03-01-2025 12:05 AM
For example, there are VLANs 1 and 2 in L2, and when connection to L3 is realized in trunk mode (VLAN 1, 2 is permitted) of a single cable, is it possible for devices in VLAN 1 and 2 under L2 to communicate with each other due to the L3 routing function?
(1 for both)
Even when I looked up materials on the internet, I was only able to find a method that was realized by connecting L2 to a router, or a method where two cables between L2 and L3 are connected to each VLAN in access mode, and this was not possible even when tested with an actual machine.
(For some reason, it was possible to do it with Cisco simulations)
Actual machines I've tried:
① C9200 L3 and C1200 L2
② c3650 l3 and c1000 l2
(③ Successful simulation instruments are C3650 L3 and C2960 L2)
Things I've tried:
IP routing is enabled for L3, and both devices create VLANs, and there are no ACLs. It has also been confirmed that there are no other fixed routes.
In L3, GW (for example, set 10.10.100.1 and 10.10.200.1 to /24) within an effective NW for each VLAN, and after changing the connection port to L2 to trunk mode, VLAN 1 and 2 are permitted.
In L2, the port connected to L3 in the same way as L3 is set to trunk mode, and VLANs 1 and 2 are permitted. A PC for each VLAN is prepared, the port is set to access mode, and each VLAN is assigned, and settings within the VLAN NW (for example, 10.10.100.2 and 10.10.200.2 /24, and the default gateways are 10.10.100.1 and 10.10.200.1, respectively) are assigned to each device.
All devices are not connected to other NWs, and the PC is set to allow PING.
Confirm the SHOW command:
It has been confirmed that each VLAN has been added to the trunk settings, that all connected lines are linked up, and that two, addressed to the gateway and NW for each VLAN, have been added to the routing table.
Communication confirmation results:
As a result of sending a ping from the VLAN1 device to the VLAN2 device, a timeout occurred. The reverse is also true.
The ping from the VLAN1 device to the VLAN2 gateway is successfully passing.
Communication from the VLAN1 device to its own VLAN1 gateway is also going through.
Please let me know if there are any settings required using the method above.
Also, if anyone has had success with an actual machine with the same configuration, could you tell me the model and settings?
↓日本語
例えばL2にVLAN1,2が存在しており、L3との接続を、1本のケーブルのtrunkモード(VLAN1,2を許可)にて実現したときL3のルーティング機能によって、L2配下のVLAN1,2の機器同士が通信することは可能ですか?
(両方とも1台)
インターネット上で資料を調べても、L2とルータでの接続で実現している方法か、L2とL3の間に2本のケーブルをアクセスモードで各VLANを接続している方法しか見つからず、実機で試しても実現できませんでした。
(なぜかシスコシミュレーションだと実現できました)
試した実機:
①c9200のL3とc1200のL2
②c3650のL3とc1000のL2
(③成功したシミュレーションの機器はc3650のL3とc2960のL2)
試した内容:
L3はip routingが有効であり、両機器ともにVLANを作成し、ACLは無し。他に固定のルーティングがないことも確認済。
L3では、各VLANに有効なNW内のGW(例えば10.10.100.1と10.10.200.1を/24にして設定)を設定し、L2との接続ポートをトランクモードに変更後、VLAN1,2を許可。
L2では、L3同様にL3と接続しているポートをトランクモードにして、VLAN1,2を許可。各VLANのPCを用意しポートをアクセスモードにして、各VLANを割り当て、各機器にはVLANのNW内の設定(例えば10.10.100.2と10.10.200.2の/24、デフォルトゲートウェイはそれぞれ、10.10.100.1と10.10.200.1)を割り当てています。
他のNWには全機器繋いでおらず、PCはPINGの許可設定をしています。
SHOWコマンドの確認:
トランク設定に各VLANが追加されていることと、繋いだ線すべてがリンクアップしていること、ルーティングテーブルに各VLANのゲートウェイ宛・NW宛の2つが追加されていることを確認しています。
疎通確認結果:
VLAN1の機器から、VLAN2の機器宛にPINGを飛ばした結果、タイムアウト。逆も同様。
VLAN1の機器からVLAN2のゲートウェイ宛のPINGは無事通っています。
VLAN1の機器から自身のVLAN1のゲートウェイ宛の通信も通っています。
上記の方法で必要な設定があればご教授願います。
また、同じ構成で実機で成功したことのある方がいれば、機種と設定内容を教えて頂けますか?
Solved! Go to Solution.
03-03-2025 05:51 PM
申し訳ありません
こちらWindows FWの問題でした。
無効化で解決できたので、クローズさせて頂きます。
ご協力いただきありがとうございました。
I'm sorry
This was a Windows FW issue.
I was able to resolve it by disabling it, so I'm closing it.
Thank you very much for your cooperation.
03-01-2025 12:45 AM - edited 03-01-2025 03:53 AM
Hello @agciha
On each L2 and L3 Swirch please provide these outputs:
#sh int status
#sh int trunk
03-02-2025 06:37 PM
VLAN1,2→VLAN2,3に変更しています。
I am changing VLAN1,2 to VLAN2,3.
L3
admin#show int status
Port Name Status Vlan Duplex Speed Type
Gi1/0/1 connected trunk a-full a-1000 10/100/1000BaseTX
Gi1/0/2 notconnect 1 auto auto 10/100/1000BaseTX
Gi1/0/3 notconnect 1 auto auto 10/100/1000BaseTX
Gi1/0/4 notconnect 1 auto auto 10/100/1000BaseTX
Gi1/0/5 notconnect 1 auto auto 10/100/1000BaseTX
Gi1/0/6 notconnect 1 auto auto 10/100/1000BaseTX
Gi1/0/7 notconnect 1 auto auto 10/100/1000BaseTX
Gi1/0/8 notconnect 1 auto auto 10/100/1000BaseTX
Gi1/0/9 notconnect 1 auto auto 10/100/1000BaseTX
Gi1/0/10 notconnect 1 auto auto 10/100/1000BaseTX
Gi1/0/11 notconnect 1 auto auto 10/100/1000BaseTX
Port Name Status Vlan Duplex Speed Type
Gi1/0/12 notconnect 1 auto auto 10/100/1000BaseTX
Gi1/1/1 notconnect 1 auto auto 10/100/1000BaseTX
Gi1/1/2 notconnect 1 auto auto 10/100/1000BaseTX
Te1/1/3 notconnect 1 auto auto unknown
Te1/1/4 notconnect 1 auto auto unknown
Gi1/1/5 notconnect 1 auto auto 10/100/1000BaseTX
admin#show int tru
Port Mode Encapsulation Status Native vlan
Gi1/0/1 on 802.1q trunking 1
Port Vlans allowed on trunk
Gi1/0/1 2-3
Port Vlans allowed and active in management domain
Gi1/0/1 2-3
Port Vlans in spanning tree forwarding state and not pruned
Gi1/0/1 2-3
admin#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, m - OMP
n - NAT, Ni - NAT inside, No - NAT outside, Nd - NAT DIA
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
H - NHRP, G - NHRP registered, g - NHRP registration summary
o - ODR, P - periodic downloaded static route, l - LISP
a - application route
+ - replicated route, % - next hop override, p - overrides from PfR
& - replicated local route overrides by connected
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
C 10.10.100.0/24 is directly connected, Vlan2
L 10.10.100.1/32 is directly connected, Vlan2
C 10.10.200.0/24 is directly connected, Vlan3
L 10.10.200.1/32 is directly connected, Vlan3
L2
switch285c68#show int status
Flow Link Back Mdix
Port Type Duplex Speed Neg ctrl State Pressure Mode
-------- ------------ ------ ----- -------- ---- ----------- -------- -------
gi1 1G-Copper Full 1000 Enabled Off Up Disabled Off
gi2 1G-Copper Full 1000 Enabled Off Up Disabled On
gi3 1G-Copper Full 1000 Enabled Off Up Disabled Off
gi4 1G-Copper -- -- -- -- Down -- --
gi5 1G-Copper -- -- -- -- Down -- --
gi6 1G-Copper -- -- -- -- Down -- --
gi7 1G-Copper -- -- -- -- Down -- --
gi8 1G-Copper -- -- -- -- Down -- --
Flow Link
Ch Type Duplex Speed Neg control State
-------- ------- ------ ----- -------- ------- -----------
Po1 -- -- -- -- -- Not Present
Po2 -- -- -- -- -- Not Present
Po3 -- -- -- -- -- Not Present
Po4 -- -- -- -- -- Not Present
switch285c68#show int trunk
% bad parameter value
03-01-2025 02:15 AM
Thank you very much!
We are away from the site, so please wait 2 to 3 days for a reply about sending the results.
Best regards
03-01-2025 06:29 AM
Having difficulty following your textual description. Could you provide device configs?
In general, you should be unable to jump between VLANs unless L3 is involved routing between VLANs, which on a Cisco router or L3 switch is the default just by having interfaces defined that connect to different VLANs (i.e. there's implicit routing).
03-03-2025 05:51 PM
申し訳ありません
こちらWindows FWの問題でした。
無効化で解決できたので、クローズさせて頂きます。
ご協力いただきありがとうございました。
I'm sorry
This was a Windows FW issue.
I was able to resolve it by disabling it, so I'm closing it.
Thank you very much for your cooperation.
03-03-2025 09:58 PM
Thanks a lot for your feedback @agciha
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