Leaf Smart System Upgrade (Leaf SSU)
The Smart System Upgrade (SSU) process includes the core functionality of Accelerated Software Upgrade, plus additional optimizations that permit a hitless restart of several features. SSU leverages protocols capable of graceful restart to minimize traffic loss during upgrade. For protocols not capable of graceful restart, SSU generates control plane messages and buffers them in hardware to be slowly released when the control plane is offline. Additionally, under SSU, the forwarding ASIC does not get reset and ports do not flap.
Features capable of hitless restart under SSU include:
- 802.3ad Link Aggregation/LACP
- 802.3x flow control
- BGP (BGP graceful restart must be enabled: see Configuring BGP)
- MP-BGP (BGP graceful restart must be enabled: see Configuring BGP)
- 128-way Equal Cost Multipath Routing (ECMP)
- route maps
- L2 MTU
Upgrading the EOS image with Smart System Upgrade
Using SSU to upgrade the active EOS image is a five-step process:
- Prepare switch for upgrade ( Prepare the Switch for SSU).
- Transfer image file to the switch (Transfer the Image File for SSU). (Not required if desired file is on the switch).
- Modify boot-config file to point to the desired image file (Modify boot-config).
- Start the SSU process (Start the SSU Process).
- Verify that the upgrade was successful (Verify Success of the Upgrade).
Prepare the Switch for SSU
Backing Up Critical Software
Before upgrading the EOS image, ensure thatcopies of the currently running EOS version and the running-config file are available in case of corruption during the upgrade process. To copy the running-config file, use the copy running-config command. In this example, running-config is copied to a file in the flash drive on the switch.
switch#copy running-config flash:/cfg_06162014 Copy completed successfully. switch#
Making Room on the Flash Drive
Determine the size of the new EOS image. Then verify that there is enough space available on the flash drive for two copies of this image, plus a recommended 240MB (if available) for diagnostic information in case of a fatal error. Use the dir command to check the “bytes free” figure.
switch#dir flash: Directory of flash:/ -rwx 293168526Nov 422:17 EOS4.11.0.swi -rwx36Nov 810:24 boot-config -rwx 37339Jun 16 14:18 cfg_06162014 606638080 bytes total (602841088 bytes free)
Ensure that the switch has a management interface configured with an IP addresses and default gateway. Refer the sections, Assigning a Virtual IP Address to Access the Active Ethernet Management Port and Configuring a Default Route to the Gateway (see Assigning a Virtual IP Address to Access the Active Ethernet Management Port and Configuring a Default Route to the Gateway), and confirm that it can be reached through the network by using the command and pinging the default gateway.
switch#show interfaces status PortName Status Vlan Duplex SpeedType Et3/1notconnect 1 autoauto 1000BASE-T <-------OUTPUT OMITTED FROM EXAMPLE--------> Ma1/1connected routed unconf unconfUnknown switch#ping 22.214.171.124 PING 172.22.26.1 (172.22.26.1) 72(100) bytes of data. 80 bytes from 126.96.36.199: icmp_seq=1 ttl=64 time=0.180 ms 80 bytes from 188.8.131.52: icmp_seq=2 ttl=64 time=0.076 ms 80 bytes from 184.108.40.206: icmp_seq=3 ttl=64 time=0.084 ms 80 bytes from 220.127.116.11: icmp_seq=4 ttl=64 time=0.073 ms 80 bytes from 18.104.22.168: icmp_seq=5 ttl=64 time=0.071 ms
Verify that the switch configuration is valid for SSU by using the show reload hitless command. If parts of the configuration are blocking execution of SSU, an error message will be displayed explaining what they are. For SSU to proceed, the configuration conflicts must be corrected before issuing the reload hitless command.
switch#show reload hitless switch#'reload hitless' cannot proceed due to the following: Spanning-tree portfast is not enabled for one or more ports Spanning-tree BPDU guard is not enabled for one or more ports switch#
For hitless restart of BGP and MP-BGP, BGP graceful restart must first be enabled using the graceful-restart command. The default restart time value (300 seconds) is appropriate for mostconfigurations.
The BGP configuration mode in which the graceful-restart command is issued determines which BGP connections will restart gracefully.
- For all BGP connections, use the graceful-restart
command in BGP configuration
switch#config switch(config)#router bgp 64496 switch(config-router-bgp)#graceful-restart switch(config-router-bgp)#
- For all BGP connections in a specific VRF, use the
graceful-restart command in BGP VRF
switch#config switch(config)#router bgp 64496 switch(config-router-bgp)#vrf purple switch(config-router-bgp-vrf-purple)#graceful-restart switch(config-router-bgp-vrf-purple)#exit switch(config-router-bgp)#
- For all BGP connections in a specific BGP address family, use the
graceful-restartcommand in BGP address-family
switch#config switch(config)#router bgp 64496 switch(config-router-bgp)#address-family ipv6 switch(config-router-bgp-af)#graceful-restart switch(config-router-bgp-af)#exit switch(config-router-bgp)#
BGP graceful restart can also be configured for a specific interface.
Transfer the Image File for SSU
The target image must be copied to the file system on the switch, typically onto the flash drive. After verifying that there is space for two copies of the image plus an optional 240MB for diagnostic information, use the copy command to copy the image to the flash drive, then confirm that the new image file has been correctly transferred.
These command examples transfer an image file to the flash drive from various locations.
copy usb1:/sourcefile flash:/destfile
Sch#copy usb1:/EOS-4.14.4.swi flash:/EOS-4.14.4.swi
copy ftp:/ftp-source/sourcefile flash:/destfile
sch#copy ftp:/user:email@example.com/EOS-4.14.4.swi flash:/EOS-4.14.4.swi
copy scp://scp-source/sourcefile flash:/destfile
sch#copy scp://firstname.lastname@example.org/user/EOS-4.13.2.swi flash:/EOS-4.13.2.swi
copy http://http-source/sourcefile flash:/destfile
sch#copy http://10.0.0.10/EOS-4.14.4.swi flash:/EOS-4.14.4.swi
Once the file has been transferred, verify that it is present in the directory, then confirm the MD5 checksum using the verify command. The MD5 checksum is available from the EOS download page of the Arista website.
switch#dir flash: Directory of flash:/ -rwx 293168526 Nov 4 22:17 EOS4.14.2.swi -rwx36 Nov 8 10:24 boot-config -rwx 37339 Jun 1614:18 cfg_06162014 -rwx 394559902 May 3002:57 EOS4.13.1.swi 606638080 bytes total (208281186 bytes free) switch#53#verify /md5 flash:EOS-4.14.4.swi verify /md5 (flash:EOS-4.14.4.swi) =c277a965d0ed48534de6647b12a86991
After transferring and confirming the desired image file, use the boot system command to update the boot-config file to point to the new EOS image.
This command changes the boot-config file to point to the image file located in flash memory at EOS-4.14.4.swi.
switch#configure terminal switch(config)#boot system flash:/EOS-4.14.4.swi
Use the show boot-config command to verify that the boot-config file is correct:
switch(config)#show boot-config Software image: flash:/EOS-4.14.4.swi Console speed: (not set) Aboot password (encrypted): $1$ap1QMbmz$DTqsFYeauuMSa7/Qxbi2l1
Save the configuration to the startup-config file with the write command.
Start the SSU Process
After updating the boot-config file, verify that your configuration supports SSU (if you have not already done so) by using the show reload hitless command. If parts of the configuration are blocking execution of SSU, an error message will be displayed explaining what they are.
switch#show reload hitless switch#'reload hitless' cannot proceed due to the following: Spanning-tree portfast is not enabled for one or more ports Spanning-tree BPDU guard is not enabled for one or more ports
Then start the SSU process using the reload hitless command to reload the switch and activate the new image. The CLI will identify any changes that must be made to the configuration before starting SSU, prompt to save any modifications to the system configuration, and request confirmation before reloading.
switch#reload hitless System configuration has been modified. Save? [yes/no/cancel/diff]:y Copy completed successfully. Proceed with reload? [confirm]y
Verify Success of the Upgrade
Before making any configuration changes to the switch after reload, verify that the SSU process is complete using the command show boot stages log. If the process is complete, the last message should be Asu Hitless boot stages complete.
switch#show boot stages log Timestamp Delta Begin Msg 2015-03-28 15:18:30 000.000000 Asu Hitless boot stages started 2015-03-28 15:18:30 000.069732 stage CriticalAgent started 2015-03-28 15:18:30 000.069811 event CriticalAgent:SuperServer completed 2015-03-28 15:20:20 110.224504 stage BootSanityCheck is complete 2015-03-28 15:20:20 110.225439 Asu Hitless boot stages complete switch#
Completion of the SSU process may also be verified by checking the syslog for the following message:
LAUNCHER-6-BOOT_STATUS: 'reload hitless' reconciliation complete
To verify whether the SSU upgrade was successful, use the show reload cause command. If a fatal error occurred during the upgrade process, the switch will have completely rebooted and the fatal error will be displayed along with the directory in which diagnostic information can be found. If the SSU upgrade succeeded, it will read Hitless reload requested by the user.
Fatal Error Display
switch#show reload cause Reload Cause 1: ------------------- Reload requested by the user. Reload Time: ------------ Reload occurred at Sat Feb 28 02:34:26 2015 PST. Recommended Action: ------------------- No action necessary. Debugging Information: ---------------------- None available. Reload Cause 2: ------------------- Fatal error during 'reload hitless'. (stageMgr - LinkStatusUpdate timed out) Reload Time: ------------ Reload occurred at Sat Feb 28 02:33:54 2015 PST. Recommended Action: ------------------- A fatal error occurred during hitless reload. If the problem persists, contact your customer support representative. Debugging Information: ---------------------- /mnt/flash/persist/fatalError-2015-02-28_023355 switch#
Successful Upgrade Display
switch#show reload cause Reload Cause 1: ------------------- Hitless reload requested by the user. Reload Time: ------------ Reload occurred at Wed Mar 25 14:49:04 2015 PDT. Recommended Action: ------------------- No action necessary. Debugging Information: ---------------------- None available. switch#
The show version command will confirm whether the correct image is loaded. The Software image version line displays the version of the active image file.
switch#show version Arista DCS-7050QX-32-F Hardware version:02.00 Serial number: JPE14071098 System MAC address:001c.7355.556f Software image version: 4.14.5F-2353054.EOS4145F Architecture: i386 Internal build version: 4.14.5F-2353054.EOS4145F Internal build ID:e8748ea7-916d-4217-878f-4bfe2adc7122 Uptime: 4 minutes Total memory: 3981328 kB Free memory:1342408 kB switch#