About Jimsim

Jimsim is an application that emulates several routers connected via virutal networks. You can connect to the routers with your own favorite telnet program.

Connecting to the Virtual Routers

Use your favorite telnet program to connect to each of the virtual routers. For example:

  For router 1 type:
   C:>telnet localhost 10000
  For router 2 type:
   C:>telnet localhost 10001
  For router 3 type:
   C:>telnet localhost 10002

Currently the network is configured like this:

access-list [1-99] [permit/deny] [ ip wildcard-mask | host a.b.c.d | any ]
ip acccess-list [standard] [name]
ip access-group
show access-list
show ip interface
show ip interface brief
debug interface <>
encapsulation [hdlc,ppp] (serial interfaces only)
bandwidth
clock rate (serial interfaces)
interface loopback0

User commands:
 ?
 enable
 exit
 ping ip
 show cdp
 show cdp neigh
 show cdp neigh detail
 show interface
 show interface e0,eth0,etc
 show ip route
 show version

Enable commands:
 clear counters
 clear counters interface
 config terminal
 copy running startup
 copy startup running
 debug all
 debug ip routing
 debug ip eigrp
 debug cdp
 disable
 exit
 reload
 show run
 show startup
 show ip eigrp neighbors
 show ip eigrp topology
 traceroute ip
 undebug all
 undebug ip routing
 undebug ip eigrp
 undebug cdp

Config commands:
 cdp run
 enable password password
 end
 hostname 
 banner motd delimiter
 banner exec delimiter
 banner login delimiter
 ip route network netmask dest
 interface e0,eth0,etc
   bandwidth value
   ip address addr netmask
   description
   cdp enable
   shutdown
 line con0, console0, console 0
   login
   login local
   password passwd
 router eigrp number
   network a.b.c.d
 service password-encryption
 user username password password
 


 Current Limitations/Bugs

The EIGRP support is very basic. Just the network command for now.
(Neighbors don't expire.) You can disable EIGRP with "no router eigrp process_id"

The routing table isn't 100% correct. It doesn't summarize
subnets. Nor does it understand multiple routes to the
same destination. This will be fixed in the next version.

Traceroute seems to count extra hops. It's counting
each remote interface on a router as a hop. So, when
you traceroute from router1 to router3, it counts
router2 twice (once for 192.168.1.2 and 10.1.1.1)

Help support isn't all there.

Command completion sorta works.. so does the ?


Sample Usage


Say you wanted to learn about CDP and how it works. Well, start Jimsim and open a telnet 
connection to each router. Then run the command show cdp neighbors on each router.
You should how each router sees it's neighbor routers.


Now, you can disable cdp or shutdown the interfaces on Router2. Wait a few seconds for the CDP
information to timeout. (show cdp command will tell you the timeouts). Then re-run the show 
cdp neighbors and you should see the output change.


Other commands you can try, some basic routing (static and eigrp).


I'll be adding a page of "learning exercises" in a few months.




Future Features
                      
Features coming to future releases:



accesslist support 

RIP support

"PCs" - the ability to add a PC device ona network to
        test pings and applications (http,etc)

Config files - the network topology will be determined by the user.

Routing  - metrics and multiple route support

eigrp  - full eigrp support

fast ethernet interfaces 

loopback interfaces

serial interfaces with sub-interface support (hdlc + ppp)

frame relay switches

logging/syslogging

route redistribution (rip/eigrp/static)

OSPF

BGP  

vlans 

switch support (emulate a 3550)

                      

                      
                      

Jimsim is free to use for Personal use only. Corporate customers must contact me for permission.