Date: Thu, 15 Sep 2005 09:11:10 -0400 From: "Grant Peel" <gpeel@thenetnow.com> To: "Jerry McAllister" <jerrymc@clunix.cl.msu.edu> Cc: freebsd-questions@freebsd.org, John Oxley <john@yoafrica.com> Subject: Re: IPs , Netmasks and Broadcast. Message-ID: <008601c5b9f6$f3578620$6501a8c0@GRANT> References: <200509151256.j8FCudQ7008772@clunix.cl.msu.edu>
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Jerry, I apologise. Its late in the day for me and the email addresses are blending into one :-) Anyways, so the examples I put together are correct. Good. So I wonder why, the 1 IP I have, won't work with the real netmask, but only with the 255. One more item of note, I see in dmesg that when it tries to apply it, the message: arplookup xxx.xxx.xxx.xxx failed: host is not on local network -Grant P.S. This is a small block, only 30 ips. The other 29, including 1 with the real netmask, is on another machine working fine, right beside the machine I am referencing. ----- Original Message ----- From: "Jerry McAllister" <jerrymc@clunix.cl.msu.edu> To: <gpeel@thenetnow.com> Cc: "John Oxley" <john@yoafrica.com>; <freebsd-questions@freebsd.org> Sent: Thursday, September 15, 2005 8:56 AM Subject: Re: IPs , Netmasks and Broadcast. >> >> Thanks John, >> >> What you are saying make perfect sense based on what I've had to do in >> the >> past. Just to clarify ... >> >> Lets say I have 5 machines (which I do) >> >> And lets say I have 10 blocks of IP address from my upline (which I do) >> >> 1.1.1.1/24 >> 2.2.2.2/24 >> 3.3.3.3/24 >> 4.4.4.4/24 >> ... >> >> And, lets say that I need to set up various IPs, from each of the groups >> above, on all 5 of the servers. >> >> To keep the explanation easy to follow, I will put what I might have in >> rc.conf for each machine, Leaving out the gateway IPs as they are not >> realevent to the question...my router setting work fine. > > No, this is not what I said. I don't know if anyone else has posted > on this since then. But, > > The next two chunks below represent what I said. > > ////jerry > > Sever 1: > > hostname="machine1.mydomain.com" > defaultrouter="some ip here" > ifconfig_em0="inet 1.1.1.2 netmask 255.255.255.0" > ifconfig_em0_alias0="inet 1.1.1.3 netmask 255.255.255.255" > ifconfig_em0_alias1="inet 1.1.1.4 netmask 255.255.255.255" > ... > ifconfig_em0_alias2="inet 2.2.2.3 netmask 255.255.255.255" > ifconfig_em0_alias3="inet 2.2.2.4 netmask 255.255.255.255" > ifconfig_em0_alias4="inet 2.2.2.5 netmask 255.255.255.255" > ... > ifconfig_em0_alias5="inet 3.3.3.4 netmask 255.255.255.255" > ifconfig_em0_alias6="inet 3.3.3.5 netmask 255.255.255.255" > ifconfig_em0_alias7="inet 3.3.3.6 netmask 255.255.255.255" > ... > > Sever 2: > > hostname="machine2.mydomain.com" > defaultrouter="some ip here" > ifconfig_em0="inet 1.1.1.5 netmask 255.255.255.0" > ifconfig_em0_alias0="inet 1.1.1.6 netmask 255.255.255.255" > ifconfig_em0_alias1="inet 1.1.1.7 netmask 255.255.255.255" > ... > ifconfig_em0_alias2="inet 2.2.2.6 netmask 255.255.255.255" > ifconfig_em0_alias3="inet 2.2.2.7 netmask 255.255.255.255" > ifconfig_em0_alias4="inet 2.2.2.8 netmask 255.255.255.255" > ... > ifconfig_em0_alias5="inet 3.3.3.7 netmask 255.255.255.255" > ifconfig_em0_alias6="inet 3.3.3.8 netmask 255.255.255.255" > ifconfig_em0_alias7="inet 3.3.3.9 netmask 255.255.255.255" > ... > > > ----------------------------------------------------------------- > > Sever 1: >> >> hostname="machine1.mydomain.com" >> defaultrouter="some ip here" >> ifconfig_em0="inet 1.1.1.2 netmask 255.255.255.0" >> ifconfig_em0_alias0="inet 1.1.1.3 netmask 255.255.255.255" >> ifconfig_em0_alias1="inet 1.1.1.4 netmask 255.255.255.255" >> ... >> ifconfig_em0_alias2="inet 2.2.2.3 netmask 255.255.255.0" >> ifconfig_em0_alias3="inet 2.2.2.4 netmask 255.255.255.255" >> ifconfig_em0_alias4="inet 2.2.2.5 netmask 255.255.255.255" >> ... >> ifconfig_em0_alias5="inet 3.3.3.4 netmask 255.255.255.0" >> ifconfig_em0_alias6="inet 3.3.3.5 netmask 255.255.255.255" >> ifconfig_em0_alias7="inet 3.3.3.6 netmask 255.255.255.255" >> ... >> >> >> Sever 2: >> >> hostname="machine2.mydomain.com" >> defaultrouter="some ip here" >> ifconfig_em0="inet 1.1.1.5 netmask 255.255.255.0" >> ifconfig_em0_alias0="inet 1.1.1.6 netmask 255.255.255.255" >> ifconfig_em0_alias1="inet 1.1.1.7 netmask 255.255.255.255" >> ... >> ifconfig_em0_alias2="inet 2.2.2.6 netmask 255.255.255.0" >> ifconfig_em0_alias3="inet 2.2.2.7 netmask 255.255.255.255" >> ifconfig_em0_alias4="inet 2.2.2.8 netmask 255.255.255.255" >> ... >> ifconfig_em0_alias5="inet 3.3.3.7 netmask 255.255.255.0" >> ifconfig_em0_alias6="inet 3.3.3.8 netmask 255.255.255.255" >> ifconfig_em0_alias7="inet 3.3.3.9 netmask 255.255.255.255" >> ... >> >> Sever 2: >> >> hostname="machine3.mydomain.com" >> defaultrouter="some ip here" >> ifconfig_em0="inet 1.1.1.8 netmask 255.255.255.0" >> ifconfig_em0_alias0="inet 1.1.1.9 netmask 255.255.255.255" >> ifconfig_em0_alias1="inet 1.1.1.10 netmask 255.255.255.255" >> ... >> ifconfig_em0_alias2="inet 2.2.2.9 netmask 255.255.255.0" >> ifconfig_em0_alias3="inet 2.2.2.10 netmask 255.255.255.255" >> ifconfig_em0_alias4="inet 2.2.2.11 netmask 255.255.255.255" >> ... >> ifconfig_em0_alias5="inet 3.3.3.10 netmask 255.255.255.0" >> ifconfig_em0_alias6="inet 3.3.3.11 netmask 255.255.255.255" >> ifconfig_em0_alias7="inet 3.3.3.12 netmask 255.255.255.255" >> ... >> >> Server 3, 4 and 5 similar with repeating patterns. >> >> So the original question was: When setting up an IP from any given block, >> do, or should I, need to use the real netmask that my ISP has assinged me >> (for the first), then, the single host (255) netmask for each of the rest >> (Again, from a specific IP block? >> >> I hope it is because I have hundreds of IPs set up that way. >> >> The reason I ask this question (again) is because I have one IP that does >> not want to work using the above paradigm. That is to say, that it IS the >> only IP from a specific block, on a particular machine, and it won't take >> using the real netmask, it will only work using the 255 netmask. >> >> Sincerly, >> >> -Confused >> (Grant). >> >> >> >> >> >> >> >> ----- Original Message ----- >> From: "John Oxley" <john@yoafrica.com> >> To: "Grant Peel" <gpeel@thenetnow.com> >> Cc: <freebsd-questions@freebsd.org> >> Sent: Thursday, September 15, 2005 7:55 AM >> Subject: Re: IPs , Netmasks and Broadcast. >> >> >> > On Wed, Sep 14, 2005 at 12:00:12PM -0400, Grant Peel wrote: >> >> Now I am really confused. >> > First of all install ipcalc NOW. >> > >> >> Up until this morning I thought I had a good handle on when I need to >> >> use >> >> the real Netmask and Broadcast. >> >> >> >> For example, If I have 3 servers, and my upline asigns me a block of >> >> 128 >> >> addresses, for the first ip used (from this block) on each server, I >> >> would >> >> need to specify the IP, true netmask and a broadcase. Then, when using >> >> more >> >> IPs from that block, I would use a 255.255.255.255 netmask and a >> >> broadcast >> >> equal to the IP. >> > >> > No, a 255.255.255.255 netmask specifies a single host. If your ISP has >> > given you 128 IPs, that is a /25 or netmask 255.255.255.128 as shown : >> > sysjo@hades:~$ ipcalc 192.168.254.0/25 >> > Address: 192.168.254.0 11000000.10101000.11111110.0 0000000 >> > Netmask: 255.255.255.128 = 25 11111111.11111111.11111111.1 0000000 >> > Wildcard: 0.0.0.127 00000000.00000000.00000000.0 1111111 >> > => >> > Network: 192.168.254.0/25 11000000.10101000.11111110.0 0000000 >> > HostMin: 192.168.254.1 11000000.10101000.11111110.0 0000001 >> > HostMax: 192.168.254.126 11000000.10101000.11111110.0 1111110 >> > Broadcast: 192.168.254.127 11000000.10101000.11111110.0 1111111 >> > Hosts/Net: 126 Class C, Private Internet >> > >> > So all your machines would have the same network and broadcast, and you >> > would make them all use your gateway box as the default route. >> > >> > As you can see, a 255.255.255.255 netmask (/32) is only one host: >> > sysjo@hades:~$ ipcalc 192.168.254.34/32 >> > Address: 192.168.254.34 11000000.10101000.11111110.00100010 >> > Netmask: 255.255.255.255 = 32 11111111.11111111.11111111.11111111 >> > Wildcard: 0.0.0.0 00000000.00000000.00000000.00000000 >> > => >> > Hostroute: 192.168.254.34 11000000.10101000.11111110.00100010 >> > Hosts/Net: 1 Class C, Private Internet >> > >> > >> > What you need to do is use IP calc to see what the network and >> > broadcast >> > are and set those, although on FreeBSD 4.X (I think anyway, someone >> > correct me if I am wrong) you can just put in your /etc/rc.conf >> > ifconfig_bge0="inet 192.168.254.32/25" >> > or >> > ifconfig_bge0="inet 192.168.254.32 netmask 255.255.255.128" >> > >> > And FreeBSD will work out the network and broadcast for you. >> > >> >> Today, I was in this exact position where I was tring to add an (the >> >> first >> >> one one THAT machine, from that block) IP from a block that is almost >> >> completely used up on another server, and the one I was adding it to >> >> would >> >> not take it. When I tried adding it with a 255.255.255.255 netmask, >> >> and a >> >> broadcast eaqual to the amount of IPs from that block - it worked. >> > >> > Like I said before, there is only 1 IP in a /32 block, and the >> > broadcast >> > will be either a.b.c.127 or a.b.c.255 depending whether you have the >> > first or second subnet inside that class C. >> > >> > Hope this helps >> > >> > -John >> > >> > >> >> >> _______________________________________________ >> freebsd-questions@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-questions >> To unsubscribe, send any mail to >> "freebsd-questions-unsubscribe@freebsd.org" >> > > >
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