I've set up a 4-port etherchannel between 2 6509's, tomax and xamot (no, I didn't name them. *grin*), and then I configured the etherchannel as a trunk. Traffic seems to be going over the trunk link (boxes can connect to each other when they're on different switches), but there's something that strikes me as weird: the output of "show channel traffic" doesn't show any unicast packets going through -- it's all multicast with a smattering of broadcast. Why is that? That seems broken-ish to me, but things are working.
Here's the configuration (we're running CatOS 8.5.5 on both). Tomax:
#module 3 : 48-port 10/100/1000BaseT Ethernet set vlan 51 3/9-48 set trunk 3/5 desirable negotiate 1-4094 set trunk 3/6 desirable negotiate 1-4094 set trunk 3/7 desirable negotiate 1-4094 set trunk 3/8 desirable negotiate 1-4094 set spantree portfast 3/5-8 disable set spantree portfast 3/9-48 enable set spantree guard none 3/5-8 set port channel 3/5-8 mode desirable silent
#module 3 : 48-port 10/100/1000BaseT Ethernet set vlan 50 3/9-48 set vlan 800 3/1-4 set port speed 3/1,3/4 1000 set spantree portfast 3/5-8 disable set spantree portfast 3/3-4,3/9-48 enable set spantree guard none 3/5-8 set port channel 3/5-8 mode desirable silent
Show trunk:
Port Mode Encapsulation Status Native vlan
-------- ----------- ------------- ------------ ----------- 3/5 auto n-isl trunking 1 3/6 auto n-isl trunking 1 3/7 auto n-isl trunking 1 3/8 auto n-isl trunking 1
show channel traffic:
6509-xamot (enable) show channel traffic ChanId Port Rx-Ucst Tx-Ucst Rx-Mcst Tx-Mcst Rx-Bcst Tx-Bcst
What do you see there as actually being wrong, load balancing not more evenly spread? What balancing algorithm has been configured? If the default is still set that's "dest-mac" ... all traffic to the same destination mac will always be sent over the same channel.
Yep, that's exactly what I'm worried about. I don't know why that would be.
I'm also concerned about it being all multicast. This makes it look like there's no "regular" traffic going across these trunk links. But all machines on my network can see all other machines -- ie, I know that traffic is being passed over these trunks. If I plug 10.10.1.1 into tomax, and 10.10.1.2 into xamot, they can talk to each other just fine. Isn't that plain 'ol unicast traffic? Why are my unicast percentages at 0, then?
Maybe I'm misunderstanding unicast? It implies one-to-one; as in, a packet destined for a single machine.
Ah, good to know. I didn't know there was such a thing.
Thanks. Again, this points to my confusion: if it's all multicast traffic, then where 's traffic between, say, two machines (Like
10.10.1.1 in tomax and 10.10.1.2 in xamot) being registered in the stats?
Feels like I'm missing something here. Boxes on either switch can talk to each other, but I don't see any traffic indicated in that output. I want to *see* them talking to each other so I can confirm that it's working.
I explained why that would be ... the port-channel balancing algorithm being used ... 'dest-mac' . All 'like' multicast traffic will be sent across the same link every time. In IOS there's a 'test etherchannel' command that will show you for any given value ie. src/dst, mac/ip etc. what link of the port-channel a specific packet will be assigned. This never changes unless the normally assigned link is down.
I'd put that down to either a bug in the reporting software or that the amount of unicast traffic just doesn't have the numbers to register above 0% (seems less likely). Can you initiate a large file transfer to increase the amount of unicast traffic.
These are L2 Etherchannels by the way so you're not going to be able to configure any L3 balancing algorithms.
Use the port counters to see the traffic. It may take some time for enough traffic to cross the link to overcome the weeks of 24x7 multicasts that have been counted by the show channel traffic counters.
After some searching I found:-
show mac mod/port
This should the current counters and could be used to verify where your traffic is going.
Back to basics folks, seems you're running ISL as trunk encapsulation. Now the ISL header is multicast, so all these ISL frames on the trunk are counted multicast. Configure dot1q to get "normal" counters.
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