From: robbie (robbie@packetized.org)
Date: Wed Jun 22 2005 - 20:10:04 GMT-3
(Brians or Scott, please correct me if I am wrong here)
aal5mux is when you're doing PPP or another layer 2 protocol across a
link, IIRC. aal5snap is just pure IP across ATM with SNAP as the
higher-order layer 2 protocol, which is what you should be using for
most point-to-point ATM network links where all of the VC configuration
is handled on the switch.
Example:
This is a point-to-point ATM configuration for a routed (read: non-PPP)
connection to a remote network
#show run int atm 3/0.253
Building configuration...
Current configuration : 238 bytes
!
interface ATM3/0.253 point-to-point
ip address 172.30.255.69 255.255.255.252
no ip mroute-cache
pvc 1/283
protocol ip 172.30.255.70 no broadcast
encapsulation aal5snap
!
end
Notice that we're not using PPP, just pure SNAP across the link. Here's
another config, from a PPPoA link:
#show run int atm 3/0.92
Building configuration...
Current configuration : 152 bytes
!
interface ATM3/0.92 point-to-point
no ip mroute-cache
pvc 1/123
encapsulation aal5mux ppp Virtual-Template2
!
interface Virtual-Template2
bandwidth 768
ip unnumbered Loopback1
no peer default ip address
ppp authentication pap
end
While the above config doesn't really reflect this, you can configure
your PPP options in much the same way you would if you had a dial-up
client hitting this port. HTH
Cheers,
Robbie
ccie2be wrote:
> Hi guys,
>
> I just came across something interesting and a bit scary.
>
> I was configuring ppp over ATM and since I didn't remember exactly every
> command needed, I checked the Doc-CD.
>
> In the doc-cd, all the examples used the aal5mux encap, so that's what I
> did. Surprise, surprise. It didn't work.
>
> After checking the SG and the config of the remote router for this task, I
> saw that aal5snap encap was being used.
>
> Once I reconfigured my router with aal5snap encap, it worked like a charm.
>
> But, this leads me to a couple questions:
>
> 1. If we're not explicitly told which aal5 encap to use in the lab,
> is there a way to figure out which encap to use other than by trial or
> error?
>
> 2. The actual solution was like this:
>
> int atm0.201 p2p
> pvc 0/201
> encap aal5snap
> protocol ppp virtual-template 1
>
>
> I couldn't find any example like this on the Doc-CD. Does such an example
> exist? IF so, where?
>
> 3. Based on my results, I assume the encap type must be the same on
> both sides. Is this true?
>
>
> Any insight on this would be greatly appreciated.
>
> TIA, Tim
>
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