I have a 2509 with 2 serial interfaces (s0, s1) and 1 ethernet interface (e0). What are subinterfaces? Why do I need them? How do I determine how many subinterfaces I have on a particular interface (ie. s0)? Can I add additional subinterfaces or remove them? ~Faith~
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What are subinterfaces?
- Thread starter FaithH
- Start date
subinterfaces are a way to logically divide a physical port up into more then one interface. You use them on serial and ethernet. On serial one of the most common uses is point to point frame connections. You have one corp router... it's one serial interface may have 10 subinterfaces... one for each remote site. On ethernet subinterfaces are used with VLANs and trunking. On the trunk link, each VLAN will get it's own subinterface and all will be on a single ethernet port.
Adding is simple.. removal to do it right, requires a reboot of the router. IF you dont, weird things can happen.
config t
!
interface serial 0
!
no ip address ; no ip addressing on the port, wait till subinterface
!
interface serial 0.1 ; notice the 0.1, this is subinterface .1 on serial 0
ip address blah-blah-blah
The easy way to see how many is to do a show running or wri t
MikeS
Find me at
"Take advantage of the enemy's unreadiness, make your way by unexpected routes, and attack unguarded spots."
Sun Tzu
Adding is simple.. removal to do it right, requires a reboot of the router. IF you dont, weird things can happen.
config t
!
interface serial 0
!
no ip address ; no ip addressing on the port, wait till subinterface
!
interface serial 0.1 ; notice the 0.1, this is subinterface .1 on serial 0
ip address blah-blah-blah
The easy way to see how many is to do a show running or wri t
MikeS
Find me at
"Take advantage of the enemy's unreadiness, make your way by unexpected routes, and attack unguarded spots."
Sun Tzu
- Thread starter
- #3
wybnormal,
The wr t or sho run only shows my current interfaces like e0, s0, and s1. It doesn't tell me how many subinterfaces I can have for that specific interface. For example, with the s0 interface can I have 5, 10, 15 subinterfaces? Sorry if it's too elementary. I'm still new to routing and switching.
The wr t or sho run only shows my current interfaces like e0, s0, and s1. It doesn't tell me how many subinterfaces I can have for that specific interface. For example, with the s0 interface can I have 5, 10, 15 subinterfaces? Sorry if it's too elementary. I'm still new to routing and switching.
You can have anywhere from a max of 300 to something like 10,000 subinterfaces.. not that it's recommended ;-)
Here is the document for it.
You wont see any subinterfaces until they are configured.
MikeS
Find me at
"Take advantage of the enemy's unreadiness, make your way by unexpected routes, and attack unguarded spots."
Sun Tzu
Here is the document for it.
You wont see any subinterfaces until they are configured.
MikeS
Find me at
"Take advantage of the enemy's unreadiness, make your way by unexpected routes, and attack unguarded spots."
Sun Tzu
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