [Vyatta-users] DHCP pool questions I've set up a complete vyatta system a few times, even with two versions ( 2.2 and 3.0). I'm currently working with 3.0 and I'm getting the same behavior as the last time. I setup a DHCP server on eth1, but when it hands out addresses, it always gives out the last address in the block (in this case
Re: [Vyatta-users] DHCP pool questions
Hi Mike,
As far as to why the DHCP server leases out IPs from the end of the block
rather than from the beginning, I'm not sure myself. I just signed up for the
ISC DHCP server mailing lists at
http://www.isc.org/index.pl?/sw/dhcp/dhcp-lists.php and plan to ask the people
on there this question as well.
If you added a second dhcp pool for eth2, but it did not appear in
'/opt/vyatta/config/dhcpd.conf', and you stil have the config and the
'dhcpd.conf' after that commit, then please include these files with your
message.
Thanks,
Marat
- Original Message -
From: silvertip257
To: Marat Nepomnyashy ; vyatta-users@mailman.vyatta.com
Sent: Sunday, January 13, 2008 6:54 PM
Subject: Re: [Vyatta-users] DHCP pool questions
Why cannot I take addresses out of the beginning of the block like I'd rather
it do? How can I (without rewriting/modifying source code)? That would really
stink to have to statically assign everything to make it the way (that it makes
sense). It's great and all that it actually does assign an address and ' works
', but why not start at the beginning?
From what Marat wrote, I understand that you've seen that behavior before -
confirmed. Now, can it be changed?
I won't try to start any wars here, but that would unfortunately be one
reason I would not want to use Vyatta. Well that and the WAN dhclient that's
in progress.
I could have sworn (oh and I did commit it) that I added a config for a
second dhcp pool (separate) for eth2, but voila it's gone when I check
dhcpd.conf...
Thanks,
Mike
On Jan 13, 2008 8:37 PM, Marat Nepomnyashy [EMAIL PROTECTED] wrote:
Hi Mike,
As far as I know, it is normal for the ISC DHCP server that the Vyatta
router is using to lease out addresses starting from the last address of the
DHCP lease block, I've seen this before. Not quite sure myself why ISC does it
this way, maybe there is an assumption that the IPs at the end of the block are
less likely to be already taken...
When you write I have discovered that various parts have been separated
from the main config, what do you mean?
The DHCP server configuration file is '/opt/vyatta/etc/dhcpd.conf', not
'/opt/vyatta/etc/dhcp.conf'. The configuration for eth2 should not show up
there if you did not configure any DHCP leases for any of the subnets to which
your the interface is connected.
If you have additional questions, please send us snippets of your router
configuration under hierarchies 'interfaces ethernet' and 'service
dhcp-server'. Please also send the contents of '/opt/vyatta/etc/dhcpd.conf'.
Thanks,
Marat
- Original Message -
From: silvertip257
To: vyatta-users@mailman.vyatta.com
Sent: Saturday, January 12, 2008 4:36 PM
Subject: [Vyatta-users] DHCP pool questions
I've set up a complete vyatta system a few times, even with two
versions (2.2 and 3.0).
I'm currently working with 3.0 and I'm getting the same behavior as the
last time.
I setup a DHCP server on eth1, but when it hands out addresses, it
always gives out the last address in the block (in this case 192.168.0.60
consistently).
When finding the configuration, I have discovered that various parts
have been separated from the main config - I don't know if it was that way in
previous versions, but thought I'd mention it.
Also, my DHCP server for eth2 does not show up in
/opt/vyatta/etc/dhcp.conf ;; that's another issue that I'll have to solve after
this one.
My config for the DHCP server:
shared-network Subnet1 {
subnet 192.168.0.32 netmask 255.255.255.224 {
not authoritative;
default-lease-time 86400;
max-lease-time 86400;
range 192.168.0.34 192.168.0.60;
}
Thanks,
Mike
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Re: [Vyatta-users] DHCP pool questions
* Well that and the WAN dhclient that's in progress.
Dhcp client has already been committed to the development branch which
means itll be available in the next release (glendale) assuming the
testing goes well.
stig
_
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of silvertip257
Sent: Sunday, January 13, 2008 6:55 PM
To: Marat Nepomnyashy; vyatta-users@mailman.vyatta.com
Subject: Re: [Vyatta-users] DHCP pool questions
Why cannot I take addresses out of the beginning of the block like I'd
rather it do? How can I (without rewriting/modifying source code)? That
would really stink to have to statically assign everything to make it the
way (that it makes sense). It's great and all that it actually does
assign an address and ' works ', but why not start at the beginning?
From what Marat wrote, I understand that you've seen that behavior before
- confirmed. Now, can it be changed?
I won't try to start any wars here, but that would unfortunately be one
reason I would not want to use Vyatta. Well that and the WAN dhclient
that's in progress.
I could have sworn (oh and I did commit it) that I added a config for a
second dhcp pool (separate) for eth2, but voila it's gone when I check
dhcpd.conf...
Thanks,
Mike
On Jan 13, 2008 8:37 PM, Marat Nepomnyashy [EMAIL PROTECTED] wrote:
Hi Mike,
As far as I know, it is normal for the ISC DHCP server that the Vyatta
router is using to lease out addresses starting from the last address of
the DHCP lease block, I've seen this before. Not quite sure myself why
ISC does it this way, maybe there is an assumption that the IPs at the end
of the block are less likely to be already taken...
When you write I have discovered that various parts have been separated
from the main config, what do you mean?
The DHCP server configuration file is '/opt/vyatta/etc/dhcpd.conf', not
'/opt/vyatta/etc/dhcp.conf'. The configuration for eth2 should not show
up there if you did not configure any DHCP leases for any of the subnets
to which your the interface is connected.
If you have additional questions, please send us snippets of your router
configuration under hierarchies 'interfaces ethernet' and 'service
dhcp-server'. Please also send the contents of
'/opt/vyatta/etc/dhcpd.conf'.
Thanks,
Marat
- Original Message -
From: silvertip257 mailto:[EMAIL PROTECTED]
To: vyatta-users@mailman.vyatta.com
Sent: Saturday, January 12, 2008 4:36 PM
Subject: [Vyatta-users] DHCP pool questions
I've set up a complete vyatta system a few times, even with two versions
(2.2 and 3.0).
I'm currently working with 3.0 and I'm getting the same behavior as the
last time.
I setup a DHCP server on eth1, but when it hands out addresses, it always
gives out the last address in the block (in this case 192.168.0.60
consistently).
When finding the configuration, I have discovered that various parts have
been separated from the main config - I don't know if it was that way in
previous versions, but thought I'd mention it.
Also, my DHCP server for eth2 does not show up in
/opt/vyatta/etc/dhcp.conf ;; that's another issue that I'll have to solve
after this one.
My config for the DHCP server:
shared-network Subnet1 {
subnet 192.168.0.32 netmask 255.255.255.224 {
not authoritative;
default-lease-time 86400;
max-lease-time 86400;
range 192.168.0.34 192.168.0.60;
}
Thanks,
Mike
--
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==
~
· ·
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// \\
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^`~´^
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Vyatta-users mailing list
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[Vyatta-users] DHCP pool questions
I've set up a complete vyatta system a few times, even with two versions (
2.2 and 3.0).
I'm currently working with 3.0 and I'm getting the same behavior as the last
time.
I setup a DHCP server on eth1, but when it hands out addresses, it always
gives out the last address in the block (in this case 192.168.0.60consistently).
When finding the configuration, I have discovered that various parts have
been separated from the main config - I don't know if it was that way in
previous versions, but thought I'd mention it.
Also, my DHCP server for eth2 does not show up in /opt/vyatta/etc/dhcp.conf
;; that's another issue that I'll have to solve after this one.
My config for the DHCP server:
shared-network Subnet1 {
subnet 192.168.0.32 netmask 255.255.255.224 {
not authoritative;
default-lease-time 86400;
max-lease-time 86400;
range 192.168.0.34 192.168.0.60;
}
Thanks,
Mike
--
// SilverTip257 //
==
~
· ·
/V\
// \\
/( )\
^`~´^
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