IBM SC30-3681-08 manual Conguring Multi-Chassis MP, Hunt group

Using MP

Config> feature layer-2-tunneling
Layer-2-Tunneling Config> encapsulator
PPP-L2TP Config> enable mp
NOTE: It IS necessary to configure PPP for this net!					PPP
	negotiation parameters must be configured the same for
	all nets wishing to join the same Multilink PPP bundle.
PPP-L2TP Config>
Con®guring Multi-Chassis MP
To con®gure MP for Multi-Chassis MP, con®gure the DIALs feature for multi-chassis
MP. The software prompts you for the endpoint discriminator to use.
Example:
Config> feature DIALs
DIALs Config> set multi-chassis-mp
	Enter Endpoint Discriminator to use from stacked group (0 for box S/N): 2345
DIALs Config>
The following example shows multichassis MP when ports RTR-2 and RTR-3 are in
a hunt group.
			221X -access
			RTR-A
		ISDN				221X -access RTR-Z
	Client					MP-concentrator
			221X -access
			RTR-B
				L2TP Tunnels
Figure 29. Multichassis MP
Because there is a many-to-many relationship between access routers and
MP-concentrators, all access routers (RTR-A, RTR-B) should be kept on a separate
administrative domain from ªMP concentratorº routers (RTR-Z). This applies if you
want to use remote authentication (that is,RADIUS), you will need two RADIUS
servers, one for access routers and one for MP concentrators. If you are using
local-list, you are already using separate administrative domains.
In this scenario, you can choose to tunnel based on PPP username or ²rhelm²
name. It is less rigorous to use rhelm-based tunneling. The idea is to con®gure a
tunnel-pro®le for RTR-Z on both RTR-A and RTR-B. No additional PPP users are
required on these routers. RTR-Z would require 2 tunnel-pro®les: one for RTR-A
and one for RTR-B and a PPP username (in the form <username>@RTRZ) for
each anticipated user. All dial-in circuits are con®gured on the ªaccessº routers. The
ªMP concentratorsº would have layer-2-tunneling devices and multilink-PPP devices.
At this point, we have ªstatically con®guredº multi-chassis MP. This means that a
particular PPP username will always terminate MP on a precon®gured router as
opposed to supporting an additional protocol which dynamically ®nds MP bundle
heads and tunnels when needed. This network implementation will also help avoid

Chapter 34. Using the Multilink PPP Protocol 513