9
votes
Accepted
Stretching VLANS across a network infrastructure
That is actually overly broad. There is nothing technically wrong with VLANs being used over a large network area as long as the network is designed properly. In modern networks, you can use more ...
- 1,951
6
votes
Stretching VLANS across a network infrastructure
However, how is it with wired devices? The access layer switches will
also connect to multiple wired devices and those devices will most
likely be in different VLANs, so again, trunks will have to get
...
- 98.4k
5
votes
If all subnets are a part of same vlan, then the network segregation using subnets does not make sense
So, does Vlan and Subnetting go hand in hand? What I meant is, if we need to use subnetting, the do we need to also make sure each subnet is part of a different vlan?
In 98% of the cases, YES. You ...
- 66.9k
4
votes
Accepted
Cannot get inter-VLAN routing to work
You need to set up a static route on the ISP router for 192.168.55.0/24 (or 192.168.0.0/16 already) via 192.168.1.2. Without that route, any IP address not from 192.168.1.0/24 (attached locally) is ...
- 81.6k
4
votes
Accepted
Static route is not saved - Why?
On ISP1, you have configured 209.165.240.13/30 on interface Serial0/1/0. That interface doesn't seem to be up or even exist (see routing table), so the static route via 209.165.240.14 cannot become ...
- 81.6k
4
votes
Why does this access list block DHCP request?
DHCP Discover broadcast has to be whitelisted explicitly
ip access-list extended MITARBEITER
permit udp host 0.0.0.0 eq bootpc host 255.255.255.255 eq bootps
permit TCP 10.15.240.0 0.0.0.255 any
...
- 305
4
votes
Accepted
Cisco interface vlan (shutdown vs no ip address)
IPv4 is not the only layer-3 protocol. We have IPv6, and Cisco has supported others, too.
You could, for example, have something like this:
interface Vlan10
no ip address
ipv6 address 2001:db8:1234:...
- 98.4k
4
votes
Can we have two logging source-interface configured on Cisco Switch?
No. You can have only one source interface statement. If you try to add the second, it will simply overwrite the first.
- 66.9k
4
votes
Non VLAN Tagged Traffic Not Going Through Trunk Between Cisco Switches
You set the interface native (untagged) VLAN to VLAN ID 1 and then only allowed VLAN 79 on the Trunk interface so untagged packets (VLAN 1) cannot pass over it. Add VLAN 1 to the allowed VLAN list on ...
- 1,951
3
votes
Accepted
A newbie question about VLAN
You are mixing port-based and tagged VLANs, which is generally fine. It's important to understand the common terminology though:
a port in access mode connects a single untagged VLAN to an end device ...
- 81.6k
3
votes
Accepted
How to implement inter-vlan routing in this configuration on L3 switch
When IP routing is enabled (global ip routing command) on the layer-3 switch, it will default to route between the layer-3 SVIs. There is no reason to configure a different interface to be able to ...
- 98.4k
3
votes
Accepted
Is non-blocking per-VLAN (rapid) spanning tree configuration possible?
Short answer: no.
RSTP is entirely VLAN agnostic, so there's no way to make both trunks forwarding, regardless of which VLANs they use.
You need either RPVST+ or MSTP on both switches, then you can ...
- 81.6k
3
votes
Accepted
VTP VLAN configuration not allowed when device is not the primary server for vlan database
I got it. I rebooted the switch but the Primary Server role is not reboot-persistent, which means it may be lost if the switch reloads and another one taking over the Primary Server role.
You can make ...
- 79
3
votes
Accepted
Communication between different VLANs
there is no way to communicate between two VLANs using only layer 2.
That is correct.
VLANs can communicate with other VLANs when they both use the same trunk link to connect to the same layer 2 ...
- 81.6k
3
votes
VLANs vs subnets pros and cons
VLANS and subnets normally go hand in hand. That is there is usually a 1:1 mapping between subnets and VLANs.
It's possible to run multiple subnets on the same VLAN and it's possible to split a subnet ...
- 13k
3
votes
Accepted
ethernet switching table is empty | vQFX | EVE-NG
This is a common misunderstanding when using vQFX and Eve-NG.
For context, most virtualized Juniper devices use a VM for the Routing Engine (RE) and a VM for the FPC (line card), which are in turn ...
- 7,044
3
votes
Accepted
HSRP and DHCP problem
You haven't mentioned the equipment in use and you have not said clearly that the layer 3 switch is acting as the DHCP server but you seem to indicate that is the case.
I can be pretty sure that in ...
- 1,951
3
votes
Accepted
Give internet access with a not VLAN enabled router to two VLAN networks
Connecting a VLAN to a device without tagging support requires a dedicated, untagged port ("access").
In reverse, a device without VLAN support can only use a single, untagged VLAN on each ...
- 81.6k
2
votes
Cisco 2960 not receiving dhcp from the router
Given that this question was asked 4 years ago, I must assume that it has been resolved by now.
Still, here is my take:
I am assuming that you need the Vlan90 SVI on each switch to get an IP address. ...
2
votes
Accepted
Can Traffic pass a trunk if its not allowed but set as native vlan?
No. Only the VLANs in the VLAN allowed list will pass. In fact, the Cisco security best practices recommend not using VLAN 1 (the default VLAN), not using a native VLAN, and restricting the VLANs ...
- 98.4k
2
votes
Accepted
Cisco C9300 Drop Out And VLAN Table Loss
So the issue was each switch as acting like its own VTP server. The switch would reach out to a non existent VTP server and drop its vlan.dat. The fix we have for this was to change the VTP to ...
- 461
2
votes
Communication between different VLANs
All these statements are incorrect or at least wildy incomplete.
1.VLANs can communicate with other VLANs when they both use the same trunk link to connect to the same layer 2 switch.
No. VLAN ...
- 8,739
2
votes
Communication between different VLANs
In my previous understanding, there is no way to communicate between
two VLANs using only layer 2.
Correct
1.VLANs can communicate with other VLANs when they both use the same trunk link to connect ...
- 19.4k
2
votes
vlan forwarding
If you mirrored the uplink port and that is an 802.1q trunk, you'll have to find out if (or make sure that) ...
the port mirror configuration replicates both tagged and untagged frames over to the ...
- 8,739
2
votes
Accepted
Cisco radius auto vlan assignment without ISE
Yes, you can do it with NPS, since ISE is just fancy RADIUS server. But the details of NPS configuration should be asked on Server Fault
- 66.9k
2
votes
Accepted
Is source source_wildcard-mask necessary when traffic is orginating from a VLAN when access list is applied in direction of the interface (in)
Since the traffic is checked when leaving the vlan in direction to the
interface, can I use permit TCP any destination
destination_wildcard-mask instead of TCP source source_wildcard-mask
destination ...
- 98.4k
2
votes
MST - multiple instance design in single region
There are some things to watch out for here:
I would suggest to manually assign root priorities for the instances you're using, including the IST
Be aware that any VLAN you create after making the ...
- 186
2
votes
Accepted
MST - multiple instance design in single region
Yes, MSTIs need to be identical across a region in order to work. The configs are hashed and if the hashes don't match the instances won't work.
When the MSTIs more or less cover the same area - as in ...
- 81.6k
2
votes
Accepted
Private vlan split in two networks
There's no need to share a VLAN across those two sites - all addressing is unambiguous and a routed link will work nicely. It's a model case for a VPN tunnel.
I'd suggest setting up an IPsec tunnel. ...
- 81.6k
2
votes
Accepted
Cisco Switch vIOS-L2 in GNS3 and CCNA 200-301
That feature is not available in the L2 version. You need the L3 version.
- 66.9k
Only top scored, non community-wiki answers of a minimum length are eligible