05-07-2009 10:27 AM - edited 03-06-2019 05:36 AM
I have 6 links to a neighbor router.
All links are equal cost, operational and passing traffic.
When I traceroute to the next hop loopback address, traceroute ONLY uses 3 of the six paths.
ANYONE know why?
OER-Master1#sh ip eigrp top
IP-EIGRP Topology Table for AS(90)/ID(172.26.3.1)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 172.26.0.14/32, 1 successors, FD is 128256
via Connected, Loopback0
P 172.26.0.15/32, 4 successors, FD is 130816
via 172.26.2.2 (130816/128256), GigabitEthernet0/0.2
via 172.26.4.2 (130816/128256), GigabitEthernet0/0.4
via 172.26.5.2 (130816/128256), GigabitEthernet0/0.5
via 172.26.6.2 (130816/128256), GigabitEthernet0/0.6
via 172.26.1.2 (130816/128256), GigabitEthernet0/0.1
via 172.26.7.2 (130816/128256), GigabitEthernet0/0.7
OER-Master1#traceroute 172.26.0.15
Type escape sequence to abort.
Tracing the route to 172.26.0.15
1 172.26.6.2 0 msec
172.26.5.2 4 msec
172.26.4.2 0 msec
OER-Master1#
Solved! Go to Solution.
05-07-2009 11:21 AM
Hello Franck,
4 paths is the default for EIGRP
have you added
router eigpr ASN
maximum-paths 6
otherwise only 4 successors are installed in the routing table
in other words
until you don't see all 6 paths in the ip routing table with sh ip route you cannot be sure they are all used.
Hope to help
Giuseppe
05-07-2009 10:42 AM
Hello Franck,
traceroute defaults to use three probes for each TTL so it cannot discover 6 paths.
you need to use extended traceroute and to modify the number of probes sent to a number >= 6 to see this.
that is
traceroute
Hope to help
Giuseppe
05-07-2009 11:12 AM
Hi Giuseppe,
I did not know this fact.
Excellent THANKS.
I could only get the Cisco IOS to use 4 links. Since this is new IOS in a lab environment and not critical -YET, I will accept the results for now.
BTW, I specified 6, 12, 24 and 100 probes and received the same results.
IOS on Cisco 3845 router.
flash:c3845-advipservicesk9-mz.124-11.XJ4.bin"
OER-Master1#traceroute
Protocol [ip]:
Target IP address: 172.26.0.15
Source address: 172.26.0.14
Numeric display [n]:
Timeout in seconds [3]:
Probe count [3]: 100
Minimum Time to Live [1]:
Maximum Time to Live [30]:
Port Number [33434]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Type escape sequence to abort.
Tracing the route to 172.26.0.15
1 172.26.4.2 4 msec
172.26.2.2 0 msec
172.26.6.2 0 msec
172.26.5.2 4 msec *
172.26.2.2 0 msec
172.26.6.2 0 msec
172.26.5.2 4 msec
172.26.4.2 0 msec *
172.26.6.2 0 msec
172.26.5.2 0 msec
172.26.4.2 4 msec
172.26.2.2 0 msec *
172.26.5.2 0 msec
172.26.4.2 0 msec
172.26.2.2 4 msec
172.26.6.2 0 msec *
172.26.4.2 0 msec
172.26.2.2 0 msec
172.26.6.2 4 msec
172.26.5.2 0 msec *
172.26.2.2 0 msec
172.26.6.2 0 msec
172.26.5.2 4 msec
172.26.4.2 0 msec *
172.26.6.2 0 msec
172.26.5.2 0 msec
172.26.4.2 4 msec
172.26.2.2 0 msec *
172.26.5.2 0 msec
172.26.4.2 0 msec
172.26.2.2 4 msec
172.26.6.2 0 msec *
172.26.4.2 0 msec
172.26.2.2 0 msec
172.26.6.2 4 msec
172.26.5.2 0 msec *
172.26.2.2 0 msec
172.26.6.2 0 msec
172.26.5.2 4 msec
172.26.4.2 0 msec *
172.26.6.2 0 msec
172.26.5.2 0 msec
172.26.4.2 4 msec
172.26.2.2 0 msec *
172.26.5.2 0 msec
172.26.4.2 0 msec
172.26.2.2 4 msec
172.26.6.2 0 msec
--snip--
ctrl-shift 6
These are the interfaces on the next hop router where 172.26.0.15 resides.
OER-Master1#ping 172.26.1.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.26.1.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms
OER-Master1#ping 172.26.2.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.26.2.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms
OER-Master1#ping 172.26.4.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.26.4.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms
OER-Master1#ping 172.26.5.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.26.5.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms
OER-Master1#ping 172.26.6.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.26.6.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms
OER-Master1#ping 172.26.7.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.26.7.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms
OER-Master1#
05-07-2009 11:21 AM
Hello Franck,
4 paths is the default for EIGRP
have you added
router eigpr ASN
maximum-paths 6
otherwise only 4 successors are installed in the routing table
in other words
until you don't see all 6 paths in the ip routing table with sh ip route you cannot be sure they are all used.
Hope to help
Giuseppe
05-07-2009 11:30 AM
THANKS,
I thought the EIGRP default was 6. :(
OER-Master1(config)#router eigrp 90
OER-Master1(config-router)#maximum-paths 16
OER-Master1(config-router)#end
OER-Master1#
OER-Master1#traceroute
Protocol [ip]:
Target IP address: 172.26.0.15
Source address: 172.26.0.14
Numeric display [n]:
Timeout in seconds [3]:
Probe count [3]: 6
Minimum Time to Live [1]:
Maximum Time to Live [30]:
Port Number [33434]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Type escape sequence to abort.
Tracing the route to 172.26.0.15
1 172.26.7.2 0 msec
172.26.6.2 4 msec
172.26.5.2 0 msec
172.26.4.2 0 msec
172.26.2.2 4 msec
172.26.1.2 0 msec
OER-Master1#
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