Nortel Networks WEB OS 212777 - Manual (Page 472)

Web OS 10.0 Application Guide
472 n Glossary
212777-A, February 2002
SIP (Source IP
Address) The source IP address of a frame.
SPort (Source Port) The source port (application socket: for example, HTTP-80/HTTPS-443/DNS-53).
Tracking In VRRP, a method to increase the priority of a virtual router and thus master designation
(with preemption enabled). Tracking can be very valuable in an active/active configura-
tion.
You can track the following:
n Vrs: Virtual Routers in Master Mode (increments priority by 2 for each)
n Ifs: Active IP interfaces on the Web switch (increments priority by 2 for each)
n Ports: Active ports on the same VLAN (increments priority by 2 for each)
n l4pts: Active Layer 4 Ports, client or server designation (increments priority by 2
for each
n reals: healthy real servers (increments by 2 for each healthy real server)
n hsrp: HSRP announcements heard on a client designated port (increments by 10
for each)
VIP (Virtual Server IP
Address) An IP address that the switch owns and uses to load balance particular service requests
(like HTTP) to other servers.
VIR (Virtual Interface
Router) A VRRP address that is an IP interface address shared between two or more virtual rout-
ers.
Virtual Router A shared address between two devices utilizing VRRP, as defined in RFC 2338. One vir-
tual router is associated with an IP interface. This is one of the IP interfaces that the switch
is assigned. All IP interfaces on the Alteon Web switches must be in a VLAN. If there is
more than one VLAN defined on the Web switch, then the VRRP broadcasts will only be
sent out on the VLAN of which the associated IP interface is a member.
Virtual Server Load
Balancing Classic load balancing. Requests destined for a Virtual Server IP address (VIP), which is
owned by the switch, are load balanced to a real server contained in the group associated
with the VIP. Network address translation is done back and forth, by the switch, as
requests come and go.
Frames come to the switch destined for the VIP. The switch then replaces the VIP and with
one of the real server IP addresses (RIP’s), updates the relevant checksums, and forwards
the frame to the server for which it is now destined. This process of replacing the destina-
tion IP (VIP) with one of the real server addresses is called half NAT. If the frames were
not half NAT’ed to the address of one of the RIPs, a server would receive the frame that
was destined for it’s MAC address, forcing the packet up to Layer 3. The server would
then drop the frame, since the packet would have the DIP of the VIP and not that of the
server (RIP).
VRID (Virtual Router
Identifier) In VRRP, a value between 1 and 255 that is used by each virtual router to create its MAC
address and identify its peer for which it is sharing this VRRP address. The VRRP MAC
address as defined in the RFC is 00-00-5E-00-01-{VRID}. If you have a VRRP address
that two switches are sharing, then the VRID number needs to be identical on both
switches so each virtual router on each switch knows whom to share with.