The new network segment of troubleshooting record is slow to access the Internet.

Failure phenomenon:

Customers respond to the addition of a new internal network segment, the Internet speed of this network segment is very slow, and it takes a long time to open the web page!

Customer network environment:

Troubleshooting process:

After learning that the customer added a new network segment on the D-SW-A, the Internet speed of the following PC is very slow. After being tested at the customer site and replaced with the original network segment, the Internet speed immediately returns to normal. It's not scientific!

Log in to D-SW-A to check the switch configuration and find that there is no problem, and the new network segment OSPF is declared normal. Log in to Core-A, use sh ip route to discover that Core-A can learn the routing of new network segments, check the Core-B and firewall in turn, and find that there is no problem with the routing.

Once again look at the user network environment, users here have two exits, one is the operator 1G exit, the other is the internal network. Two links to do load balancing, usually can surf the Internet!

Since there is no problem with routing, then check from the exit!

On the PC, the gateway of the PING operator and the gateway of the internal network (the interface address of router A) are found to be connected. But what's the problem?

Test again on PC, use the tracert command for route tracking, after many tests, it is found that when using the new network segment, if the packet takes 1G exit, then there is no problem with access to the Internet. If the packet is on the internal network, it will arrive at router B.

It seems that the problem may be on router B, contact the relevant personnel, log in to router B and find that there is no route referred to by the new network segment on router B. Manually specify an anaphora route, test again, and find that the network is normal.

Summary:

The problem finally appears on the route, but think about it, if there is only one exit, then the problem may be easy to judge. It is precisely because of the current user's network environment that the user is able to access the Internet, but the Internet is slow. Users do load balancing on the firewall, and the firewall will judge which path to the destination at a certain time is the best, that is, one minute, the firewall may decide that it is the fastest to take the 1G exit, but the next minute, the firewall may judge that the internal network is the fastest! So in the end, there was a situation reflected by the user.

At this point, the fault has been solved.