Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

Bronze

%PLATFORM_UCAST-6-PREFIX

After upgrading to 12.2(44)SE on a C3750 switch, we started getting the following new messages in the system log:

%PLATFORM_UCAST-6-PREFIX: One or more, more specific prefixes could not be programmed into TCAM and are being covered by a less specific prefix.

This is a warning only and this situation was already present before the upgrade (however, the message logging didn't exist). Now our log is full of these messages.

Can we supresses the messages ? And is it safe to do so ?

regards,

Geert

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Silver

Re: %PLATFORM_UCAST-6-PREFIX

Hello Geert,

how many IP prefixes are in the routing table ?

It may be wise to reduce the number of IP prefixes learned by the device they are too many for the TCAM table size.

Or you may think to use the sdm prefer command to change the way the TCAM is used: another template may provide more space for IP prefixes (a reload is needed to be effective)

These two actions should stop these messages.

Hope to help

Giuseppe

4 REPLIES
Hall of Fame Super Silver

Re: %PLATFORM_UCAST-6-PREFIX

Hello Geert,

how many IP prefixes are in the routing table ?

It may be wise to reduce the number of IP prefixes learned by the device they are too many for the TCAM table size.

Or you may think to use the sdm prefer command to change the way the TCAM is used: another template may provide more space for IP prefixes (a reload is needed to be effective)

These two actions should stop these messages.

Hope to help

Giuseppe

Bronze

Re: %PLATFORM_UCAST-6-PREFIX

Thx. I am already waiting for a change window to change the sdm template to routing.

I have done the calculations and we -might- be a bit above the limit. We run the sdm default template:

number of IPv4 unicast routes: 8K

number of directly-connected IPv4 hosts: 6K

number of indirect IPv4 routes: 2K

* What is the difference between 6K and 2K (indirect IPv4 route vs directly-connected IPv4 host) ??

We have +2000 ip routes:

IP routing table name is Default-IP-Routing-Table(0)

IP routing table maximum-paths is 32

Route Source Networks Subnets Overhead Memory (bytes)

connected 0 4 324 608

static 0 1 64 152

ospf 1000 250 2170 285312 367840

Intra-area: 116 Inter-area: 36 External-1: 31 External-2: 2237

NSSA External-1: 0 NSSA External-2: 0

internal 249 291828

Total 499 2175 285700 660428

* I could also summarize our External-2 routes, however, they are non-contigious and i don't want to over-summarize.

* The switch has only 3 OSPF neighbors, so not that many different adjacencies.

* What would be the consequences of running with +200 or +300 routes not in TCAM ? higher CPU ? dropped packets ? I feel the switch is just surpressing some specific prefixes (like /32) that are covered by a more general prefix (ie /24) which is a fine solution (i can live with that, no ?)

Hall of Fame Super Silver

Re: %PLATFORM_UCAST-6-PREFIX

Hello Geert,

>> Intra-area: 116 Inter-area: 36 External-1: 31 External-2: 2237

I would also consider to move the C3750 in a stubby area, this would deplete the OSPF database from so many external routes.

If you feel that this would cause non optimal routing, you can move to the routing SDM template that should provide more space for routes.

>> What is the difference between 6K and 2K (indirect IPv4 route vs directly-connected IPv4 host) ??

the 6K directly connected ipv4 hosts looks like to be the ARP table size.

the 2K indirect routes it is what we would call the routing table size.

>> What would be the consequences of running with +200 or +300 routes not in TCAM ? higher CPU ?

probably an higher cpu but if in the future the number of routes increases the device can be obliged to make difficult choices.

Hope to help

Giuseppe

Bronze

Re: %PLATFORM_UCAST-6-PREFIX

Hello Guiseppe,

The C3750 is part of the backbone network and needs to transmit all backbone routes to remote wan sites...so i can't really change it to stubby area (remote sites needs all routes, not just the default for remote wan failover, complicated setup i know).

However, i have rebooted the switch into sdm routed template and all is well: no TCAM exhaustion and "show platform ip route failed routes" doesn't show anything anymore.

sh sdm prefer now shows 8K of indirect Ipv4 routes:

number of IPv4 unicast routes: 11K

number of directly-connected IPv4 hosts: 3K

number of indirect IPv4 routes: 8K

sh platform ip unicast counts

# of HL3U fibs 2452

# of HL3U adjs 3

# of HL3U mpaths 1

# of HL3U covering-fibs 0

# of HL3U fibs with adj failures 0

Fibs of Prefix length 0, with TCAM fails: 0

Fibs of Prefix length 1, with TCAM fails: 0

Fibs of Prefix length 2, with TCAM fails: 0

Fibs of Prefix length 3, with TCAM fails: 0

Fibs of Prefix length 4, with TCAM fails: 0

Fibs of Prefix length 5, with TCAM fails: 0

Fibs of Prefix length 6, with TCAM fails: 0

Fibs of Prefix length 7, with TCAM fails: 0

Fibs of Prefix length 8, with TCAM fails: 0

Fibs of Prefix length 24, with TCAM fails: 0

Fibs of Prefix length 25, with TCAM fails: 0

Fibs of Prefix length 26, with TCAM fails: 0

Fibs of Prefix length 27, with TCAM fails: 0

Fibs of Prefix length 28, with TCAM fails: 0

Fibs of Prefix length 29, with TCAM fails: 0

Fibs of Prefix length 30, with TCAM fails: 0

Fibs of Prefix length 31, with TCAM fails: 0

Fibs of Prefix length 32, with TCAM fails: 0

Fibs of Prefix length 33, with TCAM fails: 0

Thanks.

Still i wonder what the effect is, we still have +3 other C3750 that have been running fine for months/years with the older software (no notifications) but heavily dropping TCAM entries:

(an old one:)

sh platform ip unicast counts

# of HL3U fibs 2438

# of HL3U adjs 3

# of HL3U mpaths 1

# of HL3U covering-fibs 34

# of HL3U fibs with adj failures 35

Fibs of Prefix length 0, with TCAM fails: 0

Fibs of Prefix length 1, with TCAM fails: 0

Fibs of Prefix length 2, with TCAM fails: 0

Fibs of Prefix length 3, with TCAM fails: 0

Fibs of Prefix length 4, with TCAM fails: 0

Fibs of Prefix length 5, with TCAM fails: 0

Fibs of Prefix length 6, with TCAM fails: 0

Fibs of Prefix length 7, with TCAM fails: 0

Fibs of Prefix length 8, with TCAM fails: 3

Fibs of Prefix length 9, with TCAM fails: 0

Fibs of Prefix length 10, with TCAM fails: 0

Fibs of Prefix length 11, with TCAM fails: 0

Fibs of Prefix length 12, with TCAM fails: 0

Fibs of Prefix length 13, with TCAM fails: 0

Fibs of Prefix length 14, with TCAM fails: 0

Fibs of Prefix length 15, with TCAM fails: 0

Fibs of Prefix length 16, with TCAM fails: 1

Fibs of Prefix length 17, with TCAM fails: 0

Fibs of Prefix length 18, with TCAM fails: 32

Fibs of Prefix length 19, with TCAM fails: 153

Fibs of Prefix length 20, with TCAM fails: 0

Fibs of Prefix length 21, with TCAM fails: 0

Fibs of Prefix length 22, with TCAM fails: 209

Fibs of Prefix length 23, with TCAM fails: 0

Fibs of Prefix length 24, with TCAM fails: 1187

Fibs of Prefix length 25, with TCAM fails: 648

Fibs of Prefix length 26, with TCAM fails: 100

Fibs of Prefix length 27, with TCAM fails: 84

Fibs of Prefix length 28, with TCAM fails: 23

Fibs of Prefix length 29, with TCAM fails: 81

Fibs of Prefix length 30, with TCAM fails: 283

Fibs of Prefix length 31, with TCAM fails: 10

Fibs of Prefix length 32, with TCAM fails: 86

Fibs of Prefix length 33, with TCAM fails: 0

1106
Views
0
Helpful
4
Replies