IP Debug Commands

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Router Simulator Debug Commands - Notes

Debug ip rip:

1.   Only one debug command at any given time
2.   Default timer is 30 sec.
3.   Routes received by the router (from directly connected routers only) are displayed.
4.   Routes sent by the router (to directly connected routers using broadcast address only) are displayed.
5.   16 hops inaccessible will show only if a router learns of a network that is 15 hops away from the neighbor router. That route is tagged as inaccessible.
6.   Connected RIP networks with hop count needs to be maintained for each router.
7.   Whatever routes are learnt from a neighbor should not be propagated back to the same neighbor. In other words, if a route is learnt from a particular interface, it should not be broadcast on the same interface.
8.   If the network is not classful, then sending network number is to be preceded with ?subnet?
9.   To receive any debug information packets on an interface, the interface should be up.


RIP timers:

Update Timer ? 30 sec

Route Invalid timer: 180 sec ( 3 time update) The router marks a route as invalid after the invalid timer expires. If a new route is learnt before or after the invalid timer expires, the Hold down timer starts. The packets are forwarded to old inaccessible route till the Invalid timer expires.

Hold down timer ? 180sec The new route is not announced for a period of 180sec (hold down time).

Flush timer ? 240 sec This is the time that a router takes to flush out the route that had been marked as inaccessible.

http://www.livinginternet.com/i/iw_route_igp_rip.htm

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2. Debug ip eigrp:

1.   Default metrics metrics used are bandwidth and delay
2.   The debug commands provides updates when there is a change (a route is down or a new route is inserted)
3   The lowes bandwidth is used
4   Fixed delay model is used
5   Compute metric as given in this page: http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0080094cb7.shtml
6.   Take BW and delays for Fast Ethernet, Gigabit Ethernet, Serial, ISDN, WAN (Low speed serial) like FR. Extract from:
https://learningnetwork.cisco.com/thread/6116

7.   Routes are announced only when a new route inducted or a route is taken out.
8.   Typical output is shown here:
supportforums.cisco.com/thread/2006643