03-17-2006 02:08 AM - edited 03-03-2019 02:19 AM
How do I find out which route eigrp as taken to reach a particlur network, what am I looking for when I do sh ip eigrp topology ?
03-17-2006 02:43 AM
Hi Carl,
"sh ip eigrp topology" only displays feasible successors.
The routes which are present in routing table with an entry of "D" are the best route which will be used by EIGRP to reach a particular destination.
How ever if you waan a see all the entries in topology table you have to issue a command
show ip eigrp topology all-links
HTH, if yes please rate the post.
Ankur
03-17-2006 03:55 AM
Is a feasible successor a route that it could actually use ? and is says feasible distance FD
is 2816 , what does that mean ?
thanks
03-17-2006 06:03 AM
Yes,the feasability sucessor route is an alternative back up route in case the sucessor route goes down.
2816 is the cost.
The lowest cost to reach a destination is referred to as the feasible distance.
03-17-2006 06:16 AM
on this then where could i find the route that it has chosen, does sh ip eigrp top not tell me this ?
03-17-2006 06:44 AM
show ip route will show next hop or traceroute will give you hop-by-hop what you are looking for. Please rate if this helped.
Thanks!
03-17-2006 07:17 AM
so is there no command to show what routes its chosen, i thought this was possible ?
03-17-2006 08:54 AM
Hi Carl,
The routes which are chosen are the best routes and are only seen in routing table with "sh ip route" command.
There are no specific place they are stored because routing table is holding them.
In routing table for EIGRP you will see a symbol "D" which means that is the best route choosen by EIGRP and it may have a feasible successor in topology table. Incase the best route goes off the feasible successor available in topology able is then installed in the routing table.
So the best routes are available in routing table as that is the place where they should be ;)
HTH, if yes please rate the post.
Ankur
03-17-2006 11:18 AM
'show ip route eigrp' will display all eigrp routes installed in the IP routing table.
'show ip eigrp topology (net) (mask)' will display all eigrp routes learnt, that would include, successor and all feasible successors.
Take a look at the below example. 1.1.1.0/24 is installed in the routing table via the next hop address of 172.31.1.14. EIGRP topology table indicates the route being learnt from two sources, 172.31.1.14 & 172.31.1.12.
Route learnt from 172.31.1.14 is chosen as the successor because of the better metric (FD of 409600). Should this route go away, the route from the feasible successor (172.31.1.12) will become the successor.
R1#show ip route eigrp
1.0.0.0/24 is subnetted, 1 subnets
D 1.1.1.0 [90/409600] via 172.31.1.14, 00:00:53, Ethernet0/0
R1#show ip eigrp top 1.1.1.0 255.255.255.0
IP-EIGRP (AS 1): Topology entry for 1.1.1.0/24
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 409600
Routing Descriptor Blocks:
172.31.1.14 (Ethernet0/0), from 172.31.1.14, Send flag is 0x0
Composite metric is (409600/128256), Route is Internal
Vector metric:
Minimum bandwidth is 10000 Kbit
Total delay is 6000 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 1
172.31.1.12 (Ethernet0/0), from 172.31.1.12, Send flag is 0x0
Composite metric is (2195456/2169856), Route is Internal
Vector metric:
Minimum bandwidth is 1544 Kbit
Total delay is 21000 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Let me know if it helped.
--Sundar
03-17-2006 09:01 AM
sh ip route xx.xx.xx.xx (ip address of destination) will show the next hop, if a route exists otherwise the default route is used.
traceroute xx.xx.xx.xx (ip address of destination) will show ip addresses of path (providing they are not masked).
sh ip eigrp topology xx.xx.xx.xx subnetmask
will show possible first hops and their costs.
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