Interesting. Does this happen for all inter-VLAN routing, or is only a particular combination of VLANs (from-to) affected?
For a multilayer switch in elementary configuration, intra-VLAN switching shall be as effective as inter-VLAN routing. The reason for a dramatic decline in the throughput of the routed traffic is often caused by the fact that the traffic has to be processed by the CPU, instead of being routed in hardware. IP packets that cannot be routed in hardware include packets requiring fragmentation (check the MTU settings!), IP options, IP packets requiring ICMP responses and other packets that are unsupported within the CEF/TCAM infrastructure.
Try using the show cef not-cef-switched and show ip cef switching statistics commands to verify the counts of punted packets (packets sent to the CPU instead of being switched in hardware). High counts of these packets increasing intensively in time indeed suggest that the traffic is sent to the CPU. Also verify if there are any punt-type adjacencies installed in the TCAM using the show ip cef adjacency punt command - ideally, there shall be none.
Also, what is the SDM template you are using? Is there enough space in the TCAM for your IPv4 routing information? Verify it using the show platform tcam utilization to see if the "Used Masks/values" column reports a smaller usage for IPv4 routes than the "Max Masks/Values" column. If a route can not be installed into the TCAM, the packets will again be punted.
We have several VLANs, but they all have only communication with VLAN2
VLAN2 interface ip address 10.43.20.49 255.255.255.0 secondary ip address 10.43.22.49 255.255.255.0 secondary ip address 10.43.26.49 255.255.255.0 secondary ip address 10.43.21.53 255.255.255.0 no ip unreachable
If I connect a PC to gi 4/0/23 vlan 2 with direction of range 10.43.20.X and other PC to gi 4/0/24 vlan 2 with IP of range 10.43.21.X, transfer rate very very slow
If I connect a PC to gi 4/0/23 vlan 2 with direction of range 10.43.22.X and other PC to gi 4/0/24 vlan 2 with IP of range 10.43.26.X, transfer rate its good
(without level 3) --> If I connect a PC to gi 4/0/23 vlan 2 with direction of range 10.43.21.X and other PC to gi 4/0/24 vlan 2 with IP of range 10.43.21.X, transfer rate its good
If I connect a PC to gi 4/0/23 change to vlan 3 with direction of range X.X.X.X and other PC to gi 4/0/24 vlan 2 with IP of range 10.43.21.X, transfer rate very very slow
The tests tell me I'm not going to be able to do until Tuesday.
Thank you for the information you've provided. I will have to go over it more carefully. In the meantime, please, can you verify the several show commands I have suggested in my first post? These are not disruptive and can be performed anytime.
EDIT: I apologize, I did not understand you won't be able to perform those show commands until Tuesday. I apologize - no problem, we'll wait till then.
Backbone#show run int vlan 2 Building configuration...
Current configuration : 256 bytes ! interface Vlan2 ip address 10.43.20.49 255.255.255.0 secondary ip address 10.43.22.49 255.255.255.0 secondary ip address 10.43.26.49 255.255.255.0 secondary ip address 10.43.21.53 255.255.255.0 no ip unreachables
Backbone#show cef not-cef-switched % Command accepted but obsolete, see 'show (ip|ipv6) cef switching statistics [feature]'
IPv4 CEF Packets passed on to next switching layer Slot No_adj No_encap Unsupp'ted Redirect Receive Options Access Frag RP 1 0 9 0 0 0 0 0
Backbone#show ip cef switching statistics
Reason Drop Punt Punt2Host RP LES No adjacency 0 0 1 RP LES Incomplete adjacency 0 0 8 RP LES Total 0 0 9
All Total 0 0 9
Backbone#show ip cef adjacency punt Prefix Next Hop Interface
Backbone#show platform tcam utilization
CAM Utilization for ASIC# 0 Max Used Masks/Values Masks/values
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