show ip route on Cisco 1841

[johnlloyd_13]

hi all,

we have a Cisco 1841 router and checked something an unnusual (never seen before) routing table having L - local routes. please advise if this an IOS bug or same as C - connected local routes.

1841#sh ver
Cisco IOS Software, 1841 Software (C1841-IPBASE-M), Version 15.0(1)M3, RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2010 by Cisco Systems, Inc.
Compiled Sun 18-Jul-10 01:16 by prod_rel_team

1841#sh ip ro
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, + - replicated route

Gateway of last resort is 203.120.215.XX to network 0.0.0.0

S*    0.0.0.0/0 [1/0] via 203.120.215.XX
      203.120.202.YY/24 is variably subnetted, 2 subnets, 2 masks
C        203.120.202.YY/27 is directly connected, FastEthernet0/1
L        203.120.202.YY/32 is directly connected, FastEthernet0/1
      203.120.215.XX/24 is variably subnetted, 2 subnets, 2 masks
C        203.120.215.XX/30 is directly connected, FastEthernet0/0
L        203.120.215.XX/32 is directly connected, FastEthernet0/0

1841#sh ip int bri
Interface                  IP-Address      OK? Method Status                Protocol
FastEthernet0/0            203.120.215.XX  YES manual up                    up     
FastEthernet0/1            203.120.202.YY YES manual up                    up

[Atif Awan]

johnlloyd_13 wrote:
hi all,
we have a Cisco 1841 router and checked something an unnusual (never seen before) routing table having L - local routes. please advise if this an IOS bug or same as C - connected local routes.
1841#sh ver
Cisco IOS Software, 1841 Software (C1841-IPBASE-M), Version 15.0(1)M3, RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2010 by Cisco Systems, Inc.
Compiled Sun 18-Jul-10 01:16 by prod_rel_team
1841#sh ip ro
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area 
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, + - replicated route
Gateway of last resort is 203.120.215.XX to network 0.0.0.0
S*    0.0.0.0/0 [1/0] via 203.120.215.XX
      203.120.202.YY/24 is variably subnetted, 2 subnets, 2 masks
C        203.120.202.YY/27 is directly connected, FastEthernet0/1
L        203.120.202.YY/32 is directly connected, FastEthernet0/1
      203.120.215.XX/24 is variably subnetted, 2 subnets, 2 masks
C        203.120.215.XX/30 is directly connected, FastEthernet0/0
L        203.120.215.XX/32 is directly connected, FastEthernet0/0

1841#sh ip int bri
Interface                  IP-Address      OK? Method Status                Protocol
FastEthernet0/0            203.120.215.XX  YES manual up                    up      
FastEthernet0/1            203.120.202.YY YES manual up                    up

This is not a bug. This was introduced with support for MTR (Multi Topology Routing) and should be there in all IOS versions that support MTR.

Atif

[johnlloyd_13]

hi atif,

thanks for your feedback! any links or documentation to support this?

[Atif Awan]

johnlloyd_13 wrote:
hi atif,
thanks for your feedback! any links or documentation to support this?

I know this based on some research I did on this a while back. I do not have any public documentation pointers unfortunately. Please consider opening a TAC case if you need that.

Atif

[johnlloyd_13]

hi atif,

i found some Cisco documentation regarding MTR. but this router isn't running VRF. it is only a stub router connected to a single ISP.

[Atif Awan]

johnlloyd_13 wrote:
hi atif,
i found some Cisco documentation regarding MTR. but this router isn't running VRF. it is only a stub router connected to a single ISP.

Hello John,

MTR and VRFs are not directly related so I am not sure what is your concern. That being said the presence of the L - Local routes are not a point of concern. I was just mentioning that they became visible as part of a code change done to support MTR so whichever IOS version supports MTR, it will have these routes visible in the output of the show ip route command. These were always there in the backend to facilitate the CEF receive entries, the difference is that now they are actually visible. Rest assured this is not a bug.

Atif

[k_srinadh]

Hi John,

Pls go thro following Link for MTR documentation

http://www.cisco.com/en/US/docs/ios/mtr/configuration/guide/12_2sr/mtr_12_2sr_book.pdf

http://www.cisco.com/en/US/docs/ios/mtr/configuration/guide/12_2sr/mtr_12_sr_book.html

Regards,

Srinadh.