Requirement
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Overview
As previously mentioned in the precedent article, when you log into a network equipment such as a router, you tend to have some automatic reflex. You usually:
- Check router configuration: show run or sh conf
- Check ipv4 / ipv6 / or LFIB forwarding table
- So you basically issue diagnosis, troubleshooting command
- An then you want to configure the router
Article objective
In this article, we will focus on the 3rd bullet point and will present you freeRouter available diagnosis command. They are grouped into 5 categories:
- show
- view
- watch
- display
- differ
Basically these commands are accessed through freeRouter user mode. If you need to use them from config mode, please use the "do" keyword.
[ #002 ] - "show/view/watch/display/differ"
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:
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
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
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:
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:
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
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 ?
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
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.
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:
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 !
Note
"view" is similar to "show" but it will let you deal with a fixed buffer. "view" buffer won't be refreshed.
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:
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 ?
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 !
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
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 !
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.
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 ...
Discussion
show/view/watch/display/differ is pretty unique to freeRouter, and is really meant to provide you the best user experience as a network operator ! These command have proven to be helpful, especially if you deal with huge feed. However, be careful when you are working with very big output such BGP full feed. This won't crash the router of course as we used to when we issued "debug ip packet" but it will for sure imply a high CPU usage due to regular refresh at the control plane level.
Conclusion
In this 2nd article:
- We presented freeRouter show/watch/display/differ diagnisis command
- These are very useful when you have to deal with huge command output buffer.
Final words
As said, these are diagnosis commands are specific to freeRouter. 2 decades of know how and network experience have been pushed into these feature codes. These have been developed for one purpose:
"Provide a unique operation experience to network engineers"
Feel free to try and use them according to your environment taste!
Last but not least, you can play with these different mode from this sandbox:
ssh dl.nop.hu -l random_user Warning: Permanently added 'dl.nop.hu,193.224.23.5' (RSA) to the list of known hosts. random_user@dl.nop.hu's password: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXX XXXXX XXX XXX XXX XX XX XXXX XXXXXXXXXXXXXXXXXXX XXXX XXXX XX XXXX XX XXXX XX XX XX XXXX XXXXX/~~~~~~\XXXXXX XXXX X XXX XX XXXX XX XXXX XX XX XX XXXX XXXX| player |XXXXX XXXX XX XX XX XXXX XX XXX XX XXXX XXXXX\______/XXXXXX XXXX XXX X XX XXXX XX XXXXXXX XX XX XXXX XXXXXXXXXXXXXXXXXXX XXXX XXXX XX XXXX XX XXXXXXX XX XX XXXX XXXXXXXXXXXXXXXXXXX XXXX XXXXX XXX XXX XXX XXX XX XXX XXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX welcome line ready menu lab: # - reboot router1 $ - reboot router2 % - reboot router3 1 - connect to router1 2 - connect to router2 3 - connect to router3 ^ - rebuild routers l - connect to lg.nop.dn42 x - exit choose:l - telnet 172.23.199.110 23 /telnet - connecting to 172.23.199.110 23 - securing connection hi there! try the following: show ipv4 route dn42 show ipv6 route dn42 show ipv4 bgp 65535 vpnuni summary show ipv6 bgp 65535 vpnuni summary show ipv4 bgp 65535 vpnuni database show ipv6 bgp 65535 vpnuni database show ipv4 bgp 65535 vpnuni allroute <prefix> 65535:42 show ipv6 bgp 65535 vpnuni allroute <prefix> 65535:42 show ipv4 logger 42 flapstat 10 show ipv6 logger 42 flapstat 10 show ipv4 bgp 65535 vpnuni flapstat 10 show ipv6 bgp 65535 vpnuni flapstat 10 show ipv4 bgp 65535 vpnuni flappath <prefix> 65535:42 show ipv6 bgp 65535 vpnuni flappath <prefix> 65535:42 have fun! mc36 welcome line ready player-dn42> player-dn42> ...
Then issue a "diff" command:
player-dn42>diff ipv4 bgp 65535 vpnuni database 10.11.160.0/20 65535:42 ...
You'll be rewarded by this diff out related to the command which means:
"show me the prefix status of 10.11.160.0/20 within BGP process 65535 with rd: 65535:42"
After a quick look at VRF definition indicates that rd 65535:42 is tied to VRF dn42:
player-dn42>sh start vrf vrf definition dn42 rd 65535:42 rt-import 65535:42 rt-export 65535:42 source4route all source6route all mdt4 mdt6 exit vrf definition rtbh rd 65535:666 rt-import 65535:666 rt-export 65535:666 exit vrf definition vpn rd 65535:1 rt-import 65535:1 rt-export 65535:1 mdt4 mdt6 exit ...
In order to exit the sandbox session use the following escape sequence: Ctrl-c + Ctrl-x
