Cisco IOS – How To Find VLAN IPs (SVI’s)

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KB ID 0001258 Dtd 16/11/16

Problem

If you have a complicated network, you can spend more time finding out how it's configured, than actually doing any work on it!

6500 Switch

Today I had a client that needed some changes made on their LAN, I knew their name, and their network address, and common sense told me which of the core switches they were connected to.

Solution

A quick search on the client name told me what VRF they were in, and what VLAN they were in (3000), let's have a look at that;

Petes-Core-SW#show run vlan 3000
Building configuration...

Current configuration:
!
vlan 3000
 name CORP:NET
end

That doesn't yield much more than I already know, so I can either do this and get a LOT of information;

Petes-Core-SW#show interfaces vlan 3000
Vlan3000 is up, line protocol is up
 Hardware is EtherSVI, address is c062.6be3.3000 (bia c062.6be3.9d40)
 Description: CORP:NET
 Internet address is 192.168.1.100/24
 MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
 reliability 255/255, txload 1/255, rxload 1/255
 Encapsulation ARPA, loopback not set
 Keepalive not supported
 ARP type: ARPA, ARP Timeout 04:00:00
 Last input 00:00:00, output never, output hang never
 Last clearing of "show interface" counters never
 Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
 Queueing strategy: fifo
 Output queue: 0/40 (size/max)
 5 minute input rate 254000 bits/sec, 115 packets/sec
 5 minute output rate 504000 bits/sec, 119 packets/sec
 L2 Switched: ucast: 22179333 pkt, 1561846492 bytes - mcast: 0 pkt, 0 bytes
 L3 in Switched: ucast: 471521755 pkt, 367932934560 bytes - mcast: 0 pkt, 0 bytes
 L3 out Switched: ucast: 493390206 pkt, 464908773459 bytes - mcast: 0 pkt, 0 bytes
 475554223 packets input, 366284328453 bytes, 0 no buffer
 Received 0 broadcasts (1116 IP multicasts)
 0 runts, 0 giants, 0 throttles
 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
 493591347 packets output, 462947525840 bytes, 0 underruns
 0 output errors, 0 interface resets
 0 output buffer failures, 0 output buffers swapped out

Or a more sensible;

Petes-Core-SW#show run interface vlan 3000
Building configuration...



Current configuration : 160 bytes
!
interface Vlan3000
 description CORP:NET
 mac-address c062.6be3.3000
 vrf forwarding CORP:NET
 ip address 192.168.1.100 255.255.255.0
end

Find What VLAN An IP Address Is In

If you have the opposite problem, i.e. you know the IP, (or a part of the IP). You can get the VLAN number like so;

Petes-Core-SW#show ip int br | incl 192.168.1.100
Vlan3000               192.168.1.100     YES NVRAM  up                    up

 

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Author: PeteLong

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