Router config question... hard set all int's?

mikearama

I can't locate a cisco answer to this... hoping you techies can shed some light.

We've contracted an outside vendor to help us roll out our MPLS wan solution. The vendor has asked us to hard set all interfaces to 100/Full.

We are a completely, 100% cisco shop (well, 99%... we use TopLayer IPS's), so our core (4500's) will connect directly to our "MPLS" router (3825), which connects directly to Bell's CE Router (2821). On the branch end, the Bell CE router will again directly connect to our branch MPLS router (1841's), which will connect to Cat3750's.

Since all connections are cisco to cisco, I'd be partial to letting auto/auto handle it all, and had config'd the routers accordingly. The vendor asked me to change them as stated, going so far as to say that "cisco's best practice is to hard set". HUH?

Your thoughts?

dtlokee

The recommendation that you you should set the speed/duplex settings goes back to the days when autonegotiation was optional in the specification for 100Mb/s and you needed to set it. Bottom line is if one side is set the other side needs to be set. Autonegotiation it part of the psec for gigabit interfaces, so if you are using all gigabit interafces I would leave them auto unless the vendor who controls the other side has hsrd coded the speed and duplex.

mikearama

From our core to our MPLS router is a gig link, so auto will stay there. All other int's are fast, not gig.

I guess I dislike the idea that current cisco devices can't autonegotiate properly, and I automatically think this vendor's SE is retarded for living in the past.

So dt... has cisco taken a position that hard setting is still the better option?

dtlokee

I guess the assumption is the routers are not going to be moved so why not set the speed and duplex? It is presented that way in the Cisco courseware. The problem is when you get somone who doesn't understand that BOTH ends need to be hard coded if you set it on one end. I have seen numerous configs where the switch had all the interfaces set to 100 full and the host computers were set to auto.

From a router to a switch there is no reason not to configure both sides, but it is not required. I have not had a problem with leaving autonegotiation on for atleast 10 years. It's been awhile since I have heard an "official" response about this from Cisco, but they teach it in the courses that you should hard set both sides (but then mention nothing of using portfast on your router connections, go figure)

EdTheLad

Ask the outside vendor why they require the interfaces hard reset.If the only reason is Cisco best practices, forget about it.Cisco best practices do not suit every network, in alot of cases Cisco best practices are written in tech manuals by the theoritical engineer and are not even implemented in practice.Its funny the amount of customers that implement something which breaks their network because a book says its best practices.