Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Routing issue. EIGRP/Static's Vlans... eek

First, I have minimal experience with Routing Layer3.

Just some Vlan Layer3 stuff, but nothing like this...I'm sure some of you recognize me from some Vlan, HSRP, and port-security stuff...

I notice when I try to get to this 228.5 address, it takes

quite a while. Here is the tracert:

C:\Documents and Settings\sk>tracert 200.1.228.5

Tracing route to 200.1.228.5 over a maximum of 30 hops

1 1 ms 1 ms 1 ms 200.2.131.1

2 <1 ms <1 ms <1 ms 200.2.129.37

3 1043 ms 627 ms 648 ms 10.22.103.2

4 617 ms 710 ms 630 ms 200.1.225.246

5 651 ms 620 ms 624 ms 200.1.225.245

6 661 ms 637 ms 642 ms 200.1.228.5

7 * * * Request timed out.

8 * ^C

Yet when I tracert 228.2 in the same network, I get:

C:\Documents and Settings\sk>tracert 200.1.228.2

Tracing route to 200.1.228.2 over a maximum of 30 hops

1 1 ms 3 ms 1 ms 200.2.131.1

2 <1 ms <1 ms <1 ms 200.2.129.36

3 <1 ms <1 ms <1 ms 200.1.228.2

4 1 ms <1 ms <1 ms 200.1.228.2

Trace complete.

That 200.2.131.1 address is VLAN12 on a Layer3 switch.

We have a few Layer3's, but this switch has the highest

standby priority...

This is a 'sh ip route' from the Layer3

LAY3#sh ip route | include 200.1.228.0

200.1.228.0/24 is variably subnetted, 3 subnets, 3 masks

S 200.1.228.0/24 [1/0] via 200.1.228.64

Now, I don't have access to the 228.64 Router, but shouldn't

this routing be done via the Layer3?

Eek, this stuff probably isn't nearly enough info for you guys

to make an educated guess. But can someone explain to me the

possible scenerios on why the tracert would take two different paths for two different IP's in the same network?

2 REPLIES
Hall of Fame Super Silver

Re: Routing issue. EIGRP/Static's Vlans... eek

You are correct that there is not enough here to really determine what is causing this. I notice that while both destination addresses may be in the same subnet that after the first hop they are taking different paths through the network. If you want to investigate this I suggest that you start at 200.2.131.1. Do more than show ip route include 200.1.228.0. It would be interesting to see the results for show ip route 200.1.228.5 and the results for show ip route 200.1.228.2.

It certainly looks like that device has multiple routes. It could be because there are static routes somewhere, it could be that there are mismatches in the subnet mask being advertised by some devices. It could be that the switch has two equal cost paths to that subnet and is doing per destination load sharing.

And you are making an assumption that both addresses are in the same subnet. In fact if some were to configure those addresses with a /30 mask (255.255.255.252) they would be in different subnets.

HTH

Rick

Cisco Employee

Re: Routing issue. EIGRP/Static's Vlans... eek

You probably have two different routing entries on 200.2.131.1. One that resolves 200.1.228.2 to a next hop of 200.2.129.36 and another one that resolves 200.1.228.5 to a next hop of 200.2.129.37.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
96
Views
0
Helpful
2
Replies
CreatePlease login to create content