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Corso GNU/Linux base '09Sun, 15 Feb 09
Anche quest'anno con l'associazione NetStudent abbiamo proposto il corso GNU/Linux base presso il Politecnico di Torino. Riporto le slide utilizzate nella seconda e terza lezione, versione rivista ed ampliata sui comandi di base, filesystem, permessi. I sorgenti sono qui disponibili.
Cisco routers and multicastFri, 23 Jan 09
Here I report some useful commands to manage and debug multicast traffic and routing using Cisco IOS network devices. In the configuration used for samples, I have 2 routers with two interfaces each one: the local one on Fa0/0 and the WAN over witch one there's a tunnel Tu0. But those commands are valid every time you need to manage multicast.

A command that shows the neighbours multicast routers. In the end you find kind of transport to reach the neighbour.
cisco# mrinfo [version  12.4] [flags: PMA]: -> [1/0/tunnel/pim] -> [1/0/pim/querier/leaf]

mstat -source IP- -destination IP- -multicast group-
Show a trace route of multicast packet with statistics. You can define source and destination address, as well as the multicast group to use:
Type escape sequence to abort.
Mtrace from to via group  
From source (?) to destination (?)
Waiting to accumulate statistics......
Results after 10 seconds:

  Source        Response Dest   Packet Statistics For     Only For Traffic   All Multicast Traffic     From 
     |       __/  rtt 52   ms   Lost/Sent = Pct  Rate     To  
     v      /     hop -42  s    ---------------------     --------------------        ? Prune sent upstream
     |     ^      ttl   0   
     v     |      hop 0    ms    -1/0 = --%      0 pps    0/0 = --%  0 pps        ? Reached RP/Core
     |      \__   ttl   1   
     v         \  hop 42   s         0         0 pps           0    0 pps   
  Receiver      Query Source

show ip mroute
Shows the multicast routing table. The table is usually dynamic, so pay attention and look at timeout values.
cisco#show ip mroute
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
       L - Local, P - Pruned, R - RP-bit set, F - Register flag,
       T - SPT-bit set, J - Join SPT, M - MSDP created entry,
       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
       U - URD, I - Received Source Specific Host Report,
       Z - Multicast Tunnel, z - MDT-data group sender,
       Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
 Timers: Uptime/Expires
 Interface state: Interface, Next-Hop or VCD, State/Mode

(*,, 2d00h/stopped, RP, flags: SJCF
  Incoming interface: Tunnel0, RPF nbr
  Outgoing interface list:
    FastEthernet0/0, Forward/Sparse-Dense, 2d00h/00:02:53

(,, 00:01:15/00:02:07, flags: PFT
  Incoming interface: FastEthernet0/0, RPF nbr
  Outgoing interface list: Null

(*,, 2d00h/00:02:00, RP, flags: SJCL
  Incoming interface: Tunnel0, RPF nbr
  Outgoing interface list:
    FastEthernet0/0, Forward/Sparse-Dense, 2d00h/00:02:00

show ip mroute active
Like before, but shows only currently transmitting multicast traffic passing through a multicast route in the router. At default, the source shown must generate at least 4kbps.
cisco#show ip mroute active 
Active IP Multicast Sources - sending >= 4 kbps
 a negative (-) Rate counts pps being fast-dropped

Group:, (?)
   Source:  (?)
     Rate: 19 pps/18 kbps(1sec), 9 kbps(last 20 secs), 14 kbps(life avg)

show ip igmp groups
To show IGMP groups present on the router and expiry times
cisco#show ip igmp groups
IGMP Connected Group Membership
Group Address    Interface                Uptime    Expires   Last Reporter   Group Accounted        FastEthernet0/0          2d00h     00:02:12       FastEthernet0/0          2d00h     00:02:19   

The next three commands are useful to debug Protocol Indipendent Multicast (PIM), usually used as a multicast routing protocol (another one more generic is NHRP).

show ip pim interface
To show interfaces involved with PIM packet protocol, with source address and destination route
cisco#show ip pim interface 
Address          Interface                Ver/   Nbr    Query  DR     DR
                                          Mode   Count  Intvl  Prior         Tunnel0                  v2/SD  1      30     1    FastEthernet0/0          v2/SD  0      30     1 

show ip pim neighbor
To show the ip address of neighbor PIM-enabled routers with interface connected to, and expiry times
cisco#show ip pim neighbor
PIM Neighbor Table
Mode: B - Bidir Capable, DR - Designated Router, N - Default DR Priority,
      S - State Refresh Capable
Neighbor          Interface                Uptime/Expires    Ver   DR
Address                                                            Prio/Mode          Tunnel0                  1d23h/00:01:34    v2    1 / B S

show ip pim rp mapping
Shows mapping between PIM group and Rendez-vous Point, eg. the IP interface of the router where you reach the multicast group.
cisco#show ip pim rp mapping
PIM Group-to-RP Mappings

Group(s):, Static
    RP: (?)
Wikipedia offlineDec 2007
Ho rilasciato il testo della mia tesi di laurea specialistica sotto licenza CC-BY-NC.
Il titolo completo e` Sviluppo di un ambiente software per la consultazione offline di Wikipedia.

E` disponibile il pdf completo e le slides annesse

La tesi verte sui metodi per ottenere una versione offline multipiattaforma di Wikipedia utilizzando software opensource; in particolare e` stato definito un meccanismo di conversione e un'interfaccia per la consultazione offline, incluso un motore di ricerca ECMAscript. Il sistema prodotto puo` essere memorizzato su diversi supporti (dvdrom, pendrive, etc) e accessibili da molti sistemi operativi senza richiedere dipendenze particolari.
Il processo e` applicabile a qualsiasi versione di Wikipedia e con poche modifiche a qualsiasi installazione di MediaWiki. Per motivi di responsabilita` in Italia l'utilizzo del software deve essere personale.
Il nome in codice del progetto e` "WaNDA", acronimo di WaNDA ancora Non Definitivamente Aggiornata. Gli applicativi prodotti sono situati su Sourceforge con il nome di WaNDA-tools: e` qui disponibile l'ultima versione del pacchetto.
GNU/LinuxNov 2007
Slides per il corso base GNU/Linux Netstudent.
Terza lezione: shell, comandi base, struttura del filesystem, permessi.
corsobaselinux_3_nov07.pdf (source)
FLOSSSep 2007
Slides on Free/Libre/Open-Source Software, in italian:
FLOSSeCO.pdf (source)

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