High RTT - Possible causes

[STYLIANOS DEMETRIOU]

Hi guys,

According to the below diagram, what might be causing the high RTT , where should i start the troubleshooting and which are the commands and checks i have to make in order to resolve this issue.

[John Blakley]

From the diagram with no information about how things are set up, your issue could be the PC or router negotiates at 10/h instead of 100/f.

[STYLIANOS DEMETRIOU]

Hi j.blakley thanks for your reply. This is a simple scenario router is configured to use router on a stick for inter-vlan routing, the link between router and switch is trunk. Switch uses an access port to connect to the pc and also this port is in the default vlan. Nothing special here.

I've made a research and come across the following list.

1. ping 127.0.0.1

2. ping gateway

3. ping management vlan

4) Check switch overutilization

5) use debug ip routing on the router

6) ping from router the switch management vlan

7) check the MTU size on Router and on the Switch

8) Misconfigured access list on the router.

9) Switch Flooding

10) Check the logs on router and switch.

11) Duplex mismatch

From your point of view which are the correct steps to take from the above list  and in which order, to resolve the issue

[John Blakley]

I would start with your list from bottom up. Check physical first and then work up from there.