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title	show

You would mostly be familiar with the "show" command. It is very good and can basically be used to get output from control plane object. Most of the time this can be used against static object like config.

Let's assume that I would like to get BGP config from my home router:

Code Block

language	bash
theme	Midnight
title	show BGP configuration from running config

show running-config bgp4                                               
router bgp4 42                                                                 
 vrf dn42                                                                      
 local-as 4242421975                                                           
 router-id 172.22.105.65                                                       
 address-family unicast multicast other flowspec vpnuni vpnmlt vpnflw ovpnuni ovpnmlt ovpnflw vpls mspw evpn mdt srte mvpn omvpn
 neighbor 172.23.215.177 remote-as 4242421955                                  
 neighbor 172.23.215.177 description NOP.DN42                                  
 neighbor 172.23.215.177 local-as 4242421975                                   
 neighbor 172.23.215.177 address-family unicast multicast other flowspec vpnuni vpnmlt vpnflw ovpnuni ovpnmlt ovpnflw vpls mspw evpn mdt srte mvpn omvpn
 neighbor 172.23.215.177 distance 20                                           
 justadvert loopback42                                                         
 exit

But I can also check the status of BGP peering into VRF dn42

Code Block

language	bash
theme	Midnight
title	Check BGP IPv4 peers status in VRF dn42

show ipv4 bgp 42 summary                                               
as          learn  done  ready  neighbor        uptime
4242421955  517    518   true   172.23.215.177  00:38:18

Check the same BGP peering but now for IPv6

Code Block

language	bash
theme	Midnight
title	Check BGP IPv6 peers status in VRF dn42

r1#show ipv6 bgp 42 summary                                               
as          learn  done  ready  neighbor             uptime
4242421955  351    352   true   fd40:cc1e:c0de::151  00:40:40
show ipv4 bgp 42 summary                                               
as          learn  done  ready  neighbor        uptime
4242421955  517    518   true   172.23.215.177  00:38:18

Let's see some BGP prefix received in VRF dn42 bgp table:

so my screen is too small for all the IPv6 BGP prefix into DN42 VRF

As a last example, something we usually do as network operators is to check ongoing interface traffic level:

Code Block

language	bash
theme	Midnight
title	Check interface traffic level (received/transmitted) )

r1#sh int sdn1                                                            
sdn1 is up (since 09:41:21, 2 changes)
 description: mjolnir@LAN1[01:00.0]
 type is sdn, hwaddr=003b.7671.764f, mtu=1500, bw=8000kbps, vrf=inet
 ip4 address=192.168.0.90/24, netmask=255.255.255.0, ifcid=10013
 ip6 address=2a01:e0a:159:2850::666/64, netmask=ffff:ffff:ffff:ffff::, ifcid=10013
 received 52013 packets (17638316 bytes) dropped 5 packets (448 bytes)
 transmitted 80765 packets (15101696 bytes) promisc=false macsec=false

r1#sh int sdn1                                                            
sdn1 is up (since 09:41:22, 2 changes)
 description: mjolnir@LAN1[01:00.0]
 type is sdn, hwaddr=003b.7671.764f, mtu=1500, bw=8000kbps, vrf=inet
 ip4 address=192.168.0.90/24, netmask=255.255.255.0, ifcid=10013
 ip6 address=2a01:e0a:159:2850::666/64, netmask=ffff:ffff:ffff:ffff::, ifcid=10013
 received 52013 packets (17638316 bytes) dropped 5 packets (448 bytes)
 transmitted 80766 packets (15101778 bytes) promisc=false macsec=false

r1#sh int sdn1                                                            
sdn1 is up (since 09:41:24, 2 changes)
 description: mjolnir@LAN1[01:00.0]
 type is sdn, hwaddr=003b.7671.764f, mtu=1500, bw=8000kbps, vrf=inet
 ip4 address=192.168.0.90/24, netmask=255.255.255.0, ifcid=10013
 ip6 address=2a01:e0a:159:2850::666/64, netmask=ffff:ffff:ffff:ffff::, ifcid=10013
 received 52015 packets (17638418 bytes) dropped 5 packets (448 bytes)
 transmitted 80766 packets (15101778 bytes) promisc=false macsec=false

In the last example we repeatedly issue the "sh int sdn1" command and try to see if TX/RX packets counters increment or not.

This command can be improved in order to be less chatty:

Code Block

language	bash
theme	Midnight
title	Check interface traffic level (received/transmitted) )

r1#sh int sdn1 | i received|transmitted                            
 received 52256 packets (17681204 bytes) dropped 5 packets (448 bytes)
 transmitted 81130 packets (15162642 bytes) promisc=false macsec=false

r1#sh int sdn1 | i received|transmitted                            
 received 52256 packets (17681204 bytes) dropped 5 packets (448 bytes)
 transmitted 81130 packets (15162642 bytes) promisc=false macsec=false

r1#sh int sdn1 | i received|transmitted                            
 received 52260 packets (17681496 bytes) dropped 5 packets (448 bytes)
 transmitted 81132 packets (15162790 bytes) promisc=false macsec=false

Same goes if want want interface traffic for all interface

Code Block

language	bash
theme	Midnight
title	Check interface traffic level (received/transmitted) )

show interfaces summary                                                
interface   state  tx        rx        drop
loopback0   up     65856     0         0
loopback42  up     65856     0         0
ethernet0   up     31071917  33183183  0
hairpin41   up     85806     85552     0
hairpin42   up     85806     85552     0
sdn1        up     15200591  17703953  448
sdn2        up     15563546  8000994   794
sdn3        admin  0         0         0
sdn4        admin  0         0         0
sdn5        admin  0         0         0
sdn6        admin  0         0         0
sdn998      up     5850      0         0
sdn999      up     23268     18666     0
tunnel1965  up     5222281   7124950   0

Above was to check interface status related to software switched packet. What if I want to check hardware switched packet counters switched by P4 or DPDK ?

Code Block

language	bash
theme	Midnight
title	Check interface traffic level (received/transmitted) )

show interfaces hwsummary                                              
interface   state  tx         rx         drop
hairpin41   up     0          0          0
hairpin42   up     0          0          0
sdn1        up     317902736  590402538  1162971
sdn2        up     574923844  310497399  203
sdn3        admin  0          0          0
sdn4        admin  0          0          0
sdn5        admin  0          0          0
sdn6        admin  0          0          0
sdn998      up     9062       0          0
sdn999      up     103804     64470      0
tunnel1965  up     0          1301312    0

Tip

title	Note

As a network operator, the "show" command is your best friend, your wingman. Just explore now from freeRouter CLI using "show ?" and you'll understand the amazing list of diagnosis command available.

Expand

title	view

In my previous examples, the output of "show ipv4 bgp 42 unicast database" command could not fit my window. Say hello to "view" keyword then !

Let's now try to get hardware counters as above:

Code Block

language	bash
theme	Midnight
title	Check hardware traffic counters

r1#view ipv4 bgp 42 unicast database
...

Then you'll be able to see READ-ONLY text buffer where you can navigate and check the output that are beyond boundaries of your screen !

Image Added

Tip

title	Note

"view" is similar to "show" but it will let you deal with a fixed buffer. "view" buffer won't be refreshed.

Expand

title	watch

As mentioned above, "show" gives you diagnosis instant photo of a control plane object. In order to see counter increment, you'd have to issue "show" repeatedly. In order to avoid that, let me introduce you the "watch" command

Let's now try to get hardware counters as above:

Code Block

language	bash
theme	Midnight
title	Check hardware traffic counters

r1#watch interfaces hwsummary
...

It will clear the terminal session and gives you the same outout as above but with counter updated in a regular basis

So in this example you'll see a live output with counter incrementing. In the screenshot it is not noticeable, but in real life this is bluffing. See watch interface pretty much like Junos "monitor" keyword.

So needless to say that "watch" is applicable to every control plane object such as BGP:

Amazing, don't you think ?

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Expand

title	display

In my previous examples, the output of "show ipv4 bgp 42 unicast database" command could not fit my window. Say hello to "display" keyword then !

Code Block

language	bash
theme	Midnight
title	Display BGP prefix from dn42 VRF

r1#display ipv4 bgp 42 unicast database
...

Then you'll be able to see READ-ONLY text buffer where you can navigate and check the output that are beyond boundaries of your screen !

As a side note, you can benefit from online help by pressing <f1>

You can press Ctrl+q in order to exit the editor. As the viewer is a READ-ONLY buffer

Tip

title	Note

Use "display" for output that have output that does not fit into your screen. "display" shows a buffer that is auto-refreshed similar to "watch". But instead the output is thrown into a buffer where you can navigate. But display, very useful to diagnoses object such as huge:

ACL
prefix-list
route policy list
route-map

As opposed to "view", "display" proposes an auto-refresh version of the buffer !

Expand

title	differ

Last but not list. "differ" , this will split the window in 2 buffers reflecting the same output but with different version and it it signal line lines that have changed.

Code Block

language	bash
theme	Midnight
title	Check BGP best path computation for BGP process 42

r1#diff ipv4 bgp 42 bestpath
...

With this view you can easily spot the differences between 2 advertisements interval.

To be honest, when i used this feature for the first time I was totally stumbled and said: Waouw ...

Simply amazing ...

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