Questions tagged [switching]

For questions related to traffic switching and troubleshooting the traffic switching process.

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4
votes
1answer
595 views

QoS Policing vs Shaping, why policing

Regarding QoS, we have two modes: shaping or policing. The policing drops packets while shaping put the packets in buffer. Shaping seems to be the better solution in a general ways, so, why use ...
1
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1answer
775 views

Cannot ping or SSH into new Catalyst 2960-CX switch from the server VLAN (1)

I recently setup a Cisco Catalyst 2960-CX switch at work (I'm a SysAdmin at a SMB). Our workstations use VLAN 3, but our servers use VLAN 1. The management IP of the new switch (in VLAN 3) is 192.168....
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0answers
83 views

Cisco stacking - priority and number information

In case of switches stacking, where are stored the information about the switch number and the switch priority ? After a reset, these information were conserved.
1
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1answer
405 views

Calculating buffer capacity

The serialization delay is the amount of time it takes to forward bits out of an interface. A 1 gigabit per second interface can send 1 billion bits per second. One billion bits per second equates to ...
3
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2answers
985 views

Does it make sense to map a VLAN to each LAN?

I saw a picture of a network-structure with VLANs in it: Why would somebody structure their network like this? Does this even make sense? I mean, they are in a different LAN, why then mapping a VLAN ...
2
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1answer
1k views

Really basic SG300 VLAN setup not working

My understanding of VLANs may need improved, but isn't the idea that you can run multiple LANs at layer 2 level over the same router if VLANs are setup correctly on the SG300? If so, I fail to see how ...
2
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1answer
111 views

Spanning tree behaviour - topology change

Regarding a next change we have to do, we are studying spanning tree behaviour. Does the following statement is true ? In the case of topology change, if a new BPDU is received: Currently: Root ...
0
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1answer
45 views

What switching methods do SOHO switches use, like in cisco switches used?

Switching methods like, Store and Forward Cut-Through Fragment-free
2
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0answers
136 views

Cisco: Routing issue between LANs [closed]

We have a project to create 3 offices, which are 3 different LANs where the configuration should be as follows: Each Office should have 1 printer, where the office is able to print They should be ...
1
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1answer
315 views

How to create vlan for admin?

I wanted create a separate vlan for admin and give access to other vlan , so what is the procedure or method to do it?
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2answers
1k views

Gratuitous arp and unicast flooding

we have few 100s of access switches connecting to a core 10k in IRF. Here all our access is pretty much dumb does only L2 job. So what happens now is unicast flooding, technically MAC ages out, ...
2
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1answer
458 views

Frame relay, PVC and DLCI

Regarding the frame relay technology, could you confirm to me that traffic using permanent virtual circuit use the same ISP routers in the path for all packets sent ? I'm a little bit confused. Frame ...
5
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1answer
203 views

Cisco Catalyst Line Cards - memory considerations

Do the Catalyst Line Cards (4500 and 6500 series) hold memory (kept after reload), or some other information independently of the Supervisor Card? I ask regarding a chassis reset process, in order to ...
0
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2answers
207 views

Can a switch segregate traffic that is before the switch from after the switch?

Per the question, Lets try to clarify a bit. Can a switch that has a router connected to it, segregate traffic (using a VLAN) from traffic that is part of the modem/router the switch is connected to? ...
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2answers
118 views

Setting up a hypervisor network

I have a pfsense appliance that serves as my router. I have four hypervisors that I want to hook up to one of the router interfaces through a switch. The hypervisors will house multiple VMs that are "...
1
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2answers
12k views

Solving Native Vlan Mismatch error

I am new in VLANs , im currently trying to complete this topology however i can see the following errors on all the three switches: EX: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered ...
3
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2answers
563 views

Control plane terminology - Cisco Nexus

Is it true to speak about layer 2 control plane (LACP, STP, etc), and layer 3 control plane (OSPF, EIGRP, etc) ? or do we have only a general control plane ? We know Cisco Nexus vPC cluster has a ...
2
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2answers
2k views

What does ethernet switch do with IP address [closed]

Sorry about asking stupid question here but I'm very new to this field... Here is my current set up: _____ NAS | Modem --- Router --- Server |____ ...
4
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3answers
1k views

Theoretical: Bottleneck in a switch stacking environment

Quick question regarding stacking environments and their limitations regarding traffic bottlenecks. Assuming the following use case: We have a stack of 8 switchs, forming a Half 10Gbps stack ring. ...
1
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2answers
903 views

Endpoint MAC address change detection [closed]

A question regarding a host behavior when gateway mac address has changed (although it deals with Windows, I think it's the best forum). Assuming a windows host sending trafic to a destination IP, ...
6
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3answers
3k views

Is there any reason to use a hub over a switch?

Given that hubs are essentially the same as switches, as far as I know, except they share bandwidth between all connected devices, while switches do not, resulting in faster connections. I am simply ...
1
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1answer
294 views

Isolating a NAS using VLANS and netwgear layer 2 switches

I have a NAS which is used locally by a computational cluster that I would like to isolate from the corporate network. I have a netgear GS752TXS that connects the various nodes of the cluster as well ...
1
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2answers
285 views

CSMA/CD - CSMA/CA switch mix

Suppose I have 2 switches; one CSMA/CA (gigabit) and the other CSMA/CD (gigabit), would they work together when connected and if so would there be any dip in network performance? Thanks in advance!
3
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1answer
322 views

How would I configure etherchannel for this particular topology?

How would I setup and configure etherchannel from switch0 to all the other switches? Switch0 has been configured as the root bridge, Router0 has been configured to be the gateway for each Vlan and as ...
3
votes
1answer
755 views

Cisco MLS and MQC QoS - trust cos/dscp

A question about Cisco MLS and MQC QoS. I read two things on a Cisco guide: https://www.cisco.com/c/en/us/support/docs/switches/catalyst-3850-series-switches/118629-technote-qos-00.html On the ...
2
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1answer
1k views

MLS QoS to MQC conversion

Currently trying to convert MLS QoS to MQC QoS, I'm facing a problem. In MLS (3750), and auto QoS we have this configuration for INPUT QUEUES: mls qos srr-queue input bandwidth 90 10 So in input 90% ...
1
vote
1answer
240 views

Can you vlan tag and assign a priorty (0-7) to SCP traffic

My question is in relation to the file transfer protocol SCP. I have a local time sensitive network built. In time sensitive network you can give priority to traffic by vlan tagging and assigning ...
3
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2answers
110 views

Intermittently loose communication with upstream managed switch

I have a network for a small company that has been running without an issue for a few years. We have Cisco IP phones on VLAN 100 and computers on VLAN 1. The VLANS are auto assigned by the Cisco ...
3
votes
1answer
3k views

Best Practice for Connecting 3 Switches to Router

I am wondering the best way to connect 3 switches to a router in a server rack. The router is a Cisco RV320 (Dual Gigabit with two static IPs) There is three 48-port Ubiquiti EdgeSwitches, A Datto ...
3
votes
3answers
361 views

What is likely to occur with the frames addressed to x, if x is disconnected from the switch. then reconnected on another link?

I don't see how this could be a problem, as the switch table would remember the destination MAC address. My teacher says this is a problem and that the switch would need to reconfigure. could you ...
4
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1answer
298 views

MAC ACL to prevent access to unauthorized computers

My company wanted to prevent rogue PCs from being connected to our network. Network access must be allowed only for our company users and specifically for PCs, Printers.. that are provided by the ...
2
votes
1answer
53 views

Should igmp table lookup misses flood to all ports?

With igmp snooping, upon receiving a multicast packet it looks up the table and decides which ports to forward the packet. What I'm wondering is, if there is not an entry in the table for that ...
4
votes
1answer
255 views

CAM/RAM switch memory

Someone could explain to me the following statement, just read in Cisco Press ? CAM is significantly faster than RAM, as it searches the entire memory content in one cycle, instead of a single ...
3
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3answers
2k views

Switching methods (CEF, hardware, software, TCAM table)

Currently studying the switching methods, someone could confirm to me the assumptions as follows ? I also would have some questions. Generally the layer-2 switches have ASIC components with CAM ...
7
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1answer
721 views

Router benefits in 2018 compared to a L3 Switch

What are the benefits nowadays to use a Router instead of a L3 Switch ?
2
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1answer
96 views

What does a LAN switch do if hosts are/are not in the same LAN?

If some host sends a frame to another one that is not in the same LAN, a the frame arrives to a LAN switch, what does it do? I believe it would broadcast it, but I'm not sure about it. And what if ...
1
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1answer
37 views

modify network paths in lab

Assume a physical switch with the following physical or virtual nodes connected to it (we are talking about a lab environment): "client" at 192.168.1.1, it sends requests to 192.168.1.2 "server1" at ...
2
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3answers
2k views

Native VLAN question

Regarding the Native VLAN role (example, VLAN 1 by default for Cisco), we often can read that: The untagged frames arriving on a trunk port, are "put" in the Native VLAN The untagged frames arriving ...
6
votes
3answers
1k views

Does a switch always get a MAC address from a PC?

I was wondering if there is a possibility that a switch won't get the needed MAC address to it's CAM. For example, if the used protocol is UDP, where the sender doesn't need an answer back from the ...
2
votes
1answer
334 views

VXLAN ingress replication limitations?

I've been trying to search for data on the scaling figures of the various network ASICs with regards to the maximum number of remote VTEPs they can handle when doing ingress-replication (a.k.a. Head-...
3
votes
2answers
172 views

Pinging And Accessing Computers On 1 Switch with 2 VLANs

I have a 16 Port Black Box switch running 2 VLANs. Switch is setup to administer on VLAN 1 (default) at 192.168.1.52 (255.255.255.0.). Ports are as followed: Ports 1 - 10: VLAN 1 (Untagged) PVID 1 ...
3
votes
2answers
410 views

MSTP - different VLAN mapping in different regions

Regarding MSTP, is it possible to have different VLAN mapping for different regions ? Example: Region 1: Instance 1: VLAN 10,20,30 Instance 2: VLAN 40,50,60 Region 2: Instance 1: VLAN 10,50,60 ...
1
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2answers
123 views

Firewall has only one port. How can I properly NAT to ISP on a Layer-3 switch?

My firewall, an iptables Linux box only has one Ethernet port. My network topology is pretty simple and looks something like this: ISP (Port Gi 1/1) -> Switch <-Firewall on Port Gi 1/2 ...
1
vote
1answer
769 views

Route Specific Traffic To Another Firewall

I'm looking for a way to setup a route from my internal LAN to another router. Here's the current situation: I have an ASA5512-X where all servers are connected and all the employees are connected to,...
1
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3answers
691 views

Traceroute inside a per packet load balancing based infrastructure

Could you confirm that in an infrastructure configured with "per packet" load balancing on the Routers (same route same metric), the usage of traceroute become unusable ? In this case the ...
1
vote
1answer
517 views

Switches gets unreachable then reachable automatically [closed]

I am currently facing an issue that for a remote site few switches gets unreachable and then reachable after sometime (could be 1 - 2 days) from a specific IP of a subnet whereas always reachable from ...
0
votes
2answers
1k views

How do two routers (from two different entities) talk to each other?

Let's say there are two routers and they are neighbors, but administered by two different organizations/entities, running two different routing protocols. How are they able talk to each other?
2
votes
1answer
278 views

Proper network design for office use

I have two 4G LTE router modems in my office which we want our clients connect to these modems to have access to the internet. I have a shared server which should connect to these both modems that ...
2
votes
3answers
2k views

Can VLANs with same no but on different switches communicate with each other?

If i have a VLAN (say VLAN 10) on switch 1 and again a VLAN 10 on switch 2. Can the hosts on these VLANS communicate with each other?
1
vote
1answer
999 views

Force10 MXL switch port mapping

I'm having trouble understanding how blade server internal NIC mapping on the Dell m1000e enclosure when using the Force10 MXL blade switch? So as I understand when two MXL Switches is inserted into ...

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