Cisco 7609 RSP720-3CXL-GE "mls cef maximum-routes"

[jkwakman]

We receive syslog warnings that we run  to the threshold for the maximum supported mpls routes in the CEF table, below some information.

What is the impact/risc if the threshold is exceeded?

What is the service impact when increasing the settings?

What do we do with the redundant sup720?

is there some good documentation on this? in particular the RSP720-3CXL-GE (I found some old stuff on CATOS and sup32)

ASDGTS1CRT01#sh mls cef maximum-routes
FIB TCAM maximum routes :
=======================
Current :-
-------
IPv4                - 450k
MPLS                - 384k
IPv6 + IP Multicast - 88k (default)

ASDGTS1CRT01#sh mls cef sum

Total routes:                     750214
    IPv4 unicast routes:          375897
    IPv4 Multicast routes:        3
    MPLS routes:                  374036
    IPv6 unicast routes:          0
    IPv6 multicast routes:        0
    EoM routes:                   278

[nkarpysh · Accepted solution]

Hello,

Actually RSP720-3CXL can get up to 1M of IPv4 +MPLS routes. Your current values are 450k+384K=834K. So you have some room to increase that:

- Theoretically this maximum number of routes can be adjusted by the following commands:

mls cef maximum-routes ip  500

mls cef maximum-routes mpls 500  

reload

500 or any number that can support all the routes.

- Please be aware that if we change the maximum number of IPv4 + MPLS routes to 1M, there will be little resource for IPv6 and Multicast.

IPv4                - 500k

MPLS                - 500k

IPv6 + IP Multicast - 8k (default)

- Also changing that you can exaust all available memory in TCAM. In some cases that can lead to CEF auto switch off to resume the normal operation of router. In turn this can lead for packets to be processed switched. So fine tuning should be done accurately.

Answering to your questions:

What is the impact/risc if the threshold is exceeded?

- If total is below the Processor limit - then CEF just stop storing routes above limit to TCAM - and those can be software switched increasing CPU load.  If it will be close to physical limit - then memory can be exausted and in some corner cases CEF can be auto switched off to resume normal operation of router.

What is the service impact when increasing the settings?

- you need to reload to apply changes, also reaching the maximum limits can sometime lead to CEF problems due to no memory

What do we do with the redundant sup720?

- Redundant SUP does not participate in control plane decisions - it just synch it's state with active one. Nothing more

is there some good documentation on this?

I used this one:

http://www.cisco.com/en/US/prod/collateral/routers/ps368/product_data_sheet0900aecd8057f3b6.html

http://www.cisco.com/en/US/docs/routers/7600/ios/12.2SR/configuration/guide/rsp720.html#wp1096004

http://www.cisco.com/en/US/partner/docs/ios/ipswitch/command/reference/isw_i1.html#wp1087660

Hope this helps,

Nik

[jkwakman]

Is a reload of the entire box needed? do all line cards need a reboot also?

or is it possible that we first do a reboot of the redundant supervisor and after that a switchover so it becomes active and next do reboot of the other supervisor?

[nkarpysh · Accepted solution]

Whole reload needed as this should be populated to TCAM.

If you just reload standby - it would still get in synch with active and get current TCAM values from it thus your changes will not be applied. Thus Maintenance Window should be organized for that. But I would also start checking the routes - if there is any possibility to remove some. You don't have too much room for TCAM increase so might soon get it filled as well and then you ill reach HW limit. So possibly a good chance to start revising those now.

Though that is really depends on your NW.

Hope this helps.

Nik

[jkwakman]

Thanks for the answers

[Dani Simanjuntak]

can you recommend me what supervisor engine would i use if i would upgrade my supervisor  sup32 ?

[nkarpysh]

Hello Dani,

Not sure what you mean by compatibility matrix. To learn more about different supervisors you go through the following article:

http://www.cisco.com/c/en/us/td/docs/routers/7600/Hardware/Hardware_Guides/Supervisor_Engine_and_Route_Switch_Processor_Guide/76-sup-rsp.pdf

Niko