Cisco 700 Series Platform Features

Cisco 700 Series Platform Features

Platform Cisco 761 Cisco 775 Cisco 776
ISDN interface S/T S/T S/T and U
Analog ports No Yes, RJ-11 No
Ethernet 10-BaseT Four-port 10-BaseT 10-BaseT

Cisco claims that each of the 700 series routers can support up to 30 users; however, in practice,
the limitations of ISDN and the platform realistically place fewer than 10 users as a more
reasonable population.
The 700 series also supports the following configuration features:

DHCP Relay This can forward DHCP client requests to an off-subnet DHCP server. DHCP
provides automatic IP addressing, which can greatly reduce the administration overhead of
manual addressing.

DHCP Server This feature enables the 700 series router to provide the DHCP Server function
as opposed to forwarding DHCP requests to an external server. Although this feature might
have some benefits, most large corporations prefer to use a centrally located and administered
server and leave the routing function to the routers.

Port Address Translation (PAT) PAT is an interesting feature for the designer and administrator
to consider. It can significantly conserve address space because all devices share a single IP
address to the outside network. The router alters the port number and maintains a dynamic oneto-
one relationship between the source IP address and port and the altered port assignment.
Unfortunately, PAT and its associated feature Network Address Translation (NAT) do not function
correctly with protocols that embed the IP address, including NetBIOS packets. This makes
these features difficult to implement in Windows installations that rely on NetBIOS functions.

Compression The 700 series routers can compress data by using the Stacker compression
algorithm when communicating with Cisco IOS-based routers. Compression is a method by
which computing devices substitute longer strings of repeated sequences with token or symbolicnotation; the net result is a reduction in the number of bits required to send data. There is a performance
penalty because the routers must compress and decompress the data stream; however,
this is negligible in lower bandwidth instances.

IPX and IP routing All 700 series routers support IPX and IP packet routing. Bridging is
offered for support of other protocols. This is not a major issue for many corporations because
IP is easily the dominant protocol. However, it does mean that Macintosh environments that
have not migrated to IP will likely wish to select another platform. Stated another way, Apple-
Talk is not included in the 700 series and is not on the exam.

Bonding The Cisco 700 series routers support Multilink Protocol (MP) bonding, which
allows for the aggregation of two or more channels into a single logical connection. Bonding can
be used to improve the throughput when only low-bandwidth links are available.

Management Simple Network Management Protocol (SNMP) management is available with
routers in the 700 series. This allows for pooling and trap alarm messages. Some organizations
do not opt to manage their remote equipment (home-based) due to the volume of false error
messages and the sheer number of devices.

Multinational support The 700 series routers support both North American and international
applications, including most major ISDN switches. The platform is certified for use in more than
25 countries. Administrators should check with the Cisco website or their sales representative for
a current listing of countries, and remember to verify power requirements for their installation.

Support for telephone services Specific models of the Cisco 700—including the 765, 766,
775, and 776—provide telephone services over ISDN, including call-waiting, call-hold, and
call-retrieve. The telecommunications service provider must make these services available.
Snapshot routing The Routing Information Protocol (RIP) is a fairly chatty protocol, sending
a full update every 30 seconds. Snapshot routing resolves the problems that result from using
RIP on an ISDN circuit. Because ISDN is tariffed on a per-minute basis in most installations, it
would not be cost-effective to have the circuit open all the time just for routing updates.

Snapshot routing caches the dynamic routing information and maintains it in the router’s route table
even when the link is down.