I assume that you are referring to 3com 4900 switch.
Here is some information I could find. Please do further research on both the products
3Com 4900 switches are incapable of classifying or reclassifying data on a per port basis as well as any data-specific criteria. These switches simply honor the 802.1p CoS tags and offer no intelligence to do the tagging or change the tagging within the switch. This "solution" is not secure or scalable because it is totally reliant on NICs and their associated software to do all of the network's priority decision making. This implementation requires all NICs in a network to be 3Com NICs. In the event of a software bug, software upgrade, or policy change, all NICs in the network must be upgradeda very time-consuming process.
Additionally, this implementation is very prone to rogue users changing policy settings for all data transmitted from their stations.
Cisco QoS strategy is much different and much more practical than that of 3Com. The intelligence necessary to classify and reclassify data is at the switch level and accomplished in hardware. The Catalyst 3550-12T offers superior Layer 2 through 4 QoS features to ensure that network traffic is classified, prioritized, and congestion is avoided in the best possible manner. Packet classification allows the network elements to discriminate between various traffic flows and enforce policies based on Layer 2 802.1p CoS field and/or Layer 3 Differentiated Services Code Point (DSCP). Classification and reclassification can be based on criteria as specific as the IP or MAC source and destination or the Layer 4 TCP/UDP ports. Control plane and data plane ACLs are supported on all ports to ensure proper policing and marking on a per packet basis.
The SuperStack 3 4900 also falls short of the Catalyst 3550-12T when comparing how each switch handles priority traffic. The four egress queues of the 3Com SuperStack 3 4900 are hard-coded to specific CoS valuesresulting in limited flexibility for the network administrator. Additionally, the SuperStack 3 4900 implements the most limited form of schedulingstrict priority scheduling. This type of scheduling may lead to the starvation of the lower priority queues and the dropping of all best efforts traffic. Lastly, 3Com offers no support for congestion avoidance controls such as Weighted Random Early Detection (WRED). The lack of QoS support on the SuperStack 3 4900 clearly makes this switch unsuitable for environments that experience or may experience congestion as the user base grows or applications demanding more bandwidth become relevant.
The Catalyst 3550-12T supports four egress queues per portand these may be custom-tailored to the CoS ranges appropriate for a specific network. Contrary to the SuperStack 3 4900, the Catalyst 3550-12T performs advanced scheduling and congestion control. With Weighted Round Robin (WRR) scheduling, the Catalyst 3550-12T ensures that the lower priority packets are not entirely starved for bandwidth and are serviced without compromising the priority settings administered by the network manager. In conjunction with scheduling, the Catalyst 3550-12T supports congestion control via WRED. WRED avoids congestion by setting thresholds at which packets are dropped before over-congestion occurs.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.