neighbors in exchange state

cisco steps · ‎09-23-2009

I have an issue w/ two site , this is used to work just fine and the connections have been checked on both sides, and port has been changed in location 1.

Circuit continues to bounce, and still takes errors.Interestingly enough neighbor never restores, and currently shows like this below:

Neighbor

IP Interface Router ID IP Address State Type

location one - x.x.x.x x.x.x.x x.x.x.x Exchange Dynamic

location two - x.x.x.x x.x.x.x x.x.x.x Exchange Dynamic

Giuseppe Larosa · ‎09-23-2009

Hello Ocporbust,

the two devices are able to exchange OSPF hellos but they are not able to exchange database packets that are big packets.

if the line has many errors a big packet is likely errored while is enough to have a success rate of 50% on hellos to keep the neighborship in the first states.

you can see this as a confirmation that the link is too much errored.

Hope to help

Giuseppe

Peter Paluch · ‎09-23-2009

Hello,

In addition to Giuseppe's hint, is it also possible that the MTU of your interfaces has somehow changed? The OSPF does not like if two or more peers on a common link have mismatched MTUs. Also a couple of other reasons may cause two OSPF neighbors to remain stuck in Exchange/ExStart state. Have a look at this document for more details:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f0d.shtml

Best regards,

Peter