AIS AI2524 user manual How AutoInstall Works, Acquire the New Routers IP Address

Chapter 5: Using AutoInstall

How AutoInstall Works

Once the requirements for using AutoInstall are met, the dynamic con- figuration of the new router occurs in this order:

1.The new router acquires its IP address. Depending on the interface connection between the two routers and/or access servers, the new router's IP address is dynamically resolved by either SLARP re- quests or BOOTP or RARP requests.

2.The new router resolves its name through network-confg, cisco- net.cfg, or DNS.

3.The new router automatically requests and downloads its configu- ration file from a TFTP server.

4.If a host name is not resolved, the new router attempts to load router-confg or ciscortr.cfg.

Acquire the New Router's IP Address

The new router (newrouter) resolves its interface's IP addresses as:

zIf newrouter is connected by an HDLC-encapsulated serial line to the existing router (existing), newrouter sends a SLARP request to existing.

zIf newrouter is connected by an Ethernet, Token Ring, or FDDI in- terface, it broadcasts BOOTP and RARP requests.

zIf newrouter is connected by a Frame Relay-encapsulated serial interface, it first attempts the HDLC automatic installation process and then attempts the BOOTP or RARP process over Ethernet, Token Ring, or FDDI. If both attempts fail, the new router at- tempts to automatically install over Frame Relay. In this case, a BOOTP request is sent over the lowest numbered serial or HSSI interface.

The existing router (existing) responds in one of these ways depending on the request type:

zIn response to a SLARP request, existing sends a SLARP reply packet to newrouter. The reply packet contains the IP address and netmask of existing. If the host portion of the IP address in the SLARP response is 1, newrouter configures its interface using the value 2 as the host portion of its IP address and vice versa. (See Figure 5-1.)

August 1997	Page 5-5
2524UM