Cisco Systems DNC-305 manual Using the Stack Group Bidding Protocol, DNC-319

Telco and ISP Dial Scenarios and Configurations

Large-Scale POPs

Figure 56 A Stack Group of Access Servers Using MMP with an Offload Processor

Dial-in session #1

PC running Windows 95

Stack of three Cisco AS5200 access servers used in one service provider network

			Hunt
			group
			555-1001
		Cisco 766		#1
				1
			3
Dial-in session #2			2	#2
		4
	Terminal		C	A
		ISDN network
PC	adapter
				#3
			D
		Analog network		B

				Remote security
				server
4	3	2	1
				Using L2F, all packets
				are encapsulated and
D	C	B	A	forwarded to the Cisco 7206
				for reassembly of the multilink
				and single link process
				HSSI	Internet
					access

Modem		Cisco 7206 used for
		offload processing
		and has a rigged bid
		for each call
	PC

S6486

Using the Stack Group Bidding Protocol

The Stack Group Bidding Protocol (SGBP) is a critical component used in multichassis multilink sessions. The SGBP unites each Cisco AS5200 access server in a virtual stack, which enables the access servers to become virtually tied together. Each independent stack member communicates with the other members and determines which device CPU should be in charge of running the multilink session and packet reassembly—the duty of the bundle master. The goal of SGBP is to find a common place to forward the links and ensure that this destination has enough CPU to perform the segmentation and packet reassembly. (Refer to Figure 56.)

When SGBP in configured on each Cisco AS5200, each access server sends out a query to each stack group member stating, for example, “I have a call coming in from walt@options.com. What is your bid for this user?” Each access server then consults the following default bidding criteria and answers the query accordingly:

•Do I have an existing call or link for the user walt@options.com? If I do, then bid very high to get this second link in to me.

•If I do not have an existing call for walt@options.com, then bid a value that is proportional to how much CPU I have available.

•How busy am I supporting other users?

Cisco IOS Dial Services Configuration Guide: Network Services

DNC-319