Show route forwarding-table explanation

[mat420]

im trying to make sense of
a.. routing table ? is it? to complete a homework question but i just dont understand can someone please explain? i sort of understand the jist of them but like, each line is another hop right> from, where to where tho? i also dont understand why 2 detinations would say default and why thered be a 0.0.0.0

im lost.
couldnt find it in the book for the life of me
also user vs perm?? ugh ;/

thanks so much

ugh i hope they let me post links

http://i16.photobucket.com/albums/b39/mat420/forwardingtable.jpg

 

[palladin9479]

Could you post the results of your routing table as text, many companies block photobucket and other meda sharing sites.

0.0.0.0 could mean a few things depending on where it shows up, if its "destination network" then it usually means a default gateway or a gateway of last resort. If a router can not find an entry in its routing table for a destination network then it'll send it over whichever path is marked with 0.0.0.0

 

[ntrceptr]

This is what the photo he posted showed.

user@router> show route forwarding-table
Routing table: inet
Internet:
Destination Type RtRef Next hop Type Index NhRef Netif
default user 0 0:17:cb:4e:ae:81 usct 520 3 ge-0/0/0.0
default perm 0 rjct 36 1
0.0.0.0/32 perm 0 dscd 34 1
172.19.0.0/16 user 0 200.1.4.100 ucst 535 3 ge-0/0/3.0
172.19.52.0/24 user 0 200.1.2.100 ucst 529 3 ge-0/0/1.0
172.19.52.16/28 user 0 200.1.3.100 ucst 534 3 ge-0/0/2.0

All I can explain is:
172.19.52.0 = a netmask
/24 = number of bits that matter
Next hop = where it should send the packet
Netif = network interface name it should use

I'm no expert in this area but have had to figure out some routing tables in the past.

 

[ntrceptr]

The spacing/tabs got discarded from the above post

 

[palladin9479]

Yeah makes reading it a headache.

That can not be a functional routing table, its missing entries. Is this for some homework or made up theoretical situation? Also is this a Juniper router? It really seems like the format a Juniper use's for its tables vs what a linux or Cisco system would use.

I'm not a Juniper expert but its looking like it does the following,

Packet destination is,
172.19.52.0/24
forward to 200.1.2.100 unicast through ge-0/0/1.0
metric 529

172.19.52.16/28
forward to 200.1.3.100 unicast through ge-0/0/2.0
metric is 534

172.19.0.0/16 forward to 200.1.4.100 through ge-0/0/3.0
metric is 535

if not in table use
0.0.0.0/32 to MAC 0:17:cb:4e:ae:81 through ge-0/0/0.0 (this is the router itself)
metric 520

But it discards any packet it doesn't know where to send it to,
default perm 0 rjct 36 1
0.0.0.0/32 perm 0 dscd 34 1

Also "user" entries are dynamically created entries from the routing daemon, usually from a neighbor router.

Whatever this is for its not getting to the internet ever, its only routing packets to those internal networks. And even then the order is off,

A packet who's destination is 172.19.52.20 should be routed out 172.19.52.16 ge-2.0, but instead it'll be routed out 172.19.52.0/24 and ge-1.0. The metrics would need to be rearranged to fit the correct order (unless ge-1.0 also services the network for ge-2.0).

 

[mat420]

THANK YOU VERY MUCH!

 

[mat420]

Best answer selected by mat420.