passive interface vlan 50

[alsayed]

Hi

i need to know with detail what does it mean this command"passive interface vlan 50"?;description;usefulllink it is very much appreciated.

10xs

ali

[ankurbhasin · Accepted solution]

Hi Ali,

"passive-interface" router configuration command is applied to stop sending routing updates on an interface.

It behaves different for different routing protocol like for EIGRP the passive-interface command disables the transmission and receipt of EIGRP hello packets on an interface so the neighborship will not form on that interface which is configured as passive interface.

In OSPF, hello packets are not sent on an interface that is specified as passive. Hence, the router will not be able to discover any neighbors, and none of the OSPF neighbors will be able to see the router on that network.

But for RIP and IGRP it does not send the routing updates out on that interface which is configured as passive but still that interface will be advertised out from other interfaces.

Have a look at this link for more details

http://www.cisco.com/en/US/products/sw/iosswrel/ps1830/products_feature_guide09186a008008784e.html#wp11573

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr_c/ipcprt2/1cfindep.htm#wp1019396

Now depending upon the routing protocol you have configured interface vlan 50 will not advertise the routes out from the interface vlan 50 and if you have configured eigrp or ospf it will not form any neighborship with peer on interface vlan 50.

HTH, if yes please rate the post.

Ankur

[alsayed]

hi ankur

10xs for ur reply.

ali

[Richard Burts]

Perhaps a slight clarification is in order. When Ankur says:

But for RIP and IGRP it does not send the routing updates out on that interface which is configured as passive but still that interface will be advertised out from other interfaces.

it implies that the passive interface is advertised out from other interfaces only in RIP and IGRP. But the passive interface is also advertised out other interfaces in EIGRP and in OSPF.

HTH

Rick

[devang_etcom]

hi Rick,,,

will u clear me it in detail please

regards

Devang

[Richard Burts]

Devang

I am not clear what you do not understand nor what kind of detail that you need. If my explanation is not clear perhaps you can clarify what it is that you need.

When an interface matches a network statement in a dynamic routing protocol (including IGRP, EIGRP, OSPF, and RIP) the default is to actively send routing updates through that interface (and in the case of EIGRP and OSPF to also send hello messages). If we configure the routing protocol to make an interface passive then the routing updates are not sent out that interface (and EIGRP and OSPF hello are not sent). If EIGRP and OSPF hello are not sent then no neighbor relationship will form on that interface.

For all of these protocols (IGRP, EIGRP, OSPF, and RIP) the subnet found on the passive interface is advertised out the active interfaces.

If there is something else that you need to understand please clarify.

HTH

Rick