08-27-2010 09:30 AM - edited 03-04-2019 09:34 AM
So we are looking at upgrading one of our 7206VXR NPE-G1s to 12.2(33)SRD4 from 12.2(31)SB17. We duplicated the production router in the lab running the SB(17) code. Then we upgraded to the SRD4 code and compared the configs. It seems the no auto-summary command has been removed from all of the address-family ipv4 vrfs. I should point out that the default behavior is not to summarize and it isn't summarizing, but the option to enable it isn't there either. I can't see any time when we would want to turn it on but I can't find any documentation saying when that command was removed or changed and it bothers me. I'm still looking but thought I would throw this out there in case someone had a quick reference. There are a lot of release notes to read.
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08-30-2010 09:21 AM
The behavior has been changed in the current IOS.
"The MPLS VPN Per VRF Label feature does not support auto-summary."
http://www.cisco.com/en/US/docs/ios/iproute_bgp/command/reference/irg_bgp1.html#wp1088373
The behavior was modified under vrf address-families because, unlike aggregate-address command, auto-summarization does not install a summary route on the router where summarization is performed. This may lead to scenarios where mpls label switched paths can break. So the cli has been modified to prevent auto-summary configuration under vrf address-families and default behavior is 'no auto-summary' for vrf address-families.
The workaround is to use aggregate-address for BGP summerization under vrf address-families.
HTH,
jerry
08-27-2010 10:11 AM
Hello David,
the default setting is now no auto-summary so it is not shown in configuration
also no sync is now default
Hope to help
Giuseppe
08-27-2010 11:12 AM
Thank you Giuseppe. Are you aware of why they would remove the ability to turn it on vrf by vrf? I do see that no auto-summary is the default and thus the command is removed, but it does not appear that you have the option to enable it in a vrf at all. Note the difference in available commands below.
Thanks
SB17
Router Address Family configuration commands:
aggregate-address Configure BGP aggregate entries
auto-summary Enable automatic network number summarization
bgp BGP specific commands
default Set a command to its defaults
default-information Control distribution of default information
default-metric Set metric of redistributed routes
distance Define an administrative distance
distribute-list Filter networks in routing updates
exit-address-family Exit from Address Family configuration mode
help Description of the interactive help system
maximum-paths Forward packets over multiple paths
neighbor Specify a neighbor router
network Specify a network to announce via BGP
no Negate a command or set its defaults
redistribute Redistribute information from another routing protocol
synchronization Perform IGP synchronization
table-map Map external entry attributes into routing table
timers Adjust routing timers
SRD4
Router Address Family configuration commands:
aggregate-address Configure BGP aggregate entries
bgp BGP specific commands
default Set a command to its defaults
default-information Control distribution of default information
default-metric Set metric of redistributed routes
distance Define an administrative distance
distribute-list Filter networks in routing updates
exit-address-family Exit from Address Family configuration mode
help Description of the interactive help system
maximum-paths Forward packets over multiple paths
neighbor Specify a neighbor router
network Specify a network to announce via BGP
no Negate a command or set its defaults
redistribute Redistribute information from another routing protocol
synchronization Perform IGP synchronization
table-map Map external entry attributes into routing table
08-28-2010 12:33 AM
David,
Just a quick thought: the command may not be visible in the help but if you typed it exactly in the full form, i.e., auto-summary - would it be accepted or not?
Best regards,
Peter
08-30-2010 08:56 AM
I did try that too. Although it does take the command it doesn't seem to do anything. As you can see in the example. Nothing changed in the config. There isn't any auto summarization taking place within the vrf either. It's really not a deal breaker, I would just like an explanation as to why this was removed. The only place I can enable auto-summary is in the ipv4 address family but it only affects the global table not the vrfs.
TESTROUTER(config)#router bgp 65001
TESTROUTER(config-router)#address-family ipv4 vrf test
TESTROUTER(config-router-af)#auto-summary
TESTROUTER(config-router-af)#end
router bgp 65001
!
address-family ipv4 vrf test
no synchronization
bgp redistribute-internal
redistribute connected route-map CUSTOMER-Connected-Redistribute
redistribute static route-map CUSTOMER-Static-Redistribute
neighbor 172.16.1.2 remote-as 65002
neighbor 172.16.1.2 activate
default-information originate
exit-address-family
08-30-2010 09:21 AM
The behavior has been changed in the current IOS.
"The MPLS VPN Per VRF Label feature does not support auto-summary."
http://www.cisco.com/en/US/docs/ios/iproute_bgp/command/reference/irg_bgp1.html#wp1088373
The behavior was modified under vrf address-families because, unlike aggregate-address command, auto-summarization does not install a summary route on the router where summarization is performed. This may lead to scenarios where mpls label switched paths can break. So the cli has been modified to prevent auto-summary configuration under vrf address-families and default behavior is 'no auto-summary' for vrf address-families.
The workaround is to use aggregate-address for BGP summerization under vrf address-families.
HTH,
jerry
08-30-2010 09:26 AM
Excellent!! That is exactly what I was after. Thank you!
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