07-27-2010 05:50 PM - edited 03-06-2019 12:13 PM
Hi,
Can you explain the sh route in red? What path would it take to get to 10.245.65.4/30? I did a traceroute and am still confused.
TIA.
PF
sh ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is 172.31.19.1 to network 0.0.0.0
172.31.0.0/16 is variably subnetted, 9 subnets, 2 masks
C 172.31.34.0/28 is directly connected, Vlan734
C 172.31.33.0/28 is directly connected, Loopback0
C 172.31.32.0/28 is directly connected, Vlan732
C 172.31.19.0/28 is directly connected, Vlan719
R 172.31.18.0/24 [120/1] via 172.31.19.1, 00:00:26, Vlan719
R 172.31.17.0/28 [120/1] via 172.31.19.1, 00:00:26, Vlan719
R 172.31.2.0/28 [120/2] via 172.31.19.1, 00:00:26, Vlan719
R 172.31.1.0/24 [120/2] via 172.31.19.1, 00:00:26, Vlan719
R 172.31.4.0/28 [120/1] via 172.31.19.1, 00:00:26, Vlan719
R 203.18.122.0/24 [120/5] via 172.31.34.2, 00:00:25, Vlan734
10.0.0.0/8 is variably subnetted, 18 subnets, 5 masks
R 10.10.24.0/23 [120/2] via 172.31.19.1, 00:00:26, Vlan719
R 10.10.26.0/25 [120/1] via 172.31.19.1, 00:00:26, Vlan719
R 10.10.27.0/25 [120/2] via 172.31.19.1, 00:00:26, Vlan719
R 10.10.28.0/24 [120/1] via 172.31.19.1, 00:00:26, Vlan719
R 10.10.29.0/25 [120/3] via 172.31.34.2, 00:00:25, Vlan734
C 10.10.30.0/23 is directly connected, Vlan30
R 10.245.64.252/30 [120/5] via 172.31.34.2, 00:00:25, Vlan734
R 10.245.64.40/29 [120/2] via 172.31.34.2, 00:00:25, Vlan734
R 10.10.26.128/25 [120/1] via 172.31.19.1, 00:00:26, Vlan719
R 10.10.27.128/25 [120/2] via 172.31.19.1, 00:00:26, Vlan719
R 10.245.65.28/30 [120/1] via 172.31.34.2, 00:00:25, Vlan734
R 10.245.65.24/30 [120/5] via 172.31.19.1, 00:00:26, Vlan719
R 10.245.64.24/29 [120/1] via 172.31.34.2, 00:00:25, Vlan734
R 10.245.65.20/30 [120/3] via 172.31.34.2, 00:00:25, Vlan734
R 10.245.65.16/30 [120/3] via 172.31.34.2, 00:00:25, Vlan734
R 10.245.65.4/30 [120/3] via 172.31.34.2, 00:00:25, Vlan734
[120/3] via 172.31.19.1, 00:00:26, Vlan719
R 10.245.65.0/30 [120/3] via 172.31.34.2, 00:00:25, Vlan734
R 10.245.64.0/29 [120/2] via 172.31.34.2, 00:00:25, Vlan734
R* 0.0.0.0/0 [120/2] via 172.31.19.1, 00:00:26, Vlan719
R 203.18.112.0/21 [120/5] via 172.31.34.2, 00:00:25, Vlan734
traceroute
Protocol [ip]:
Target IP address: 10.245.65.5
Source address: 10.10.30.1
Numeric display [n]:
Timeout in seconds [3]:
Probe count [3]:
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 10.245.65.5
1 172.31.19.1 0 msec
172.31.34.2 0 msec
172.31.19.1 8 msec
2 10.245.64.25 0 msec
172.31.4.1 0 msec
10.245.64.25 8 msec
3 10.10.24.1 0 msec
10.245.64.1 0 msec *
07-27-2010 08:01 PM
Hello,
The routes
R 10.245.65.4/30 [120/3] via 172.31.34.2, 00:00:25, Vlan734
[120/3] via 172.31.19.1, 00:00:26, Vlan719
indicate that the RIP routing protocol is learning it via two different paths and both have equal costs. Cisco Routers support upto 4 route installations (with equal cost). If you have disabled fast switching, then the router will do per-packet loadbalancing. In this case, since the traffic is ICMP, it is automatically sent to CPU and the CPU will do loadbalancing automatically based on the routing table.
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094820.shtml
Hope this helps.
Regards,
NT
07-27-2010 10:19 PM
Nagaraja,
Thanks for the reply. If I don't want load balancing to occur, how do I ensure that it uses this path via 172.31.19.1 for instance?
Thanks.
PF
07-27-2010 10:33 PM
Hello,
You can use offset list under the RIP for that specific subnet.
access-list 1 permit 10.245.65.4 0.0.0.3
access-list 1 deny any
router rip
offset-list 1 in 3 vlan 734
exit
This will add 3 to the hop count learnt on VLAN 734 and the router will
install only the lower cost route i.e. through 172.31.19.1 (VLAN 719).
Hope this helps.
Regards,
NT
07-27-2010 11:01 PM
Nagaraja,
Thanks very much.
PF
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