i just wanna check if i need to upgrade the software or the HW of 2950 switches
i know with these switches i can trust cos or dscp and i can change the default cos-dscp map
however i have switches which is 2950 with iso version 12.1(9)EA1 and 12.1(13)EA1
when i am in config mode there is no commmand start with mls to do mls qos
even in interface level config there is no mls qos trust dscp only trust cos and device
is that becuase of ios version
% Unrecognized command
(config-if)#mls qos trust ?
cos cos keyword
device trusted device class
IOS (tm) C2950 Software (C2950-I6Q4L2-M), Version 12.1(13)EA1, RELEASE SOFTWARE
and 12.1(11)EA1 , 12.1(9)EA1 these sofware versions with those switches i have
There is one global config mls command
mls qos map ..
There are 2 interface mls commands
mls qos cos ..
mls qos trust
The "mls qos map .." command is only available with the EI image on the 2960.
The "mls qos trust .." command is available as your config shows but if you want to use the "dscp" option again you need the EI image -
first thanks jon for your quick respons
then my expectation right
because these switches directly connected to edge routers and qos is there
you know with L2 qos only and trust cos not working with uplinks to routers
then do you think better to upgrade ios ?
by the way as long we are in qos thig
i just get confudsed about something
as i know in uplink going from L2 to L3 specificaly router we need to trust based on DSCP
why when we do show mls qos maps
we see cos-to-dscp
thats mean the router capable to map cos values then we can trust the uplink as cos no only dscp???
which is not common ?
thanks again jon
The key thing to understand is that switches use an internal DCSP value to "mark" the packets as they pass through the switch.
The COS to DSCP map is used to translate a packet coming in with a COS marking to a DSCP marking that the switch uses to make QOS decisions while the packet traverses the switch.
Note that the internal DSCP value that is used by the switch is never actually written into the packet, it used purely by the switch to prioritise/queue etc. the packet.
So if you trust COS coming in then the switch uses the COS to DSCP map to derive a DSCP value that is used internally. The packet still keeps it's original COS marking.
If you trust DSCP then the internal value is the same DSCP value unless you use a DSCP mutation map.
If you don't trust the marking then the packet is given the default value on the port and this is again mapped to an internal DSCP value.
Hope this answers your question.
the thing is what you have mentioned is what i know and understand
if i trust the uplink as cos
and as i mentioned the router has cos to dscp map will the router nap this coming cos based on the map it has ?
or as i know cos when gpo to L3 wil loss its significance ?
if this is the case what is the binifit of the map in the router
is it for marking back from router to switch for example ?
Apologies for misunderstanding.
Could you just clarify when you talk of a router do you mean a layer 3 switch or a router. And is the uplink to the L3 switch/router a L2 trunk because if it isn't there won't be a COS marking in the packet.
Those are pretty old versions but if they are SI versions then you "cannot" upgrade the switch to an EI version . The switch would have to be replaced if you need those options.You should be able to tell with a show version and it will tell you if it is a SI or EI switch , hopefully its a EI . At the very least I would try to upgrade to a newer version even if its SI . 2950 all run the same code but the software is able to recognize whether it is a SI switch or EI switch and it loads the features for that particular switch and there is no way around that .
where is the SI and EI
Cisco Internetwork Operating System Software
IOS (tm) C2950 Software (C2950-I6Q4L2-M), Version 12.1(11)EA1, RELEASE SOFTWARE
Copyright (c) 1986-2002 by cisco Systems, Inc.
Compiled Wed 28-Aug-02 10:25 by antonino
Image text-base: 0x80010000, data-base: 0x80528000
ROM: Bootstrap program is CALHOUN boot loader
WES-L01-C2950-SW1 uptime is 18 weeks, 6 days, 20 hours, 1 minute
System returned to ROM by power-on
System restarted at 14:55:40 GMT Wed Aug 6 2008
System image file is "flash:/c2950-i6q4l2-mz.121-11.EA1.bin"
cisco WS-C2950SX-24 (RC32300) processor (revision C0) with 20402K bytes of memor
Processor board ID FOC0638W01H
Last reset from system-reset
Running Standard Image
24 FastEthernet/IEEE 802.3 interface(s)
2 Gigabit Ethernet/IEEE 802.3 interface(s)
32K bytes of flash-simulated non-volatile configuration memory.
Base ethernet MAC Address: 00:0A:F4:B5:A4:40
Motherboard assembly number: 73-8135-05
Power supply part number: 34-0965-01
Motherboard serial number: FOC06370YHD
Power supply serial number: PHI062800H1
Model revision number: C0
Motherboard revision number: A0
Model number: WS-C2950SX-24
System serial number: FOC0638W01H
Configuration register is 0xF
by the way what is SI and EI mean because it is customer switch i have to explain the featur as well
thank you very much
by the way if SI i need to replace it to whihc switch better with similer capabilitiers and support for EI as well ?