cisco 3845 20% packet drop

[samarjitdas]

In my cisco 3845 router I can see output packet drop in some of the interfaces.I suspect that router is processing packet beyond its mix throughput limit. Moreover when i run show int fax/y switching command I can see packet drop by RP process. Can you please help me to troubleshoot this issue.

[Beetlejuice01]

Maybe if you post a show run, and some other information on what's ther is attached to that interface, how is configrured, on both side we can try to help you.

[samarjitdas]

This router is connected with one C2950 switch in downstream direction and with one ISP router in upstream direction. Router has five interfaces(Fe) connected with C2950 switch and they are assigned with different IP subnet. All ports of

C2950 switch are in default VLAN 1 and furtherC2950 switch is connected with 5 L3 switches. All ports of L3 switches are also in default VLAN 1 but servers are assigned with different IP pool as servers are connected to different switches.

[Beetlejuice01]

This router with 5 interface are connected all on the same switch or there are 5 switch with different ip address and subnet ? Can you send a running config of switch and router and a topology scheme?

[samarjitdas]

HI Please find the above connectivity diagram.The router with 5 interface are connected all on the same switch. All the ports of the all switches are in VLAN1. But servers are segregated with different subnets and accordingly network defined with router interface. I know, the design is not as per standard but my cencern is why output drop happening with router interface.

[Beetlejuice01]

So, you have interfaces routed connected in access on one switch, all in one broadcast domain, and the hsrp standby configuration is not in use with any other router. From design perspective is horrible. Can you put the output of drop and the interface interested in this behavior?

[samarjitdas]

Please find the attached output of show command

[Beetlejuice01]

Cdp are enabled on switch port connected and on router port?

[samarjitdas]

Yes. CDP is enabled on all ports.

[Beetlejuice01]

the 20% you refer to unknown protocol drops? because i don't see particular crc or tx/rx load. If yes are you sure on your network there aren't any other protocol than ip for example appletalk, ipx, ipv6?

[samarjitdas]

Check the line of my output: Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 3000. Here is showing output drop.

[Beetlejuice01]

Yes, i've see that, but the interface is only fa 1/12. The interface is in auto 100 auto ful? From router and switch side? Or one of interface is in half or with different speed?