How to calculate the flux of SPAN Port?
 

I set a span port on Cisco Catalyst 2948G ,just useing the following
command:
Console> (enable) set span 2/1-3 2/4 both inpkts enable
SPAN destination port incoming packets enabled.
Enabled monitoring of Port 2/1-3 transmit/receive traffic by Port 2/4

but,when I check the flux of 2/1-4 ports, I find the flux of port 2/4
is not sum of the flux of 2/1-3. Then Can anyone explain the reasons
to me ?thanx .

Console> (enable) show span
Status : enabled
Admin Source : Port 2/1-3
Oper Source : Port 2/1-3
Destination : Port 2/4
Direction : transmit/receive
Incoming Packets: enabled

Console> (enable) show port mac

Port Rcv-Unicast Rcv-Multicast Rcv-Broadcast
-------- -------------------- --------------------
--------------------
2/1 78813 0
1
2/2 10123 0
0
2/3 0 0
0
2/4 542 0
0
Port Xmit-Unicast Xmit-Multicast Xmit-Broadcast
-------- -------------------- --------------------
--------------------
2/1 75456 6643
815
2/2 9930 6644
816
2/3 0 0
0
2/4 174857 190
816
Port Rcv-Octet Xmit-Octet
-------- -------------------- --------------------
2/1 8172432 35120399
2/2 1117579 4393583
2/3 0 0
2/4 67902 47934366

Re: How to calculate the flux of SPAN Port?
 

wzf_cs@hotmail.com (Prfone Wang) wrote in message news:<a6dae23.0409232305.1fa8986f@posting.google.c om>...
> I set a span port on Cisco Catalyst 2948G ,just useing the following
> command:
> Console> (enable) set span 2/1-3 2/4 both inpkts enable
> SPAN destination port incoming packets enabled.
> Enabled monitoring of Port 2/1-3 transmit/receive traffic by Port 2/4
>
> but,when I check the flux of 2/1-4 ports, I find the flux of port 2/4
> is not sum of the flux of 2/1-3. Then Can anyone explain the reasons
> to me ?thanx .
>
> Console> (enable) show span
> Incoming Packets: enabled
^^^^^^^

The destination port also keeps working (at least in some some of
the time catalysts) for normal traffic on its own VLAN.
There is alo CDP, BPDU ......

Port Rcv-Unicast Rcv-Multicast Rcv-Broadcast
-------- -------------------- -------------------- --------------------
2/1 78813 0 1
2/2 10123 0 0
2/3 0 0 0
Total 1-3 10124


2/4 542 0 0


Port Xmit-Unicast Xmit-Multicast Xmit-Broadcast
-------- -------------------- -------------------- --------------------
2/1 75456 6643 815
2/2 9930 6644 816
2/3 0 0 0
85386 13287 1631

(Sum of 1-3 Tx+Rx) >> 95510 13287 1631 <<-#########
2/4 >> 174857 190 816 <<-#########

Port Rcv-Octet Xmit-Octet
-------- -------------------- --------------------
2/1 8172432 35120399
2/2 1117579 4393583
2/3 0 0
9290011 39513982

(Sum of 1-3 Tx+Rx) >> 48803993 <<-#########
2/4 67902 >> 47934366 <<-#########

Maybe CDP and BPDU are not SPANned.