Computer Info IFH, Jan. 1998 Updated Nov. 2001

server 'bigbang' in F66 - new network topology

Ray Ballisti, March 1999 updated Nov. 2001

Content:

1) Network topology

2) What to change on a PC in order to take advantage of the new topology

3) How a computer know where to send data

4) (obsolete)What has been done in ETZ G60.5 on Febr 25, 1999

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1) Network topology

Our present (Nov. 2001) network looks like this

network	location	machines
129.132.20.0	G and K floor	SUNs and IBMs, 100 Mbps
129.132.20.128	G and K floor	PCs and Laptops

Our file server "bigbang" has a separate connections to each sub-networks:

     ETH network:  129.132.xx.nn     IFH network:  129.132.20.nn

   |------------------------------------------|    subnet 129.132.20.128
      |       |             |        |             netmask 255.255.255.128 
    .20.129   |           ...clients....           PCs net (K + G floor)
    router    |    
      |       |       SUN fast network (100 Mb/s)
      | ______|     |---------------------------|   subnet 129.132.20.0  (K-floor)
      | |                |       |     |        |   netmask 255.255.255.128
      | |                ..      ..clients..    |    
      | |                                       |
      | |           |---------------------------|   subnet 129.132.20.0  (G-floor)
      | |               |      |      |       |
      | |               |     .. clients ..   |      
      | |               |                   .20.1
      | |       . [qfe1]| .20.45            router
      | |       ====================          |
      | |       ||  bigbang-mwel  ||          |
      | | [qfe2]||                ||          |    <-- server "bigbang" 
      | |________|                ||          |           in ETZ F66
      |  .20.160|| bigbang-mwel-pc||          |
      |         ||                ||          |
      |         ||                ||          |
      |         ||       bigbang  ||          |
      |         ===============_====          |    <-- main entry port from outside
      |         129.132.2.214  |[hme0]        |     
      |                        |              |         
      |   dept. network .2.192 |              |    
      |                        |--jabba       |    
      |                        |--drwho       |
      |                        |--router      |
      |                        -    | .2.193  |    
      |   subnet 129.132.2.192      |         |
      |   for spec. mach. in Dept.  |         | 
      |   netmask 255.255.255.192   |         |
      |                             |         |
      |                             |         |
      |                             |         | 
  =====================================================  backbone (world)


bigbang will NOT work as a router!!

/etc/hostname.hme0 (bigbang)
(port qfe0 unused)
/etc/hostname.qfe1  (bigbang-mwel)
/etc/hostname.qfe2  (bigbang-mwel-pc)
(port qfe3 unused)

/etc/notrouter   (empty file as a flag for no routing)


root@bigbang:~# netstat -rn

Routing Table:
  Destination           Gateway           Flags  Ref   Use   Interface
-------------------- -------------------- ----- ----- ------ ---------
129.132.2.192        129.132.2.214         U        3  10691  hme0
129.132.20.0         129.132.20.45         U        2  94925  qfe1
129.132.20.128       129.132.20.245        U        2  20205  qfe2
224.0.0.0            129.132.2.214         U        3      0  hme0
default              129.132.2.193         UG       0  37949  
127.0.0.1            127.0.0.1             UH       0  70924  lo0

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2) What to change on a PC in order to take advantage of the new topology

(This information has been put together with the help of Federico Bonzanigo)
If you are trying to contact "bigbang" your PC will transmit the data to the router because it does not know that "bigbang" can be reached directly. Below are the instructions (supposing you are using MS Windows NT) in order to teach your PC that "bigbang" can be reached directly. First at all you have to know on which subnetwork you are:

follows this path:
Start -> Setting -> Control Panel -> Network -> Protocol -> TCP/IP Protocol
and check your PC's IP number:

129.132.20.xx (xx less than 128) ---> you are in the SUN subnetwork. Should not! Please contact me.
129.132.20.xxx (xxx bigger than 129) ---> you are in the PCs subnetwork(good!)

All you need is to correct the "hosts" and "lmhosts" files which are in directory "\Winnt\System32\Drivers\Etc" and correct the entry for "bigbang" as follows:
129.132.20.245 bigbang bigbang-mwel-pc

IF (your PC is in PC subnet [ .20.xxx ] )
THEN
Federico has prepared the "hosts" and "lmhosts" files on "albali" in \Zip\Hosts and you only need to copy them into your PC in "\Winnt\System32\Drivers\Etc".
For LMHOSTS it is best if you use the build in copy utility:
Protocols -> TCP-IP Protocol -> WINS Address -> Import LMHOSTS (via Network Neighborhood -> albali)

ELSE
edit the files manually as follows:
129.132.20.245 bigbang bigbang-mwel-pc
ENDIF

If you have any question please feel free to ask me (2 2753) or Federico (2 5134)

3) How a UNIX computer know where to send data

Let us suppose that machine "bigbang" (which is configured as given in the previous chapter) want to send some data to machine "priamos".
From the file "hosts" or if necessary from DNS (Domain Name Service) it will get the IP address of priamos (129.132.20.73).
Using the Network Mask (in our case 255.255.255.128) determine that the network must be 129.132.20.0
From the Routing Table (see chapter 2) it sees that the network 129.132.20.0 can be reached going through 129.132.20.45 (bigbang-mwel itself) at port (interface) qfe1.
Just remember that the physical layer for the data transmission is ETHERNET, i.e. each packet of information has a head with the "ETHERNET" address of the recipient. Each ETHERNET address is unique in the world BUT does not contain any useful information about WHERE the machine is. The INTERNET address is also unique AND has a tree structure, can also be divided into DOMAINS and is very useful for routing purpose. The INTERNET address in encapsulated as data in the ETHERNET packet.
Thus having established that "priamos" is in subnet 129.132.20.0 we can aks for his ETHERNET address sending a "broadcast" message (which will be readed by all machines listening on this subnet) using the ARP protocol:

bigbang -> (broadcast) ARP C Who is 129.132.20.73, priamos?

If machine "priamos" is UP then it will get the message and gives the answer:

priamos -> bigbang ARP R 129.132.20.73, priamos is 8:0:20:9b:f2:cd

(priamos know the ETHERNET address of bigbang because it was in the broadcast packet)
Now bigbang can build ETHERNET packets using the address 8:0:20:9b:f2:cd to send data to priamos using port qfe1.

Let now suppose that bigbang want to send data to "bernina".
Again via DNS it gets the IP address of bernina (129.132.98.11).
Looking into the Routing Table it sees that it does not have access to this network (129.132.98.0). In this case bigbang will send his data to the router (see "default" in the Routing Table). It see that the router has IP address = 129.132.2.193 and thus is in the 129.132.2.192 network which can be accessed through port (interface) hme0. In order to send to the router "bigbang" will execute the same procedure as before for "priamos".
The only difference is that encapsulated in the data is a request to the router to send the packet to IP address 129.132.98.11. The router will know how to do this.

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4) Conversion of the Hub Room ETZ G60.5 (obsolete: Jan 1999)

You can read below the letter from Mr. Brundiers explaining what has been done in ETZ G60.5:

From brundiers@tik.ee.ethz.ch  Fri Jan 29 15:57:23 1999
Date: Fri, 29 Jan 1999 15:57:10 +0100

Subject: Netzunterbruch 25/26.2.99 - Umbau Kommunikationsraum G-Stock

Wann
ab Donnerstag, 25.Feb.1999, 06:00 Uhr bis ca Freitag, 26.Feb.1999 abends.
(Bei unvorhergesehenen Schwierigkeiten kann sich der Unterbruch bis ins
Wochenende hinziehen.)

Was ist betroffen
- saemtliche Netzwerkanschluesse im ETZ-G-Stock eingeschlossen die
  Raeume vom IfE und IFH auf dem G-Stock
- die direkt verbundenen Anschluesse des TIK im F- und im H-Stock.
- Saemtliche Server des Instituts TIK (tik1,tik2,kom1,spr1,syt1,tec1,
  pistache-1, pistache-2a,filemaker-server,commserver,optical-server).
- Saemtliche Kommunikationsgeraete im ETZ-G60.5 (ISDN-Anschluesse und Modems).

Was ist nicht betroffen
- Die Telefonanschlusse sind vom Umbau NICHT betroffen, d.h. es wird
  KEIN Unterbruch beim internen Telefon und beim FAX-Betrieb geben.

Warum
- Aufschaltung der zusaetzlichen UTP-Anschluesse in den Labor-Raeumen.
- Einbau der Komponenten fuer die Umstellung von 6 Subnetzen
  auf Fast Ethernet
  - tik-mac1/2
  - tik-komsys
  - tik-techinf
  - tik-sprach
  - tik-server
  - tik-studsun.
- Aufschaltung zusaetzlicher Telefonanschluesse.
- Zusammenfassung aller Kommunikationsanschluesse und Komponenten in
  einheitlichen Schraenken
  (Telefon, UTP, Glasfaser, Video, Ethernet-Hubs 10- und 100baseT,
   ATM-Switch, LocalTalk-Hubs, Swissnet-NTs, Modems)
- Bereinigung der Schrank-internen UTP- und Glasfaser-Verkabelung
- Bereinigung der Raum-internen Verkabelung.

WAS wird an diesen beiden Tagen NICHT funktionieren:
- alle UNIX-Rechner am TIK einschliesslich Studentenraeume
- E-Mail
- VPP Drucker im G-Stock
- TIK-Fileserver
- TIK-WWW-Server
- TIK-NT-Server
- Swissnet
- Dial-In auf TIK-Modems oder -Bridges
- PCs und Macs koennen NUR lokal betrieben werden.

Wer mit diesem Unterbruch Probleme hat, soll sich doch bitte sofort mit der
Dienstgruppe in Verbindung setzen. Weitere Informationen folgen.

Wir hoffen auf allgemeines Verstaendnis.
Die Dienstgruppe am TIK

=========================================================================
Hans-Joerg Brundiers
Inst. fuer Techn. Informatik u. Kommunikationsnetze (TIK), Dienstgruppe
Computer Engineering and Commun. Networks Lab, Techn. Facilities Group

Eidgenoessische Technische Hochschule (ETH) Zuerich
Swiss Federal Institute of Technology (ETH) Zuerich

Mail:   Institut TIK der ETHZ, Gloriastr.35, CH-8092 Zuerich, Switzerland
Room: ETZ-G64.3, Tel: +41-1-63-27040, Fax: +41-1-63-21036
E-Mail: brundiers@tik.ee.ethz.ch
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