21

Is it correct in assuming that ASICs for router or switch interfaces will outperform the use of an x86 CPU for all packet processing which will greatly suffer from CPU interrupts? It's hard to say specifically whether interrupts are a limitation, since we aren't naming specific CPU, operating system or router models in this part of your question. Overall, ...


12

You really, really do not want to disable STP where you connect switches to other switches. That is the entire purpose of STP. If you disable STP, and there is a problem, it will really be too late because your entire network could crash when you notice it, and recovering from a broadcast storm is no fun at all. By the way, portfast doesn't actually disable ...


11

You can use short range SFP optics for this. The Cisco part number is GLC-SX-MM, and the cost is about $75-$100 each (you'll need two). The person installing your fiber should use 50uM multimode fiber (62.5uM is also useable, but you're getting close to the maximum range) with LC type connectors.


11

tl;dr The switch management cannot send anything to a different layer-3 network without a default gateway. Telnet is a bidirectional protocol, and the switch, without the default gateway, would be unable to respond to the host which is attempting to establish the Telnet session. Long explanation: The default gateway on a switch has the same function as ...


9

You can specify an interface to receive an address from DHCP like this. configure terminal interface (int-name-num) ip address dhcp This guide gives way more detail into DHCP features - Cisco DHCP Client Configuration You should note that there are additional commands to the ones I listed, but they are optional.


9

If you didn't save the configuration, you could just restart the switch, but you will need physical access to the switch. You may be able to get someone at the site to restart the switch for you. Simply unpluuging it, waiting a few minutes, then plugging it back in should work. Also, Cisco maintains a Password Recovery Procedures web page with links to the ...


8

As you found, the port is plugged into a phone; so until the phone cycles the port will stay up. Regarding the portfast command; when a switchport comes up, spanning-tree moves through a series of states to bring the port up. Legacy spanning-tree took 15 seconds in the Listening state and another 15 seconds learning. During that time, the port cannot ...


8

Spanning tree only runs between switches, never to standard end hosts. Bear in mind that, under normal circumstances, a port supporting spanning tree will (when it first comes up) run through a sequence of first listening for BPDU's, then learning source addresses and then finally forwarding frames. This can take ~30 seconds, during which the connected ...


8

You can disregard the dedicated management interface and simply assign an IP address to the VLAN 500 interface on the switch and use this IP for management purpose, with appropriate access lists. FE0 is useful for out of band management. Nothing prevent you to perform in-band management without it.


8

I was wondering if there was a way to switch out the VLAN ID from VLAN1 to VLAN10 without impacting the connectivity of the end users? No. First, you must remove the addressing from VLAN 1 before you could put that same addressing on VLAN 10 (interfaces cannot have the same or overlapping addressing). Next, if that address is your gateway, then you will ...


7

In a word: YES. Unless you want to do something like force a 10G SFP+ to link at 1G, you don't have to do anything but plug it in.


7

Open a TAC case as these may be affected by this Field Notice. This revolves around a known memory issue by parts from a particular supplier that have a high failure rate. These parts have been included in many different platforms including many models of the 2960 line. You can find the main page discussing this issue and providing a number of field ...


7

Your subnet mask is 255.255.0.0 (also written as /16). That means the first 16 bits of the IP address define the network, and the last 16 bits are the host address. With that mask, there are 65534 possible hosts. In your case, the first 16 bits are the same. That means both IPs are in the same subnet. That's why your switch is complaining. Remember ...


7

I have a setup with dual redundant Cisco catalyst 4506-E using the WS-X45-SUP8L-E supervisor engine and two 48-port switches below it. My task is to access and modify the switch configuration. Access shall be accomplished locally only, through console port using serial cable and user/pass combo. The notion that "thou shalt not use ssh / telnet /...


7

The order of operations is important because setting the time first will result in the time being incorrect after issuing the zone commands, so what you need to do is: First, you set the regular time zone at the configure terminal prompt using: clock set timezone <standard zone> <offset> For example: clock set timezone EST -5 Then, you set the ...


7

In addition to @Zac67 answer, in the Catalyst product line, layer 3 capabilities are often unlocked by licenses. So a given switch can be layer 3 capable but, depending on the installed license, may have none, a few, or a complete set of, layer 3 features. The switch is shipped by default with the LAN BASE license (formally LAN lite), but can be either ...


6

Maybe these bugs are affecting you: CSCuj74167 (Gigabyte link from WS-C2960X-48FPD-L not coming up when using GLC-SX-MM) applies to you. Fixed in software release 15.0(2)EX4. CSCul88801 (1G or 10G in uplink ports of a Catalyst 2960x stack may not come up after a reload or OIR of SFP/SFP+. 1G or 10G SFP appear as “unknown” in the output of the show int ...


6

This is not a fix but a workaround to get your switch boot up. It did worked on my 2960G. WS-2960G has a reset switch SW2 that hasn't been soldered (see picture). By shorting those two soldering points couple times I managed to boot the switch correctly. It appears that the affected memory will not initialize immediately after the switch is powered, but ...


6

Yes, but this might be platform dependent. For example, on Cisco 4900M: 4900M#show mac address-table count MAC Entries for all vlans: Dynamic Unicast Address Count: 8507 Static Unicast Address (User-defined) Count: 130 Static Unicast Address (System-defined) Count: 18 Total Unicast MAC Addresses In Use: 8655 Total Unicast ...


6

I want to know the appropriate cable type between: Layer-2 and Layer-3 switch Layer-3 switch and router Is it cross-over or straight through? You need to make the distinction between MDI ports and MDI-X ports. Standard cable connects MDI to MDI-X. Crossover cable connects either MDI to MDI or MDI-X to MDI-X. Traditionally both Layer-2 ...


6

That depends on how the access point is configured. If it's configured as a router you'll only see one address of the access point itself, but if it's configured as a bridge between the wireless and the wired network, you'll see a MAC address for every connected client.


6

And now the real question: To shape all unclassified egress traffic to fit into 50 Mbps, can I just enter srr-queue bandwidth shape 0 2 0 0 on the interface in question and be done? It seems like the queue sharing and shaping limits aren't guaranteed, so I might need to shape down to a nominal 45 Mbps on the egress queue if any burst over 50 Mbps ...


6

The ethernet standard (IEEE 802.3) calls the large frames damaged because the bits where the FCS is supposed to be don't match the CRC of the bits coming before them. What you see the Cisco switch do is correct for the default. Some vendors have adopted Jumbo Frames, and what you see on the servers is the use of those. Unfortunately, there is no actual ...


6

I understand that this is an incorrect configuration, but what was blocking traffic to the new switch? Is this part of the port channel or spanning tree or something else? Nothing was actually "blocking" the traffic to the new switch, the traffic was simply being forwarded to the wrong switch. This is normal operation of ports that are part of a LAG. The ...


6

Sounds like a nice job of a botched content ot the boot variable - possibly the config file variable. The switch: prompt you see there is called the ROMMON prompt. ROMMON is a bit like the BIOS of a PC, but a lot simpler. Your switch seems to fall back into bootloader/rommon continously because something after the bootloader phase is failing. The most ...


6

Your SSH client is saying "we can't agree on the cipher: server wants X but I'm configured not to speak X". This is a completely general SSH problem, not specifically related to this model of switch, which is that the SSH clients are regularly changed, usually to disallow older, weaker, ciphers. This isn't about key length, it's about cipher algorithms. ...


6

If you are using eight classes, then you are probably overthinking it. You want most traffic to be in the default class, protect real-time traffic with a priority class and policing, make sure that things like bulk transfers cannot hog your links, have a class for control traffic, and, possibly, a class for special applications. Once you hit six classes, you ...


6

The problem is not the traffic from the server to the switch, but the return traffic, from the switch to the server. Since the VLAN is native, the switch will sent the traffic for this VLAN untagged, while the server expect it tagged. So this cannot work as is. You should probably use this VLAN only for PXE boot and configure your server Operating ...


6

We don't know the configuration of your servers and PCs - which is off topic here. Portfast allows the switch ports to transition their spanning-tree mode to forwarding immediately. Without Portfast, the port must go through the spanning-tree states (down, listening, learning, forwarding). Presumably, some test that Windows does times out before the ports ...


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