Cisco Catalyst 3750 connected to Cisco ASA 5505 and dropping packets
- by Bo102010
(Cross posted from Super User per suggestion there)
At the office, I have inherited a network that I am still trying to fully comprehend. I have a problem today with a new connection between:
A port on a Cisco Catalyst 3750 [WS-C3750G-48TS-S running C3750-IPSERVICESK9-M version 12.2(53)SE1]
A port on a Cisco ASA 5505 [ASA Software version 8.3(2)]
The 3750 is home to a Vlan that has a few ports assigned to it.
interface Vlan3
description Internal network (172.18.160.0/24)
ip address 172.18.160.1 255.255.255.0
I have a host (outside of my control) that needs to be in this VLAN (i.e it must have an address 172.18.160.something/24) that also needs to access the Internet.
To accomplish this, I ran a link from the Catalyst (Gi1/0/13) to the ASA (Ethernet 0/5). I configured the Catalyst port like so:
interface GigabitEthernet1/0/13
description To ASA, 172.18.160.69
switchport access vlan 3
switchport mode access
speed 100
duplex full
I configured the ASA like so:
interface Vlan1
nameif inside
security-level 100
ip address 172.18.160.69 255.255.255.0
interface Ethernet0/5
speed 100
duplex full
Then I plugged the host into Ethernet 0/4 on the ASA and instructed its owner to make its default gateway 172.18.160.69. I made a NAT rule in the ASA and set up some rules, and it's able to access the Internet without issue.
However, I noticed that the Catalyst reports a ton of packets being dropped toward the ASA.
Catalyst3750#show interfaces GigabitEthernet 1/0/13 | include counters|drops
Last clearing of "show interface" counters 00:28:13
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 136909347
This is a huge number of drops, since there's not much traffic on this VLAN at all.
I tried these things:
Make sure speed and duplex agree on both sides (100 Mbps / Full)
Set no cdp enable on the Catalyst Gi10/13
Set no keepalive on the Catalyst Gi10/13
Checked for excessive CPU usage on both
Checked for excessive traffic on both
Am I missing something? Any help would be appreciated.
