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How many vty lines?

On a typical router, there are 5 vty lines vty 0 4, but you can increase that number. However, you cannot delete the origninal 5. (BTW, if you define, say line vty 5 10, then you do no line vty 8, then it deletes line vty 8 and above.)

A Cat 4500 switch behaves in the same way as a router.

On a Cat 2900XL or Cat 2950 switch, there are 16 vty lines defined by default, in two groups, 0-4 and 5-15. These cannot be deleted, and you cannot add to the range.

Can anyone tell me the design rationale behind having so many vty lines on a layer-2 switch? Apart from remote login to management functions, what can they be used for, and is there any reason for the difference in behaviour from a router?

Kevin Dorrell



Re: How many vty lines?


From tinkering in my lab, some routers (e.g. 2500's) won't accept any additional vty lines in their config at all. A 2600 IOS 12.3 will do up to 16 (in two groups, just like the 29xx switches), a 7505 RSP2 IOS 12.4 will do up to 999 (!) in two groups, the second being 5-999. In this last context, 16 doesn't seem like very many [GRIN].

Therefore it seems the maximum is specific to the platform (and/or tied to memory).

As far as I know, they work exactly the same.



Re: How many vty lines?

Multiple management activities from a management platform?

I dunno, good question!

Maybe provide some flexibility for multiple user levels? Five for level 15, five for level 10, five for level 1 ??? One session for each management level?

Maybe to satisfy some feature checklist for RFPs? Another competitor has 10 Telnet sessions, so Cisco put in fifteen ... something like that. IT would help reduce the number of RFPs where the creators target some vendor-specific feature to make sure that only one vendor "fits the bill."

Of all of the explanations, odd as it seems, the "Feature List" explanation rings the truest for me ... "Marketing Makes the World Go Around, doncha know......"

"*WE* have fifteen telnet session s support .... can the OTHER guys say that??????"

Stranger things have happened ....



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