12-08-2009 06:27 AM - edited 03-04-2019 06:54 AM
Hi,
We are using VRF-Lite and BGP on a customer router, and trunking to a customer switch internally. We are seeing a very large routing table (in excess of 200k routes).
We are seeing an error message:
TAGCON-3-LCLTAG_ALLOC : Cannot allocate local tag
Which I understand is usually only seen when running MPLS, which we are not.
Even stranger, it is resolved by the 'tag-switching tag-range downstream 16 100000 0' (now deprecated).
I notice that the output of 'show tag-switching forwarding-table ..' shows each route being allocated an internal tag.
Can anyone explain why these tags are being assigned?
Thanks.
12-08-2009 06:33 AM
Hello Ken,
you haven't provided much details.
What model is the customer router and what IOS is running on it?
You may have configured the device as you say for VRF lite but it may be trying to assign an MPLS label or older name tag to each prefix in the routing table
another way to solve this would be to use an ACL to decide for what prefixes a tag has to be allocated
something like
no tag-switching advertise-tags
tag-switching advertise-tags for ACLname
the device thinks it is a full PE node.
Hope to help
Giuseppe
12-08-2009 06:58 AM
Hi Guislar,
for further info:
Cisco 3845
IOS: c3845-spservicesk9-mz_124-19b
ip cef
ip vrf DIA
rd 29000:1
!
interface GigabitEthernet0/0.10
description customer Lan Office
encapsulation dot1Q 10
ip address XXXX XXXX
no cdp enable
!
interface GigabitEthernet0/0.11
description customer LAN internet
encapsulation dot1Q 11
ip vrf forwarding DIA
ip address XXXX XXXXX
no cdp enable
!
interface GigabitEthernet0/1
no ip address
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/1.38
encapsulation dot1Q 38
ip address XXXXXXX mask XXXXXXX
no cdp enable
!
interface GigabitEthernet0/1.40
encapsulation dot1Q 40
ip vrf forwarding DIA
ip address XXXXXX mask XXXXXXXXX
no cdp enable
!
router bgp XXXXX
no synchronization
bgp log-neighbor-changes
network XXXXXXX mask XXXXXX
network XXXXXXX mask XXXXXX
network XXXXXXX mask XXXXXX
neighbor XXXXXX remote-as XXXX
neighborXXXXXX version 4
default-information originate
no auto-summary
!
address-family ipv4 vrf DIA
neighbor XXXX remote-as XXXX
neighbor XXXX version 4
neighbor XXXX activate
no synchronization
exit-address-family
!
The 'safe' parts of the config.
Okay, its not a real fault, more interested in why the internal tags are being assigned in the first place.
Does anyone have any ideas?
12-08-2009 10:14 AM
Hello Ken,
the explanation can be as simple as a default settings.
it is enough that mpls ip/tag-switching ip is enabled by default in global mode to lead the device to start allocating labels.
IOS: c3845-spservicesk9-mz_124-19bip cef
if so you just need
conf t
no mpls ip
or
no tag-switching ip
to free resources.
see
Label switching of IPv4 packets along normally routed paths is enabled for the platform.
http://www.cisco.com/en/US/docs/ios/mpls/command/reference/mp_m1.html#wp1013428
Hope to help
Giuseppe
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