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VWIC-2MFT-T1-DI Configuration

xephael
Level 1
Level 1

I'm setting up a bonded T1 for internet access and was sent a sample configuration which reads:

controller T1 0/0

framing esf

linecode b8zs

channel-group 0 timeslots 1-24 speed 64

!

controller T1 0/1

framing esf

linecode b8zs

channel-group 0 timeslots 1-24 speed 64

!

interface MFR1

mtu 4470

no ip address

no ip redirects

no ip proxy-arp

encapsulation frame-relay IETF

no ip route-cache cef

no ip mroute-cache

load-interval 30

no arp frame-relay

frame-relay lmi-type ansi

frame-relay multilink bid to gw

!

interface MFR1.500 point-to-point

ip address 157.130.101.42 255.255.255.252

no ip redirects

no ip proxy-arp

no arp frame-relay

no cdp enable

frame-relay interface-dlci 500 IETF

!

interface FastEthernet0/0

ip address 154.160.23.1 255.255.255.252

duplex full

no cdp enable

!

interface Serial0/0:0

mtu 4470

bandwidth 1536

no ip address

no ip redirects

no ip proxy-arp

encapsulation frame-relay MFR1

no arp frame-relay

!

interface Serial0/1:0

mtu 4470

bandwidth 1536

no ip address

no ip redirects

no ip proxy-arp

encapsulation frame-relay MFR1

no arp frame-relay

!

ip classless

ip route 0.0.0.0 0.0.0.0 MFR1.500

no ip http server

ip pim bidir-enable

!

!

no cdp run

!

call rsvp-sync

!

!

mgcp profile default

!

dial-peer cor custom

!

end

In looking at this a few things came to mind that I was hoping an expert could help clear up.

The first thing was, under interface Serial0/0&1:0 do you really need to specify those no commands?

Secondly can the commands under "interface MFR1.500 point-to-point" and "interface MFR1" be merged?

(ie:

interface MFR1.0 point-to-point

mtu 4470

ip address 157.130.101.42 255.255.255.252

no ip redirects

no ip proxy-arp

encapsulation frame-relay IETF

no ip route-cache cef

no ip mroute-cache

no arp frame-relay

no cdp enable

load-interval 30

no arp frame-relay

frame-relay lmi-type ansi

frame-relay multilink bid to gw

frame-relay interface-dlci 500 IETF

)

Just trying to learn a bit more about Cisco configurations and the reasons why things are done the way they are.

1 Accepted Solution

Accepted Solutions

tbaranski
Level 4
Level 4

1) As with any device configuration, some commands are essential to acheive the functionality you desire and some are just desirable. In the above case, IP addresses on the physical serial interfaces aren't necessary because the logical MFR interfaces are the ones "doing the work", if you will. Turning off IP redirects and proxy-arp tends to make good sense from a security standpoint, so that's why those commands are there. Frame Relay ARP is turned off either because it isn't necessary or maybe isn't compatible with MFR. In general, it's a good idea to turn off features that aren't needed, hence MCI including the above commands in their customer router templates.

As for merging commands, you can't do it the way you asked about above. In Ciscoland, an X.Y interface (e.g., MFR1.500) is a logical subinterface of interface X (MFR1). You can search for the term "subinterface" for more info, but basically a subinterface is a separate interface from the router's standpoint, and you can do neat (and common) things like have multiple subinterfaces of a single physical interface, which is a beneficial (and sometimes necessary) way of separating things logically.

In your case, MCI tends to use point-to-point Frame Relay interfaces on their T1s, so that's what's configured in the template. Some commands have to go under the physical interface (they apply to all subinterfaces as well), and some have to go under the subinterface (in which case they apply only to that subinterface).

View solution in original post

2 Replies 2

xephael
Level 1
Level 1

Anyone able to address this question?

tbaranski
Level 4
Level 4

1) As with any device configuration, some commands are essential to acheive the functionality you desire and some are just desirable. In the above case, IP addresses on the physical serial interfaces aren't necessary because the logical MFR interfaces are the ones "doing the work", if you will. Turning off IP redirects and proxy-arp tends to make good sense from a security standpoint, so that's why those commands are there. Frame Relay ARP is turned off either because it isn't necessary or maybe isn't compatible with MFR. In general, it's a good idea to turn off features that aren't needed, hence MCI including the above commands in their customer router templates.

As for merging commands, you can't do it the way you asked about above. In Ciscoland, an X.Y interface (e.g., MFR1.500) is a logical subinterface of interface X (MFR1). You can search for the term "subinterface" for more info, but basically a subinterface is a separate interface from the router's standpoint, and you can do neat (and common) things like have multiple subinterfaces of a single physical interface, which is a beneficial (and sometimes necessary) way of separating things logically.

In your case, MCI tends to use point-to-point Frame Relay interfaces on their T1s, so that's what's configured in the template. Some commands have to go under the physical interface (they apply to all subinterfaces as well), and some have to go under the subinterface (in which case they apply only to that subinterface).

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